Solar Satellite Power with Laser Propulsion and Reusable Launch Vehicle
Posted by Gail the Actuary on June 14, 2009 - 11:06am
Topic: Alternative energy
Tags: space solar power [list all tags]
This is a guest post by Keith Henson.
Could Satellite Solar Power (SSP) solve worldwide energy problems and even sequester serious amounts of carbon dioxide? In this post, I look at SSP built with laser propulsion and a new Reusable Launch Vehicle (RLV) combination, since this approach seems to be lower cost than other approaches and still could produce a huge amount of electric power. If there is enough electric power, some of it might even be used to sequester carbon dioxide by converting it to synthetic oil.
In this post, I prepare a financial model (available as a spreadsheet in PDF form) of what this approach to SSP might cost. Based on my calculations, the total investment required would be $58 billion, spread over a little over eight years. The system would produce a huge amount of electricity, so that long-term, the cost per kWh would only be $ .02.
While this proposed approach may not come about, or could take 20 years, it does offer a way out, if it can be made to work. There have been two recent posts on SSP that may be of interest to readers - one by Darel Preble and another by Big Gav.
With substantial input from Jordin Kare, Spike Jones, Howard Davidson, Ron Clark and others, I have been working for the past year on a new approach to SSP’s primary problem - reducing launch cost to orbit. If power from space were abundant and low enough in cost, we could even put carbon dioxide back into empty oil fields as synthetic oil.1 The goal is to reduce the cost of transport to Geosynchronous Earth Orbit (GEO) by a factor of ~200 over current expendable rockets.
This work has been on "pop up and push," i.e., rocket boost to a few hundred km and a long ablation laser push for the rest of the delta V, (change in orbital velocity) to GEO. This takes advantage of the large thrust available from chemical rockets and the high exhaust velocity of lasers. The method allows much larger payloads than laser propulsion alone. It offers a substantial improvement over rockets. With chemical rockets, only one part in sixty of the lift off mass gets to GEO. It's 14 km/sec to GEO, (Figure 1), and 14/4.5 is about 3. As you can see from Figure 2, fuel is 20 times the rocket and payload together.
The combination of a mass ratio 3 rocket first stage (4 km/sec) and mass ratio 2 laser second stage (10 km/sec) could (according to the rocket equation) deliver one part in twelve of the lift-off mass to GEO, a significant 5 to one improvement.
The problem with that scheme is that many very expensive lasers must be in place before the first launch. I have not run a pro forma financial analysis because the rough numbers (well over $100 billion) are so daunting.
Recently another option came to my attention, the Skylon Spaceplane designed by Reaction Engines Ltd, in the UK.2 Performance, development and production cost of Skylon and SABRE (Synergic Air BReathing Engine) was obtained from Reaction Engines. By using air in place of oxygen to 26 km and Mach 5.5, then shifting SABRE to rocket mode, a Skylon is projected to place a modest (12 t) payload into LEO (Low Earth Orbit).
The April 2009 contract between PG&E and Solaren for 200 MW of space solar power generated many news stories and demonstrated the strong market for clean SSP energy - even though it has never been fully demonstrated (due to SSP’s intrinsically large scale).
A pro forma financial model was created using cost information provided by Reaction Engines, prior knowledge of laser propulsion, informal cost estimates for high kg/kW SSP and propulsion lasers and the 2016 delivery time for the PG&E/Solaren contract.
Pro Forma Model Assumptions (PDF spreadsheet here)
The model uses Reaction Engine's published development numbers. We doubled this to $21.7 B and compressed the development time in half to five years starting in 2010. First vehicle flies in 2015. Production Skylons in the pro forma model decline from $450 M to $292 M after 10,000 flights and vehicle life increases from 200 flights to 500.
Laser and GEO focusing mirror development is assumed to require $2 billion.
The proposed power satellite design is a very conservative 5 kg/kW or 5,000 tonnes per GW. (The project would still make money at 10,000 t per GW.) Development cost of $4 B seems reasonable by taking a low-tech approach and not being too concerned with mass. Four billion dollars should be enough money to rough design three (one PV and two solar dynamic cycles). A substantial fraction of this money will be for design of construction facilities at GEO. Other than being able to be broken down into loads that fit the transportation system, mass is even less of a factor for the "dockyard."
Working capital is also not included in the model because the time between purchasing parts for a power satellite and selling the new power satellite is under 90 days. The construction facility at GEO to build 1 GW power satellites is assumed in the model to be equal to the first power satellite mass (5000 tonnes). One GW is not optimal for power sats. As the increasing flow of materials makes larger-size power satellites practical, the model enlarges the construction facilities by 5000 tonnes per GW.
There is no provision in the financial model for robot assembly or teleoperators. The model assumes up to 1000 workers at GEO. Food and oxygen supply for the workers is not included because it is no more than 1 part in 240 (ten tons per day out of 2400). Wages for the workers in space is not included either because wages (at $500,000 per worker per year) would be one part in 365. (A GW turned out every two days and the net profit after transport cost and parts is a billion dollars per GW.)
Flights to orbit (sub-orbital as more lasers come on line) increase by three additional flights per day per quarter. I assumed the lasers to take over providing delta V in a linear way. As the lasers grow from a few MW to eight GW, payload per flight grows from six tonnes to twenty-five.3
Skylon's ability to go to LEO means that a single 6 MW laser built for $60 million (after development) can raise six tonnes of power sat parts from LEO to GEO in a day. This is a huge improvement over building $40 B of lasers.
Figure 4. This graph shows the trajectory resulting from a 290 tonne Skylon booster vehicle, carrying a 40 tonne laser stage sub-orbital. The stage is then boosted to GEO by 4 GW of ground based lasers. Payload to GEO is 14.5 tonnes. Laser stage mass rises to 50 t and payload to GEO to 25 t with 8 GW of laser. The vertical axis is nautical miles altitude; horizontal axis is downrange. The constant laser acceleration applied is 1.1 g , much less than the rocket burnout of 3.5 g.
We still build the lasers, but in this model, we buy the lasers over a long time with power-satellite sales. Each laser requires a focusing mirror in GEO. Only one mirror has to go to GEO the hard way (with rockets). We bootstrap the rest up at 50 mirrors a quarter with laser power from the first.
The model has been adjusted so that by the end of 2016, there is ~10,000 tonnes at GEO, enough for the construction facility and parts for the first 1 GW power sat. A linear ramp from zero over 18 months would put the first flight in mid-2015. The flight rate over the next year ramps up to 12 per day. The fleet size assumes flying 1.5 times a day.
Production of Skylons (counting the prototype) by the end of 2016 is 14 with a peak rate of five per quarter. Skylons are similar in size to 747s. Boeing built 747s at higher rates.
The focusing mirrors for the lasers reduce net cargo to GEO by 250 tonnes per quarter. We assume the lasers and focusing mirrors will cost $10/watt. Depending on how much laser power will fit into a standard shipping module, the project installs 50-250 laser modules per quarter.
This involves purchase or construction of 200-1000 "on the ground" laser modules per year. Scaling the factory size from locomotives, the plant making the lasers might be a square mile. The cost of this factory has not been included. In this model, we ramp up and install lasers at a GW per year for 8 years. The factory should reach excellent economy of scale with a production run this long. Financing for the factory could be based on a firm order of this size.
The model accounts for power satellites not sold but diverted internally to make Skylon propellants and to power the lasers. (The cost of the propellant plant and the laser infrastructure such as a refrigeration plant to cool the lasers has not been included.) By the beginning of 2018, the lasers and propellant plants in the model are using ten GW of the 84 GW produced by that date (split almost evenly between lasers and propellant).
Figure 5. A mature laser boost system as envisioned by Dr. Stuart Eves, Surrey Satellite Technology. The laser stage makes 1 1/2 orbits so the mirrors will be in the correct place to circularize the orbit at GEO.
The initial design capacity of the system builds up over 8 years. At that point of maturity, it is launching 50-ton laser stages and using 8 GW of lasers (1600 modules). There are 4 sub-orbital Skylon flights an hour, less than 100 flights per day. They lift about 800 million kg per year on sub-orbital flights. Not taking the Skylons into LEO might extend their life (though it may complicate recovery). The price per kg lifted to GEO falls from an initial $750/kg (based on twice the depreciation of the Skylons and mass ratio 2 laser stages) to $50/kg. This reduction is due to the cost per flight (lower cost, higher life) and the payload at GEO rising from six t per flight to 25 t per flight due to more lasers.
For a simple financial model, we have conservatively figured net profit for power satellites (not counting transportation otherwise covered) at $1 per watt. If power satellite parts cost $600/kw, then a 1 GW power satellite would sell for $1.6 B. This is 2 cents per kWh based on a ten-year recovery of capital. (It does not include the customer’s associated rectenna.) The market for power in the 1-2 cents per kWh range is close to unlimited because of the demand for low cost synthetic oil.
The model is full of feedback loops because of the bootstrapping. When it first starts, one laser/mirror lifts the cargo of one Skylon flown once a day. That is 12 tons per to LEO and six tons per day to GEO. Two lasers/mirrors allow the Skylon to fly twice a day for 12 tons per day to GEO. More Skylon and lasers rapidly build up the cargo capacity (the effects multiply). (Missing, the cost to boost the first mirror to GEO. IOSTAR's tug may be how we maneuver it into place.)
Figure 6. In this draft model the red line tracks cumulative profit / loss (in millions of dollars) each year and the black line shows annual sales - $1.5 - $2 Billion/Gigawatt. The debt bottoms out in 8.25 years at just over $58 billion dollars. That is about twice what the Chinese spent on Three Gorges Dam. For that they obtained 22 GW at a human cost of displacing 1.24 million people. Mature, this project would provide 22 GW of new generating capacity every 44 days.
At the peak investment, power satellite sales in the model are over $4B/year. Refining the model will cause this peak investment and timing to grow or shrink due to conceptual improvements, the minor items mentioned above, those cost items not yet considered and a more realistic (higher) initial sales price for power satellites.4
The current model shows repayment of the entire investment from selling power satellites only nine quarters after reaching the bottom at 8.25 years. (Interest on the capital investment has been included.) The delivery of power satellite parts and power satellite sales grows rapidly after that point.
Current world energy demand is around 15 TW. The "Manhattan Project" crash program outlined here has ~30 TW on line by 2043. World usage of fossil fuels beyond 2040 should be negligible. (Lower cost carbon neutral synthetic fuels would displace liquid fossil fuels.)
The model shows producing over four TW/year of new power satellites by 2040. Four years of power satellite production at this rate would be over 15 TW, enough to put 100 ppm of CO2 back in the ground as synthetic oil in two decades following 2040.
The proposed power satellite financial model makes considerable profit in addition to solving carbon dioxide and energy problems. How to finance it and who might finance this approach to solving the carbon dioxide and energy problems as well as potential military uses of the propulsion lasers are outside the scope of this analysis.
Notes
1 The area of the earth is ~5.1 x 1014 square meters; air pressure is ~100,000 N/m2. The force would be ~5.1 x 1019 and the mass (force/acceleration of 9.8 m/sec2) is ~5.2 x 1018kg or 5.2 x 1015 t. One ppm would be 5.2 x 109 t and 100 ppm would be ~520 billion tonnes.
It takes ~100kWh to remove a ton of CO2 from the atmosphere.
http://www.eurekalert.org/pub_releases/2008-09/uoc-cd092908.php
Removing 100 ppm of CO2 from the air would take 52000 billion kWh or 52,000 TWh, or since a year is about 8700 hours, about six TW years. A TW is about twice the installed power in the US.
It would take a 1000 1GW nuclear reactors 6 years to bring the CO2 level back to the level of 1960 if no new CO2 was being added.
The problem is what to do with the CO2? Liquid CO2 has a density of 1.1. As liquid, this much CO2 would occupy ~470 cubic km. It would cause a real problem downwind if it blew out of storage. We know that oil stayed in the ground for millions of years.
It takes ~50 times as much energy to convert CO2 to synthetic oil as it does to capture it. So to convert 100 ppm of CO2 to synthetic oil would take ~300 TW-years. If we are already feeding 15 TW into making synthetic oil, we could dedicate another 15 TW into making more and pumping it back into empty oil fields. It would take two decades at this rate to bring the current CO2 level back to that of 1960. We might be able to take the CO2 level down far enough to get the earth to go into an ice age (for those who like to ski).
For the details on the energy cost of making synthetic oil see www.htyp.org/dtc
2 http://en.wikipedia.org/wiki/Reaction_Engines_Skylon
3It is our economic judgment that lasers become useful when there is enough power to raise a 12-ton stage with mass ratio of two to GEO in a day. LEO to GEO is 4.1 km/sec. For a mass ratio of two, the exhaust velocity is 4,1/.69 which is ~six km/sec (ISP of only 600!). We assume multi impulse Hohmann transfer rather than spiral. Twenty-four hours is 86,000 sec.
V=at, a=v/t a 4100/86000 =~0.05 m/sec2. One m/sec2 is ~0.1 g so this is half a percent of a g.
How much mass must be blown off in one second to get 0.05 m/sec2
MV = mv where M is the current laser stage mass, V is 0.05 m/sec and m is the mass blown off in one second at velocity v, 6000 m/sec.
m/sec = 0.05M/v = 0.05m/sec2 x 12,000kg/6000m/sec
m/sec is 0.1k/sec
Ke (of exhaust) =1/2mv2
Ke = 1/2 (0.1) (6000)2 =1.8 x MJ
Laser efficiency of 30% increases this to six MJ.
Since this is over a second, the laser power to provide six MJ/sec is six MW.
The payload multiplier as a function of laser power is from this number and other work indicating delivery of 25 t of payload from a 50 t laser stage placed in a 300 km sub orbital flight.
4There may be resistance to paying a great deal more than the projected cost in a few years.
Thanks for these ideas!
It seems like if your ideas were feasible for three times the cost, in a much longer time period (say 20 years instead of 8 to maximum investment), they still would be phenomenal. While the ideas may seem way out, it seems like we need to examine all our options closely.
Gail,
Since you posted this piece, please identify Keith Henson, his background and his affiliations. Isn't it bad form to leave that out of the opening window? Aren't you being a bit too one sided with this (again, I might add)...
E. Swanson
Contrasted with node 5447 I'm certainly puzzled.
"Since you posted this piece, please identify Keith Henson, his background and his affiliations."
http://en.wikipedia.org/wiki/Keith_Henson
Of course lots of people seem to *want* low energy world, including a population die back to one or two billion people. Ran into this the first time clear back in 1975 at a Limits to Growth conference. The just formed L5 Society was promoting power satellite. I as a junior member of the team that included Dr. Peter Vajk. He was talking about how power satellites built from lunar resources could really change their disaster models. We were nearly thrown out.
Keith, I just posted a rather polite comment, then refreshed my browser, saw this, and realized what deep denial you're in.
"realized what deep denial you're in."
Hmm. Can you explain what you mean? It is just an observation as far back as 1975 and as recent as last year when Dr. Robert L. Hirsch like to burned my ear off when I suggested there could be a technical breakthrough that could replace fossil fuels.
Sigh. I probably shouldn't have posted that, I know you mean well.
And now you've asked me to clarify it, which is even more awkward.
I mean it in the same sense as I would apply it to the Jehovah's Witnesses who come to my door. They have a paradigm they want to share, and it's a humdinger in terms of features and payoff, and they mean well. Their worldview just has a very low probability of being correct under reasonable standards of analysis. So I thank them and wish them well, which is what I should have done here.
I mean that people like myself who have concluded that a human dieback is probably inevitable don't WANT a dieback, for the most part they have come to unpleasant conclusions after serious study. Your comment about "wanting dieoff" struck me in the same vein as a Jehovah's witness concluding you must want to go to hell if you don't join them saving souls, and I reacted. (At the link you posted, I see you've also been a proponent of cryonics. I wish you luck with the frozen head thing.)
You should give Hirsch more respect. It isn't necessarily due to a bad attitude (as in a desire for billions of deaths) when someone disagrees with you.
"Your comment about "wanting dieoff" struck me in the same vein as a Jehovah's witness concluding you must want to go to hell if you don't join them saving souls, and I reacted."
Perhaps it is incorrect of me to assume they are in favor of a die off when they reject that there even could be a solution to the carbon/energy problems. Operationally though it's the same thing.
Hirsch, like yourself, has worked through the consequences of the data and concluded that a major die off is inevitable. He is hostile to any possibility that his world view might have a flaw in it. This strikes me as religious-like dogmatic thinking.
I can't fault him though, it's probably a more comforting world view than mine. Like Ray Kurzweil and Vernor Vinge I see the technological singularity as inevitable. Only instead of it being the rapture of the nerds, I see our brains being eaten by friendly AIs.
Still, to enjoy this, we probably have to solve energy problems first.
Far out. On what basis do you predicate a Singularity as inevitable? And why would we need to muck about in LEO if we're due to be uploaded soon?
Forgive me for being skeptical. We have a historical record chock full of collapsed civilizations owing to overshoot, after all; also decades of predictions of inevitable breakthroughs in all manner of tech including Kurzweil's nano-based solar. Prudence is warranted when making decisions as to what directions mankind should head in to secure energy supplies sufficient for people to lead a comfortable lifestyle; should we spend $60 billion on SPS or a program for switching the OECD shipping fleet over to alternate fuels we can secure domestically?
As others have commented at present funding options are limited, and many believe the crude oil price runup/spike was a major factor in the present recession. If they are correct, bets are that, in the short term at the least, money will be thrown at solutions that are literally more mundane than SPS.
Where is Hirsch saying that he foresees dieoff? All I've ever heard him predict is that peak oil will lead to extreme hardship, economically and socially. This doesn't equate with mass starvation at all.
"On what basis do you predicate a Singularity as inevitable?"
I don't see any way to avoid it. Singularity is AI and molecular nanotechnology. If we got AI one of the first things to do with it would be to develop nanotechnology. If we got nanotech, one of the things we could do is brute force AI by scanning brains. I knew Eric Drexler from the mid 70s on, been thinking about this for 30 years.
But an energy induced fall in the population looks like it will start decades sooner than mid 2040s--which is where Kurzweil (who has studied it more than anyone) thinks it will happen.
"And why would we need to muck about in LEO if we're due to be uploaded soon?"
It's GEO that's interesting, not LEO. And if I could be certain the singularity would happen before mass starvation and wars start taking the population down I wouldn't bother to think about energy.
The only page I know about that touches on both issues is here: http://www.drmillslmu.com/peakoil.htm
"Which will arrive first? Ecological overshoot and collapse (Malthus), or
a "techno-fix" (Kurzweil)?
No one knows.
But, we probably won't have to wait long to find out. One of these two scenarios will likely
occur within the next several decades. But, which one?
Generally it is healthy to be optimistic.
But optimism can be deadly if it produces a Pollyannaish denial of real problems.
We should not ignore problems by assuming "someone else" will take care
of it, or that "the market" or "technological breakthroughs" will always come
to the rescue in time.
Solutions may not come in time, and we may get a quite rude Malthusian
smack down later. (In my opinion, should the internet go down due to
energy shortages, the Mathusian writing will be on the wall... )
To avoid this, we must solve the transition from our finite, depleting oil resources
to renewable energy.
Technological civilization runs on energy.
****************(end of quote)
". . . should we spend $60 billion on SPS or a program for switching the OECD shipping fleet over to alternate fuels we can secure domestically?"
This *is* a program for alternate fuels. Power at a penny a kWh (what else can you do with off peak power?) can be used to make hydrogen. Hydrogen and C02 reacts just fine to make synthetic oil. True, you only get 56% of the energy in the liquid fuels, but at a dollar a gallon who cares?
Going for SBSP is unlikely to be our decision. (as in the US)
I see no evidence the US could go back to the moon, much less cope with something of this scale.
"extreme hardship, economically and socially"
Is a euphemism for mass death due to wars, famines, epidemics due to weakened immune systems and freezing in the dark. Consider figure 14 here: http://www.theoildrum.com/node/3091 I am sure Hirsch is familiar with it. Hirsch may not be willing to consider a ray of energy hope (for emotional reasons tied to his commitment to this grim future) but he is nobody's fool. When he talks about coming out on the far side in better shape, he is talking about a world with far fewer people.
In some ways that might be a better world. It also might be rather radioactive. In any case, it's going to be a bad time I had rather avoid if possible.
From a strategic point of view this would appear to be an easy system to knock out. In a war situation a belligerant could launch debris or individual satellite killing devices. Anyone dependent on such power sources would immediately be in the dark. In an instant all of that investment could be wiped out. Any proposed energy system should have source diversity (lack of a single kill switch) as one of its requirements.
"From a strategic point of view this would appear to be an easy system to knock out. In a war situation a belligerant could launch debris or individual satellite killing devices."
I am a bit curious as to why someone with the capacity to do it would do it. In a very short time I expect every advanced country would have hundreds of power sats.
One point of this project is to reduce resource competition and therefor the basic reason for wars.
Energy is not the only cause of war or scarce resource in the world. What about ideology - the cause of most wars?
The threat of war will never be eliminated. The only way the threat can be reduced is to have diversity in power sources. If a single madman can wipe out the world then it would have been done many times already. The reason it has not occurred is that we have had diverse ideologies and power sources. Making people dependent on a single kill switch solution (such as your satellites) renders everyone easily vulnerable to such a madman scenario.
"Energy is not the only cause of war or scarce resource in the world. What about ideology (cause of most wars)"
I make the case in "Evolutionary Psychology, Memes and the Origin of War" that ideology is the result of anticipated resource shortages rather than a cause.
"and access to metals?"
With loads of energy you can make metals out of country rock.
North Korea (if it wished) has the same access to scarce resources (including energy) as South Korea. Ideology is the only difference between North and South. Extremist ideology has minimal relationship to energy resources. North Korea could easily wipe out your suggested satellite system many times over with their existing technology.
Assuming they could (a stretch) and they wiped out a Chinese power sat, how long do you think they would last?
The Chinese would be in cahoots and would have the North Koreans knock out US and European satellites on their behalf. Proxy wars are old.
I suppose that's possible. Remind me to have my power sat insured by a Chinese company.
If you want diversity of power sources, which I agree with, then introducing SSP is certainly a good thing. SSP certainly has no single "kill switch". For starters the rectenna on the ground is owned and defended by the local utility and nation receiving the power. The satellite in space would be defended even better by various national military, even better than the growing fleet of communications and other satellites. The increased defense of national and global interests in near space is necessary as our global economic infrastructure increases its presence in cis-lunar space. We must reduce our environmental footprint on earth. I don't think you understand how difficult it would be to "kill" an SSP. It would be sort of like attempting to destroy the interstate highway system with a bomb placed anywhere you like. We may have difficulty preventing that bomb, but violators will be swiftly located and introduced to corrective measures. Everyone that has reliable electric power wants to see their electric power continue.
What about ideology - the cause of most wars?
Are you sure that Ideology is not being used to 'sell' the war VS being the cause?
Back in 1908 - 1912, the dominant meme in the west was that the Great Powers were too interdependent (financially and in trade) for a major war to be possible. There was no "reason for war."
Every technology since steam has been promoted as "reducing the reason for war." Notably, nuclear fission proponents pushed this long and hard. Strangely, despite all these wonderful technologies (that we already have), we still seem to need to "reduce the reason for war."
War does not need reasons.
Two questions:
The problem I have with your argument is the same one I have with Kurzweil's, namely that having the physical capabilities to do something (simulate brains, scan brains) doesn't imply the knowledge or skills needed to exploit that (create strong AI). A scanned brain is just a big pile of data; using that data to create a super-human intelligence is by no means a trivial feat.
This appears to be why Kurzweil's predictions for AI were so off the mark - he's fixating on hardware and ignoring knowledge, which based on my experience is the harder part of solving most problems. (FWIW, his first book is online at his website, and it's interesting to look at his predictions for AI and compare them to what actually happened. With one exception - chess - he was uniformly and wildly over-optimistic.)
Do you have a link to a detailed analysis showing 56% efficiency for electricity-to-oil? I've been trying to find empirical evidence for the efficiency of synthetic oil, but there doesn't seem to be data for an actual implementation of the hydrogen-to-oil leg. There is such data for electrolysis, but all industrial-scale installations I've seen data for were under 50% efficiency.
"Why would nanotech necessarily allow brute-force scanning of brains? "
Molecular disassemblers, an obvious product.
"Why would being able to scan brains necessarily lead to AI? "
Simulation.
Finely infiltrating a brain with enough sensors to tell what the cells were doing would probably work as well.
"Do you have a link to a detailed analysis showing 56% efficiency for electricity-to-oil?"
I worked out the mass and power budget for a 1000 bbl/day forward fuel synthesis plant for the military. It ran on ~100 MW input. I worked the efficiency just before a talk and seem to have got it wrong. I can't get as that low an efficiency now. A bbl of oil is about 1.7MWh. 1000 bbls would be 1700 MWh. 24 hrs x 100 MW is 2400 MWh. 17/24 is 71%. 98% of the energy is for making hydrogen. That could range up to 120 MW which would lower the efficiency to 59%. Some of this could be recovered making steam while cooling the Fischer-Tropsch reactors.
How would that help?
We have no lack of human-level intelligences already - they're called "humans". Why would simulating a few more let us do something new? If the already-existing human intelligences couldn't come up with a supra-human intelligence, why do you so blithely assume the addition of simulated human intelligences would change that?
This isn't a board full of people already convinced of the inevitability of a technological singularity; you can't just wave your hands and say "magic happens" and expect people to believe you.
You're making an enormous assumption about what nanotech can and cannot do. Your argument seems to boil down to:
That's not a persuasive argument. It's more like a statement of faith.
Where is your evidence that a 1000 bbl/day plant runs on 100MW? You can't just arbitrarily choose both input and output volumes, otherwise you've chosen the conversion efficiency, which is exactly what you're trying to calculate!
If this is an example of your calculations, no wonder they don't make sense - you're just making shit up.
Garbage in, garbage out - if there's no evidence behind the numbers you put into your calculations, there's no point in doing the calculations. Industrial electrolysis is 50-70% efficient, meaning that if you seriously believe creation of synthetic diesel from electricity is going to be 70% efficient, you very clearly have no idea what you're talking about.
This is simply embarrassing; are you trying to make renewable energy people look unrealistic and out of touch? That is what you're doing, and right now that's more harm than help.
"Where is your evidence that a 1000 bbl/day plant runs on 100MW?"
Basic chemistry
Liquid fuels can be made out of carbon dioxide by n(CO2) + n(3H2) --> (CH2)n + 2n H2O. (It's exothermic.)
120t C, 60t H2 makes 140t synthetic oil, which is about 1000 bbls
Recipe for 140t of synthetic oil per day
Carbon 120t (5t /hr)
Hydrogen 60t (2.5t/hr)
(40t of Hydrogen combines with the oxygen and is recycled.)
It takes about 100kWh/t to remove carbon dioxide from the air. See http://www.eurekalert.org/pub_releases/2008-09/uoc-cd092908.php (This is equal to 360 kWh/t of carbon.)
Experimentally these researchers have removed CO2 from air at a rate of 20 tons per year with a square meter of scrubber
20 t/year/square meter
20t/year/365/year/m2 x 12/44 = 0.0149 t/d/m2 (C)
120t/d/0.0149 t/d/m2
= 8000m2
100kWh/ton of CO2
366kWh/t of carbon.
5t/hr / .36 MWh/t = 1.8MW
Sanity check , 120t of carbon per day is 5 t/hr Air is 350 ppm CO2 or 95 ppm carbon
1,000,000t of air has 95t of carbon in it
Tonne of air has a volume of about 800 m3
About 1.2 billion m3 of air per day.
Or 1.2Bm3/8000m2, 150 km/day or about 6 km/h. (Half the average wind speed and not as big as the rectenna.)
Electrolytic hydrogen requires 48 MWh/t currently. Recent results from MIT make it possible the energy might get down to 33MWh/t. The chemical equation above requires sixty t of H2 to 120t of carbon.
2.5t/h x 48MWh/ton = 120MW (Theory is 33MWh/t, 83 MW)
For rough numbers, ignore the small energy cost of carbon and use the average of the above line.
"Molecular disassemblers, an obvious product."
Tea. Earl Gray. Hot.
Sorry, Keith. I like graph paper a lot, too. But your overconfidence in the predictive abilities of calculation are like expecting a man who is the same weight and height of Shakespeare to arrive at the same products as long as you give him enough paper..
.. I'm going to my shop, where I can spill some more coffee on that graph paper that earnestly tries to tell me how to connect Post A to Gimbal B ..
Bob
Thanks Pitt. Once again you've said it for me.
The fact that somebody has been thinking about it for decades does not mean didley squat. Brilliant mathematicians spent centuries thinking about how to eliminate Euclid's postulate about parallel lines because their intuition told them that it was not necessary. Guess what? They were all wrong.
Hi Greenish,
Does he mean well? Or is he just caught up in his own technological delusion?
What a depressing post - like the Hydraulic Fracturing essay the other day. I really don't fault Gail for bringing up these technologies - this is our reality - she is more than justifed in bringing them to light. Just as in the other post, I'm sure that Rockman is extremely knowledgeable. And, I'm sure this fellow knows his stuff.
The problem is one of perspective. This post and the one on fracturing seem to imply that human population growth is a given and the only problem is how to accomodate that fact. The really simple solution to all of our problems is to get back into balance with the ecosphere. Basic math tells us that simple family planning measures could accomplish that by the end of the century. This obvious solution here is not to expend enormous amounts of natural resources to put gadgets in orbit, but to design better condums and birth control stuff.
To survive to the end of the century, we don't need to gamble on laser propulsion, we need to convince huge masses of people that bicycles are way more cool than cars.
I could go on - as I'm sure you could - but, is there really much hope when laser propulsion and fracturing is a lot more sexy than bikes and thinner condums.
Hi BikeDave.
I have utterly no doubt he means well; most religious proselytizers do within their self-referential worldview. And I don't begrudge any of them their visions of paradise. One person's rapture is another person's laser ablation, space fleet, frozen head, and robotic upload.
That said, it does seem to evince a rather grotesque perspective on systems thinkers. A quote from the keyposter directly above says:
So Hirsch is the one being religious, and - ipso facto - his conclusions about an inevitable dieoff must be "comforting" to him, which explains why he's "hostile" to those who realize the technological singularity (another non-falsifiable afterlife claim) is inevitable.
By any reasonable criteria, this was a religion key post. "Not that there's anything wrong with it," as Seinfeld would say.
Thanks Dave but I actually just know folks who know a lot about fracing. But I agree with your point to a degree. Fracing gas shales isn't a solution to anything....it's just a way to get more NG out Of the ground. The only potential long term benefit is if we use NG as a buffer while we move onto real solutions. IMO we don't need new tech to save us. We have all the tech now to ease the problem significantly and allow us a more peaceful transition to a low use FF world.
But we won't IMO. And I see the single biggest obstacle is the focus on short term issues. Society is dominated by the 24 hour news cycle. Folks won't tolerate a discussion today about making choices that will affect us 10 or 15 years down the road. They want solutions to finding a job, paying the mortgage, filling up the car with gasoline, etc, etc, NEXT month. The solutions to our future are in the hands of the politicians...not the scientists, not the engineers, not the geologists, not the environmentalists. and certainly not the folks who participate at TOD. And the politicians are ruled by the average citizen. I know it’s old and worn out but it still fits well: “We have met the enemy and he is US.”
Rockman wrote:
While I agree that we are our own worst enemy in many ways, I think that you miss the main point about politics as it's practiced today in the U.S. To get elected requires a massive amount of money. Much of that money comes from corporate sources and the politicians tend to satisfy the needs of those who pay their bills. To be sure, the political game involves attempting to satisfy as many voters as possible while alienating the fewest. But, there's so much corporate propaganda out there that the voters are easily influenced to demand actions which are favorable to the corporations. Besides, without a job, most of us are screwed. Still, for the politicians, the game is about power and they would not do what the corporate bosses wanted if the voters really wanted a different path.
Having worked on several presidential campaigns, I've seen how they are run from the inside. I even tried to get a (future) President interested in solar power back when, only to run into a wall put up by the nuclear power guys. That wall crumbled after TMI, but now it's being rebuilt, IMHO...
E. Swanson
I am in complete agreement with you as far as attacking the overpop problem from the side of managing reduction (through family planning, of course and not forced attrition) and not assuming a growing head count. If for no other reason than to buy time for the more exotic and ego satisfying solutions to come to fruition, if at all.........
Now, as far as how to get people to be more conservative etc. All organisisms will always take "the path of least resistance". This observation is axiomatic and immutable so we must assume it will always hold in any new arrangements.
Our current spacial order is designed around a mode of transportation that allowed for a much more sprawled geography than transportation based on human power alone can provide. Don't expect anyone to be "talked into" using a bike to travel 5 miles to procure a gallon of milk when they can just hop into the family truckster and be back in a flash without even breaking a sweat.
No, this is about the patterns that people will establish based on the environment they live in and that environment is too spread out to do much more than improve the efficiency of the current transportation modes.
There is a lot of room to trim the fat for sure but I just don't see a replacing of fuel powered transportation until a more compact geography makes it feasible.
So I guess we need to plan our cities and towns differently or more like the good old days.
In the mean time keep working on those better condoms!
I really think you're ignoring the fact that very rarely, if ever, do humans voluntarily limit their birth rate.
And I pose the question, if we have the energy and resources to grow in balance, why not? Why degenerate into an eventually doomed race limiting itself to one planet, if we can build cities in Langrange points, moon bases, terraform Mars, Niven rings, and eventually Dyson Spheres.
Sure there will be mistakes, but to do it long term, we will have to learn and incorporate deeper knowledge of ecological systems, and perhaps adapt somewhat to meet the large goals. But the future is NOT entirely calculated out, as Malthus proved, and no models have incorporated all the (currently unknownw) new ideas and new technologies into their calculations.
Might as well give up using fire.
Huh? What are you talking about? What do mean, "deep denial?" Mr. Henson's achievements and accomplishments are applauded around the world, and what have you done to improve the human condition?
|Don't complain about your intellectual and moral superiors just because you're jealous or have some other emotional or ideological issues. Mr. Henson's insites are considered by science and technology advocates around the world as roughly equal to the likes of A. C. Clarke and Azimov, so you'll have to explain what your difficulty is with Mr. Henson's achievments.
Would only be fair. }:-}
As it stands, let's hope thyat such technologies become a reality, a means of restoring some ecological infrastructure while retaining the world's admittedly shakey quality of life.
Thanks for posting this link to your background. Looking thru it, I'm certainly impressed by your experience, however, what you write does not prove the feasibility of the SBSP as you have described them. BTW, my first job after college involved working with analog computers on some satellite attitude control problems...
E. Swanson
"what you write does not prove the feasibility of the SBSP as you have described them."
I hardly described them at all. SBSP is an obvious winner *if* you can get the cost to GEO down low enough. That's what I have been trying to do. In retrospect, it involves matching the exhaust velocity to the mission velocity to get the mass ratio down. I.e., two stage to GEO with most of the delta V in the second stage using 10,000 m/sec exhaust velocity.
"involved working with analog computers on some satellite attitude control problems"
Cool! My first patent (long expired) was the log-antilog four quadrant multiplier. I have recently proposed using tethers for attitude control of power satellites. That's probably too technical to discuss here, but ask (hkhenson@rogers.com) and I will send you what I have. It needs more thinking, especially what happens when a fast moving rock cuts a bridal line on the transmitter disk and how to keep the whole thing from turning over around the axis of the tether.
SBSP is an obvious winner *if* you can get the cost to GEO down low enough.
Magically free? Come now - the last times the Space Power has come up I've pointed out how present land based PV cells are almost as good at getting the energy of photons to elecromotive force as the photons in space -> downshifted to Earth -> converted to electomotive force.
And on earth - repairs can get made.
Another claims 1/6 the energy of PV
http://www.vnunet.com/business-green/analysis/2202907/space-solar-power-...
http://www.theoildrum.com/node/5306#comment-494573
I asked for someone to offer up a refudiation of the 1/6 to 2x power claims. Perhaps you can?
It depends on a lot of other factors.
Roughly speaking, a system in GEO is about 4-5x more power per GWp than that system on earth (3x longer exposure + 1.5x higher energy density). Transmission efficiency is a huge unknown, but let's optimistically estimate 67%, for a total "orbital improvement factor" of 3x: the same system will generate 3x as much power in orbit as on earth, so an earth-based system that generated as much power would cost 3x as much.
If a 1kW satellite costs $600, then, a 1kW ground-based system would cost at most $1800, and probably a significant amount less (as it would likely have simpler requirements than a satellite). So the question becomes what the launch, construction, maintenance, and rectenna costs are; if they're anywhere near $1200/kW, the ground-based system is cheaper.
You're assuming 5kg/kW, or 1/200 tons; with 12 tons per flight and 200 flights per $450m ship, that's $450M / 200 flights = $2.25M/flight / 12 tons = $188,000 per ton / 200 = $938 per 5kg kW in ship costs without even considering fuel, operations, or maintenance. Your cost is already up to 85% of a ground-based system without considering more than two aspects of the space-based installation!
***
Basically, the key to your system is assuming super-cheap solar power; $600/kW from space is ~$1,800/kW on the ground, which is roughly the cost of a coal-fired system but without fuel or maintenance. That's about $600/kWp, which is roughly 5-10x cheaper than current solar power systems. Given your assumptions, the launch system is irrelevant - you could just take exactly the same technology and make a ground-based system that did the same thing but cost less.
"You're assuming 5kg/kW, or 1/200 tons; with 12 tons per flight and 200 flights per $450m ship, that's $450M / 200 flights = $2.25M/flight / 12 tons = $188,000 per ton / 200 = $938 per 5kg kW in ship costs without even considering fuel, operations, or maintenance. Your cost is already up to 85% of a ground-based system without considering more than two aspects of the space-based installation!"
You missed the main point. The first kg up cost ~$750/kg. But the cost of the Skylons comes down by 2/3rd, the life goes up reducing the cost by 2/5th and the amount go GEO goes up from 6 tons to 25 as more lasers take over more of the delta V.
The net effect is 1/15, which lowers the cost to $50/kg.
Power sat energy is fed into making fuel, so the only cost is the capital equipment.
I thought the point of the exercise was to find a way for renewable energy to cost-effectively replace fossil fuels? Given that, why insist on a demonstrably-more-expensive approach?
Given your assumptions, a ground-based system is cheaper; why insist on the space-based one, with all its unknowns and critical assumptions, unless your intent is "cool stuff in space" rather than "affordable renewable energy"?
The basic fact that you have to contend with is that you're proposing something enormously more complex than a ground-based installation, yet you're making the assumption that solar generation is extremely cheap. That means you have a fairly narrow range from which to pay for this additional complexity before simply installing solar generators on the ground is cheaper, and once all the costs you're ignoring are taken into account, your proposal does not appear to be in that range.
That's an enormous chain of advances that have to go according to plan in order for your system to work. What if there are cost over-runs on building the spacecraft? What if costs don't fall as much as you hope? What if lifetime extension requires extensive maintenance? What if these things actually cost money to maintain and operate?
Moreover, you're ignoring an enormous number of details - practically all of them, in fact. Enough that it's not really possible to evaluate your proposal, unfortunately. How can we take seriously a proposal that has spacecraft flying twice daily but doesn't allocate a penny towards operating or maintaining those spacecraft? Or towards acquiring/creating fuel? Or towards ground station costs?
Of course your proposal looks cheap - you're ignoring almost all of the costs!
Then why is there no capital cost entry for fuel synthesis plants? High-temperature electrolysis and LOH/LOX storage aren't free.
Moreover, ignoring operations and maintenance expenses for fuel synthesis, not to mention spacecraft that fly twice a day, seems...unrealistically optimistic. Suggesting that the only costs in existence are fuel and capital doesn't engender confidence in the thoroughness of the analysis.
There are too many details and too many numbers missing from your analysis. All we can conclude from it is (a) you're making a huge number of assumptions, and (b) ground-based installations would probably be cheaper and certainly have vastly lower startup costs.
The launch system Keith describes is well beyond what could be proposed and built in an SSP business case today. Skylon's SABRE engine and push-pull lasers are over the edge of feasibility. Lasers, for example, are blocked by clouds. Another major reason is that no mass market exists to support the existence of such launch to orbit vehicles. That is why Keith's budget numbers are somewhat incoherent. As another student of SSP (I contend there are no SSP experts,.. yet), I would disagree with Keith's massive use of astronauts to bolt these together - telerobotics are a thousand times more cost effective for any task stream - since they can be operated from the ground.
In my humble opinion we desperately need to have Congress charter an SSP company - just as they chartered Comsat - and see what the companies propose. There would likely be a dozen serious bidders and none of the bids need be accepted, and we would certainly learn a great deal about what in fact could be done.
"Lasers, for example, are blocked by clouds."
Beyond the first few years you don't have to have the lasers on the ground. Putting them in GEO complicates the military problem though.
"Another major reason is that no mass market exists to support the existence of such launch to orbit vehicles."
Well, duh. This *is* the mass market.
"budget numbers are somewhat incoherent"
The Skylon/laser combination came together May 17, which is less than a month ago. If anyone wants to work on the spread sheet, just ask for a copy.
"disagree with Keith's massive use of astronauts"
They wouldn't be astronauts. Iron workers maybe or whatever the Chinese term is. I am not opposed to telerobotics. If it works better, use it. I just can't get a dollar number on it, and I can on workers.
"have Congress charter an SSP company"
Darel and I have discussed this quite a bit. As someone else said in these comments, a lawsuit would stop the whole thing if it were done in the US.
"Then why is there no capital cost entry for fuel synthesis plants? High-temperature electrolysis and LOH/LOX storage aren't free."
Give me a number and I will put it in. I venture to say in the context of something this large the number will be small.
"not to mention spacecraft that fly twice a day, seems...unrealistically optimistic."
These things take off and land on runways. So do aircraft. Can you come up with a reason you can't fly one twice a day that doesn't also apply to aircraft?
"ground-based installations would probably be cheaper and certainly have vastly lower startup costs."
Ok. I have a startup cost of ~$60 billion and it replaces all the fossil fuel use in the world after a few decades. To get the US alone off fossil fuel and on solar would need ~2.5 TW. How much will that cost?
Want a reason? How about the fact that the Skylon vehicle must go thru reentry at the end of it's orbital flight. With the Space Shuttle, the heat shielding tiles must be carefully checked after each flight. What about the active heat shield which Skylon use to brake the craft during reentry? How long does that part of the vehicle last between overhauls? There are lots of unknowns in the design, the failure to solve any one of which would kill the concept.
The U.S. had a program to replace the shuttle using air breathing engines. The program was killed, last I heard, perhaps for good technical (not budgetary) reasons.
E. Swanson
Good links you found, but they don't support your argument that the craft would take more than a day or two to service and turn around. And even if it did, so what? All that does in increase the number of vehicles in inventory. The capital charges for keeping more in inventory are ~6 % of the value of one per year. If you fly one 100 times a year and they are good for 500 flights, that's 20% per year for wearing them out.
Years ago, when the company I worked with had a contract to work on the Boeing proposal for the ISS, we looked at automated detection of system failures. Along the way, we learned about the NASA Failure Mode and Effects Analysis efforts. The name rather describes the process, which was to sit around and try and think up what failures might occur during a mission and what the effects would be. In case of the Skylon system, what would be the effect of a loss of coolant in the Thermal Protection System? During the launch phase, a loss of coolant would result in a loss of the wing and a crash. Once in orbit, the craft could not be expected to survive reentry without that system, so the result of a loss of coolant would also likely be catastrophic (assuming the cooling were employed on reentry). The actual probability of such an event would not be known until a few vehicles had been lost.
Wanna bet that this system alone would be able to pass your rapid turnaround requirement?
E. Swanson
Sorry, I am the wrong person to get into the details of Skylon failures.
Reaction Engines makes a point of the vehicle having a viable abort mode throughout the flight. And to boot, cargo flights don't have to be human rated because they don't use pilots.
I just don't know enough detail about the Skylons to debate you on the topic. Maybe we could get someone from Reaction Engines to comment.
Loss of either wing (or both) with the engine(s) attached to the end would not present a "viable abort mode". I suspect that the Skylon vehicle would not return to land with one engine out, whatever the cause. It's that old stability in flight problem, you know. Haven't you learned to fly an aircraft?
E. Swanson
"would not return to land with one engine out"
"Abort capability: The vehicle is capable of flying
to and landing safely at strategically placed abort
sites with up to half its engines shutdown in a
similar manner to aircraft."
http://www.reactionengines.co.uk/downloads/JBIS_v57_22-32.pdf
"Haven't you learned to fly an aircraft?"
When I was 13.
As one with direct experience with aircraft, you probably understand lift-to-drag ratio and how that is related to aspect ratio. To achieve the greatest lift-to-drag ratio, the designer of a subsonic aircraft usually opts for long narrow wings, as seen in a typical glider. Commercial aircraft have such wings, which means that the lift to keep the craft aloft can be provided with minimum drag and thus minimum thrust. The wings on Skylon appear to be intended for supersonic speeds, being relatively short and wide. At subsonic speeds and low altitudes, the craft would require quite a bit of power to remain aloft, especially given that the full load of fuel and oxygen to power the craft during the rocket phase would still be aboard. The lack of sufficient power to overcome the drag would make level flight very difficult, if not impossible. Care to guess what the stall speed would be?
Also, the outboard position of the engines would result in a major yaw torque with either engine out and the vertical tail would need to be large enough to produce a torque at least as large in the opposite direction. Yes, I know that commercial transport craft with 2 engines are designed to fly with one engine out, but these designs have the engines located nearer the center of the craft, so the torque from drag on one dead engine and the torque from the still operating engine can be countered by the force of the vertical tail. I think the Skylon tail is too small to achieve this, especially at landing speeds where aerodynamic forces are at a minimum.
While the detailed description you presented speaks to pitch stability and the position of the wing CP and CG, there's no mention of yaw stability, which is most influenced by the fuselage and the tail. If the CG is near the front of the wing and the CP for the fuselage is at the usual quarter chord of an airfoil, the CP would be ahead of the CG, thus the vehicle would likely be unstable in yaw, even with both engines running. Again, the tail looks too small, IMHO...
E. Swanson
"Care to guess what the stall speed would be?"
No, because I don't like to guess and can't find it in the literature.
The takeoff speed is 155 m/sec, 347 mph. They have an interesting time stopping in the event of a rejected takeoff just short of rotation. To get rid of the heat without having many tons of brakes, they carry 1200 l of water. They do say that stopping one on landing is only 3.5% of an aborted takeoff. So it is going a lot slower than take off as well as being much lighter. I presume they land it under power, but probably not much power.
Although it doesn't have a lot of wing area, when empty, it's only about 50 t. Re the size of the tail, if you think it is too small, why don't you write them and ask? The contact email is on their web page.
That's rich. Most of the content of your original posting is based on unproven assumptions and other guestimates. Aren't you just being evasive to try to slide past a killer problem?
As for the potential to recover the Skylon craft after an engine failure during atmospheric boost, it's clear that the result could be a shutdown of the other engine and glide back to a landing. Since the fuel load for the rocket phase would still be on board, the mass at landing would be quite large, thus the stall speed would also be rather high, perhaps exceeding 275 mph, based on the speed you gave for takeoff. The result would not be the easy glide as seen in Shuttle landings and there would be no second chance...
E. Swanson
"unproven assumptions and other guestimates. Aren't you just being evasive to try to slide past a killer problem?"
No, the stall speed of a Skylon for various loadings is surely *known* from design calculations. I just could not find it. I don't mind estimating from physics when there has been little work on something, but I don't like stating something known when I can't back it up with a reference.
"Since the fuel load for the rocket phase would still be on board, the mass at landing would be quite large"
The brakes don't permit a full fuel load landing, it has to be dumped. A discussion of this is on the Reaction Engines web site. http://www.reactionengines.co.uk/downloads/JBIS_v57_22-32.pdf page 29.
I can't imagine that your concerns about asymmetric thrust from an engine being shut down have not been considered in great detail by the designers. The wings are short so the lever arm to an engine is not great, in fact, it looks to be less than you see on 2 engine passenger jets.
Henson wrote:
The quote you reference says this:
That quote says nothing about recovery from a catastrophic engine failure in the troposphere. At lower elevations, it's claimed that:
At lower altitudes, after a single engine failure or shutdown, it may not be possible to develop enough yaw torque with the vertical tail as shown in the graphic. Therefore, a tail the size of that on a 787 would be more appropriate, IMHO...
E. Swanson
"it may not be possible to develop enough yaw torque with the vertical tail as shown in the graphic. Therefore, a tail the size of that on a 787"
You may be right, though Reaction Engines' response indicates they have enough tail for yaw authority at low speeds. One thing that might make the difference is that it is going like a bat out of hell right off the runway. An engine failure short of rotation recovers using brakes.
I presume you are an AE. I am an EE and while I have wide experience outside that field, I don't know enough about aircraft control to argue the point.
"Maybe we could get someone from Reaction Engines to comment."
Mark Hempsell of Reaction Engines did. Here it is:
Skylon is the result of 25 years of work, dating back to the BAe HOTOL project. There is nothing in the baseline vehicle below TRL3 although there are a few "nice to have" like Expansion Deflection nozzles which we are working on that are below that. The current funded programme is aimed at taking everything on the engine to TRL 4-5 of which the ESA 1 million Euros is only a small part, most of the investment to date has been from private funding; in current dollars the total investment is approaching $100 million. The important point about the ESA money is that, although managed by ESA, it is UK Government money knowingly given, and there will be more.
It follows the development work we are currently doing is not laboratory scale proof of principle The main activity is the productionizing of the heat exchanger modules so we can make a full heat exchanger with frost control to test on our B9 facility. Our current plan (which will need some additional funding) is that within 3 years all the necessary technologies for the whole vehicle will be at, or very near, TRL5 and thus ready to make a decision on full development. I feel 2015 might be a little optimistic for start operations, our current programme says 2020 but I believe a couple of years might be able to taken out of that programme say 2018.
Abort Options: Skylon has the ability to abort the mission throughout the whole of the flight regime including one engine loss abort (depending on the nature of the engine loss). There are a few special tricks that increase the resiliency such as using the spill duct burners alone in a supersonic cruise, it is also worth remembering that the remaining working engine has considerable control authority in pitch and yaw we are not relying on the aerodynamic surfaces alone. Aborts have been looked at independently by two teams and the only point of contention is whether there is a gap between "turn and return" options and "once round" options which might introduce a requirement for a downrange landing site.
Reliability: There is no compromise on the reliability in automated flights partly because of the value of the Skylon vehicle and partly because the automatic flights are part of the on going certification of the crewed flights. It should also be noted we have assumed a certification route to safety and not a man rating route (the difference being in one you certify the vehicle in the other you certify the crew). On entry into service the mission loss rate will be better than 1/1,000 and vehicle loss 1/10,000, but as with most parameters if it were being run in an operation as large as SPS these figured would be much better (simple Weibull).
Wing and Control surface sizing: The C1 configuration has under gone wind tunnel testing up to Mach 12 and some basic CFD over the entire flight regime. We are confident it has lift and control over all flight regimes. It helps to remember on the way back that the main fuselage is basically a hydrogen airship which means our instincts, based on normal aircraft, as to what looks right is wrong.
Thermal control: the lower ballistic coefficient means the temperatures during re-entry are much lower than the Shuttle and we do not need ceramic tiles (and the original Shuttle concept with integral propellants tanks also did not have the tiles they were a result of the move to an external drop tank). The Skylon aeroshell is a proven and available reinforced glass ceramic material (which is why Skylon is black). There are two areas of active thermal control, one around the canard root and the other on the wing where the shock/shock interaction occurs and, yes, if they fail during re-entry we will loose the vehicle.
Flight Rate: if the space port is equatorial then launch windows to any LEO facility occur roughly once every 90 minutes and a single runway spaceport could easily launch a Skylon at every opportunity. Any particular Skylon vehicle could manage a flight every 2 days but it might be possible to bring that down. The development test programme for the Skylon proves the vehicle for a 200 flight lifetime but in mature operation that could probably be extended.
Atmospheric Pollution. There is a few small amount of nitrous oxides produced during the airbreathing stage and some damage to the ozone layer as Skylon flies through it (mostly from the exhaust water). But Skylon is though the layer in a matter of a few seconds if a problem can be minimized by altering the trajectory with some loss of payload. These would need to be assessed in any environmental impact analysis but even with the flight levels needed for an SPS programme it is low compared with current civil aviation.
Passenger Capability: A passenger module that can carry between 20-30 passengers would be a part of the Skylon development programme and would cost around $150 million each. The average cost per passenger we estimate to be around $1 million but with the traffic levels needed by an SPS programme the cost would be much lower – maybe as low as $100,000 per person.
"if the space port is equatorial then launch windows to any LEO facility occur roughly once every 90 minutes and a single runway spaceport could easily launch a Skylon at every opportunity."
Adding a bit, for the geometry in Figure 5, where the goal is to reach a GEO production facility instead of LEO, the launch window is away open. Eight takeoffs and landing an hour is far below the flight rate of major airports and would support a cargo rate of 100 t/hr. Without more lasers in space or on the ground at a different location, the laser stage has to go around the transfer orbit 1 and 1/2 times. With 1.6/14 x 8 GW in space, a laser stage can be circularized on the first opportunity. Between that and draining the Van Allen belt, passenger traffic to GEO would be safe and fast (5 hrs).
Wait, you're making cost claims on the basis that anything you can't find a number for is free? How is that even remotely reasonable?
Your proposal only looks cheap because you're ignoring almost all cost sources.
Are you serious? How about the obvious: exceeding Mach 5.5 en route to rocket-assisted orbit.
If you insist on comparing to airplanes, the closes comparison is high-speed, high-altitude spy planes. From what I've heard, the Blackbird required much more maintenance than the lower-speed, lower-altitude 747; why do you suggest that a vehicle which goes faster and higher than a Blackbird would have maintenance requirements more similar to a slow and low commercial aircraft?
This craft is going to have far higher thermal and atmospheric stresses than a commercial aircraft, and that's not even considering the stresses associated with the rocket engine (hydrogen embrittlement, etc.). If you're assuming the craft will require no more maintenance than a commercial aircraft, your assumptions are not reasonable.
Sometimes as here Pitt gets to the pith and more than compensates for the muddles he manages in some of his other posts.
Since the late 1950's, following encounters with writers such as N. J Berrill and Charles Galton Darwin -and later Garrett Hardin - I have suspected that there might be a population overshoot followed by a dieoff. This prompted me to become active in organizations such as The Population Reference Bureau, Planned Parenthood and eventually Zero Population Growth. At no time did I WANT to see a dieoff. The following is an excerpt from The Tragedy of the Commons,
"A finite world can support only a finite population; therefore, population growth must eventually equal zero. (The case of perpetual wide fluctuations above and below zero is a trivial variant that need not be discussed.) When this condition is met, what will be the situation of mankind? Specifically, can Bentham's goal of "the greatest good for the greatest number" be realized?"
Did Garrett Hardin want a dieoff? Did Georgescu-Roegen, L.F. Ivanhoe and most of the other other authors cited at http://www.dieoff.org want a dieoff. Granted you can probably find someone somewhere who wants a dieoff. Nevertheless I believe that the following claim is disgusting and warrants modification - perhaps even an apology.
"Of course lots of people seem to *want* low energy world, including a population die back to one or two billion people."
At no time did I WANT to see a dieoff.
And there is a difference between "wanting" and pointing out this is the most likely fate of Man.
If anyone WANTS a population reduction they can take something like UG99 and go from cropland to cropland in the various nations spreading it. A more expensive and higher level of training would be buying the DNA 'printers' and making (or remaking) a virus. Posting on the Internet "I want a population reduction" isn't really effective for the reduction action plan.
Hiding behind the distinction between wanting die-off versus expecting die-off, there's a more important point failing to be mentioned.
Supposing Keith gets this vast energy supply fully working. Result paradise? I doubt it. More likely people dump their Hummers for personal heli-Hummers, and the world population jerks up to 12bn. And the ecosphere gets utterly trashed in consequence. If there are any survivors they survive on a planet devoid of trees and fish, let alone happiness. So, near-term die-off is probably the least worst option anyway.
(...)
So let me get this straight. Your post amounts to an innovative manner of getting the components into orbit in order to reduce the costs of the system and thus make the bottom line levelized electricity costs look better? But it assumes that the basic system itself, the idea of using large solar collectors and then beaming the power down with lasers to receivers on Earth is pretty much worked out. Ready to go. A realistic and credible approach? Even taking the efficiency of the lasers that do the power transmission into account? And the challenges associate with the receivers?
Lasers are for getting parts up, not for getting power down. That would be by microwave, same as Peter Glaser proposed over 40 years ago. And yes, it well understood physics and engineering. Realistic and credible enough that PG&E signed a contract with SolarEn for 200 MW back in April. The receivers were demonstrated back in the 70s at Goldstone. http://en.wikipedia.org/wiki/Microwave_power_transmission Good questions.
Ever heard of "bull shit"? That PG&E contract allows them to say they have met the requirement for renewable energy, at least until the date of delivery on the contract. PG&E pays nothing of the cost of the development (as I understand it), so it's no skin off their nose if the guy working out of his home office can't actually deliver on the contract. The fact that microwave energy can be transmitted and received has only been demonstrated over a distance of 90 miles at 20 watts, so one must not bet the farm on a big leap in faith to a level of gigawatts from GEO to the surface...
E. Swanson
"The fact that microwave energy can be transmitted and received has only been demonstrated over a distance of 90 miles at 20 watts, so one must not bet the farm on a big leap in faith to a level of gigawatts from GEO to the surface..."
There is not a microwave engineer in the world who would have the slightest doubt about transmitting GW from GEO to the surface. We are already transmitting down hundreds of kW from communication satellites. We just are not doing it for raw power.
Your glib reply ignores the fact that there's a massive difference between transmitting microwave energy to a receiving area the size of the U.S. and a receiving area of about 10 km diameter. Not to mention the problems on the other end of the link at the transmitting antenna. Get a grip man!
E. Swanson
It's simple math, based on physics over 200 years old.
sin theta = 1.220*lambda/D
The little antennas on communication satellites radiate widely. To get it down to 10 km spot on the ground takes a 1 km transmitting antenna at 2.45 GH phase locked like a laser to a pilot beam coming up from the rectenna. It is exactly the same way ten story high, phased array radars work. It's not in question that it will work.
http://en.wikipedia.org/wiki/Space_solar_power#Spacecraft_sizing
http://en.wikipedia.org/wiki/Rayleigh_Criterion
http://en.wikipedia.org/wiki/Airy_disc
http://en.wikipedia.org/wiki/George_Biddell_Airy
Sorry if I seem glib about this. There are lots of practical problems to solve, but microwave transmission is not one of them.
I sort of agree with you, there have been lots of studies looking at microwave power transmission, but scaling up might show up difficulties which the many theoretical studies have failed to address.
Exactly - I see roughly 100 wrong/error prone things that could happen to this "Scientological Solar Hype Thing never to happen BTW"-thing. But starting up scratching one of them, makes people like Henson go into overdrive ... linking to more and more "maybe-if-and-ifnot-then"-links never possible to conclude upon.
This very "Solar Satellite Power with Laser Propulsion"-concept is based on 1000 unknowns- and there it sits, well embedded in the quagmire if I may add..
Researchers Beam ‘Space’ Solar Power in Hawaii | Wired Science | Wired.com
20 watts 92 miles. Most of it was lost in transmission too.
Sure this could be scaled up - make a helluva Weapon of Mass Destruction, too. I prefer Staniford's global grid, as far as contemplating the ne plus ultra of power generation. He didn't leave out economics, although some balked at his projection of global GDP in the trillions, natch.
Yeah,I believe the safest place on earth - "when" pilot-testing is due , will be "on the other side" of the planet. I foresee some "French-fries"- or "McNuggets"-engineers nearby the receiving antenna.ha ha.
Thanks Gail for distributing "this one" one more time
Space Solar Power is the pinnacle of idiocy IMHO.
Of cource it belongs on TOD ,but only so that it can be debunked and put to rest once and for all.
If I'm not wrong (and from top of my head) solar intencity is only double outside the atmosphere - compared to down on earth - only twice as much energy per sq. area that is ... so - and all other impossibility issues exempted - will these "Space Solar Power"-arrangements end up at less than twice the cost of equal collectors (per area) on the earths surface ? No of cource they wont, and therein is the short answer : Forget about it !
It's well worth being skeptical, paal, but you oversimplified by a factor of four or so, at that rate.
The space collectors would also benefit from 24 (or nearly 24?) hour exposure to the sun, and would never see a cloud. Don't know what kind of 'sandstorms' they might have to endure, however.
As with Fusion, I don't begrudge our having a few people doing research out on the fringes of current technology, in fact it would be foolish not to... but we'd better have some decent proof-of-concept before we put public money in for the production model.
Bob
You are of course right here Bob. But my core approach in my reply is the already known and understood lack of (order of magnitude) possible gains for this venture. Already, "from the back of the envelope", we know this will cost alot and yield so little.Why bother ? Why is Keith Henson elaborating on space-crafts for this utopical never to happen project ? Why is he not writing poems instead ? - or perhaps that is exactly what he is doing , writing techno-poems!
As for fusion power, I partly agree with you.
At least this has alot of claimed promise, if they against all odds make it happen
Good luck to them- but hopefully they don't put the atmosphere on fire ..
Paal, putting solar collectors (most likely steam turbines) in space is just putting them where you can get the most sunshine. And up to this proposal, we indeed knew it would cost a lot. If you work though the math, and I have, then power satellites make sense when the cost to transport the parts to GEO gets down to about $100/kg (currently $20k/kg). At $100/kg they make electric power at such a low cost that fossil fuel use goes away simply by being under priced. The lowest lift cost to GEO you can get from physics is 15 cents for the energy and a capital charge of perhaps ten dollars. This rocketplane and laser method isn't that good, but it's good enough.
I am surprised nobody has brought out the really sticky problem yet.
So you know something that we don't ? :-) please tell..
And as for your "math", not to be rude , but I don't believe you. OTOH I believe this kind of utopical-concept will stay fixed on the backside of that very envelope or on the HD of your computer and now here on TODs archive. But here it ends. Energy concentration/area up there is simply to low, is this so hard to grasp?
Further more such a project will become "chewed up and spat out" by a bugger named Mr. Receding Horizons - in short your "good math" today will turn to "bad math" tomorrow. Here is an example from a regular infrastructure in Norway - http://no.wikipedia.org/wiki/Sotrabroen (text in Norwegian) .. but I will elaborate my point here -
a) There is one existing old bridge, finished back in 1971 costing NOK 40 million.
b) due to traffic jams during rush hours there is a new one on the drawing board (2009) estimated to cost NOK 4.1 Billion.
Thus, 40 years span in time increased the more or less same infrastructure MORE THAN 100 -houndred- TIMES.
Q Keith : Have you done "the math" for your project starting .... ehh ... say 2020 ?
"So you know something that we don't ? :-) please tell.."
It's mentioned in the article.
"And as for your "math", not to be rude , but I don't believe you."
I can go though it line by line if you want. For example, 365 days/year * 24 hour/day is 8760 hr/year. 90% of that is ~8000 hr per year, ten year payback is 80,000 hrs. At 2 cents per kWh, this is an income of $1,600 per installed kW. That's means that if a power company wanted to sell power at 2 cents per kWh they could pay no more than $1.6 B per GW. (Ignoring maintenance cost.)
A reasonable number for power satellites is 5 kg/kW. If you allocate ~1/3 for transport, then the transport can't cost more than ~$500 or $100/kg.
With me so far?
Re the bridge, 40 million to 4 billion is a factor of 100. That's even worse than the I35 bridge that collapsed in the US. The original was $5.2 million and the replacement was $234 million, a factor of 42.5.
Eh, I'm still at the stage where you base your whole enterprise on a wholly unproved technology from a company whose website you deign to even provide a link to, which will provide vehicles the size of 747s which you are wholly confident they can do, simply because "Boeing built 747s at higher rates."
Now I'm lead to the conclusion this is a gag. April 1 was a couple of months back. Why not wait for Highlift to build space elevators? Only $15 billion according to their PR. That's less than a major automaker bailout.
Sorry to be snide but isn't this all predicated on altogether fantastic assumptions of various stripes, not least the means to secure any funding for such an out-there approach? Don't tell me that I'm assuming people won't pony up; Bill Gates dumped $100 million into Pacific Ethanol, even the world's richest man is a potential mark.
"whose website you deign to even provide a link to"
Sorry, here you go.
http://www.reactionengines.co.uk/
http://en.wikipedia.org/wiki/Reaction_Engines
Re building them, Reaction Engines is a design firm. I suppose they could build them, but it's more likely that Airbus or Boeing would build them under contract. The point is that industry could do this scale of work four decades ago. http://en.wikipedia.org/wiki/Boeing_747#Deliveries
"Why not wait for Highlift to build space elevators? Only $15 billion according to their PR."
Space elevators are a risk factor for whoever does this. Though we don't have the cable yet, it's possible they could be built and would under cut a Skylon/laser method like cell phones ruined the business model for Iridium. The propulsion lasers would make short work of cleaning up the space junk that otherwise makes a space elevator a dicey proposition. Google,
A 2000 tonne per day Space Elevator ESA Conference presentation Feb 2007
"not least the means to secure any funding for such an out-there approach?"
I am a technical guy. I freely admit I don't have the least idea of how such a project could be financed. But at ~$60 billion it's not that far out of the range of projects, particularly energy projects, that already *have* been funded.
Good questions, sorry I don't have answers for all of them.
Okay ... taking a few minutes off from my 'turning lead into gold' project. I should have a few pounds of gold by the end of next week ... oops! There is the warning buzzer telling me I better get over to the fusion in a mayonaise jar project I have set up in the basement. I have to be careful since the gigajoules of energy potential in that mayonaise jar could blow up the entire neighborhood ... thanks!
Let me see ... if I remember right it took a long time to design and build the low- orbit space shuttle. Billions, plus $60 billion 1970 (pre- inflation) dollars to travel to the Moon - and back, of course. There is the Eurofighter and the F22 @ $800 million for EACH aircraft and the B2 @ over $1 billion for EACH aircraft. I would say double the cost estimate and more than double the time required. Of course, too much time invested and the costs would really skyrocket.
Get it? Rocket!?
Then, there is the issue of it working ... at all. It would be a 'bummer' if the microwave beam dissapated in the atmosphere ... or the microwaves accelerated climate change or a glitch caused the flying 'Grand Coulee Dam' to incinerate Manhattan or Beijing. Shtuff happens ...
Leaving alchemy and portable fusion aside, the only way to solve in any manner our energy situation is with a desperate and ruthless honesty. The time for dreaming dreams is over. Results matter.
Conservation works. How about $68 bazillon spent on coservation?
Conservation is the easiest, best, always works, never failed, will be 'imposed' by circumstances anyway.
There are more alternatives that need investment that are more prosaic. Dams, windmills, geothermal, tidal, etc; combined with using less, the power output would be identical and far less costly than a large (and trouble prone) orbital space station.
The secret to all alt energy schemes is decentralization. This project has monopoly written all over it. Monopolies create waste. They also drive costs into unprofitability. Look at OPEC! Two cents a KWH? No way!
Energy in space doea work. Fine ... lets let the methods evolve. It would be better to see some space based power beamd to the surface from low earth orbit first, then see if there is an energy return on the investment. Perhaps an experiment could be attached to the space station. If the return is sufficient and scalable, perhaps space power can support ... the space program, itself!
I'd rather see a sustainable energy program that would self- support agriculture. This priority first, then worry about space. Flying to Mars sounds like a great adventure and very inspirational, but having enough to eat in the years ahead is more important ... MHO
"I'd rather see a sustainable energy program that would self- support agriculture. This priority first, then worry about space. Flying to Mars sounds like a great adventure and very inspirational, but having enough to eat in the years ahead is more important ... MHO"
I agree. One of the things you get from abundant low cost energy is fresh water. That's by far the most important thing in growing food. Really low cost energy, down in the 1-2 cents per kWh, will let you make salt water into fresh and pump it inland for a thousand miles.
Ummmm ...
Yr giving me too easy a shot at you. I don't think yr project has a chance of producing cheap power anymore than it has a chance of providing swiss cheese. You know what I mean?
It costs millions of dollars to launch a garden variety com satellite into low earth orbit. People have been launching rockets for centuries. It's not rocket science any more.
The Germans built rockets that could come close to orbital velocity in the early 1940's. That's seventy years. If the best we can do in seventy years is a multimillion per launch for a relatively small payload, the launch limitations are probably non- negotiable. Even in the US a million is a lot of money.
"It costs millions of dollars to launch"
Once you factor out the government welfare program, it is worth figuring out why it is so expensive. The reason is rooted in the rocket equation. Take a look at the first two figures.
Rocket engineers have known since before the V-2 days that low exhaust velocity is the reason rockets are so big and deliver so little to orbit. Laser propulsion has been studied a long time too. Its drawback is small payload. As far as I know, this is the first time anyone has proposed combining rocket lift for the first stage and laser propulsion for the second.
It looks like it will deliver 5 times as much payload for the same cost.
The Skylon single stage to orbit is an unproven concept. Until the system is designed, built and tested, it's a pipe dream. Recall that the Space Shuttle was supposed to be a "Space Truck" that would provide both cheap launches and rapid turnaround to enable movement of lots of mass into LEO. Didn't happen and the fact that the technology had problems only became obvious well into the program after the Challenger accident. Please remember that the Space Shuttle used engineering concepts which were well known to work, as demonstrated by numerous rocket launches and the entire previous space program, although the particular combination of elements was different than in previous systems.
As for building a "2000 tonne per day Space Elevator", consider that lifting only 1 ton (2000 pounds) away from the launch site at 100 mph would require 533 horsepower. How much more mass would need be added to the lift vehicle in addition to the mass of the payload?
That calculation assumes a lift speed of 100 mph, which would imply that time to reach GEO would be about 230 hours, roughly 10 days. Thus, to lift 2,000 tonnes per day would imply that the lift vehicle would wither need to carry 10x2,000 tonnes or that there would be 10 lift vehicles with 2,000 tonnes payload each. Either way, the force on the tether at GEO supporting all this mass would be 10x2,000 tonnes mass at appropriate distances from the Earth or perhaps 1/3 of the 20,000,000 kg total (I haven't worked thru the details).
These look like big problems to me, if only because of the need to provide the power for the lift motors.
E. Swanson
What will be the heat sink? You will have to reject heat somehow and the vacuum of space is a pretty fair insulator.
I thought that studies have shown that heat engines are not the most efficient for SPS, mainly because of the large mass required for heat rejection and partly because of the increased maintenance costs.
PV cells are ~15% efficient. A decent two stage Rankine or Brayton/Rankine setup will get 60%.
It's not known how long rotating machinery will last in space, but they last 50 years here on earth.
I am not opposed to PV cells, or for that matter anything that will get the job done.
"What will be the heat sink?"
Radiation, it's the same way earth ultimately gets rid of heat. Rule of thumb is 1/4 kW/m^2 per side for room temperature. Takes a square km to get rid of half a GW of waste heat.
Dr. Eric Drexler and I worked this out way back in the 70s in the context of keeping a space colony from cooking. The most massive part of big radiators is the fluid in the radiators. In a flash of inside Drexler came up with decoupling the pressure of a gas from the amount of heat it could carry by loading the gas with a lot of solids, i.e,, a dust filled radiator. In zero g there is no reason for the solids to separate from the gas.
I don't know how well that will apply in space. The "room temperature" qualifier suggest that the rule of thumb was arrived at in terrestrial conditions. The Stephan-Boltzman Law will probably determine how much heat you can reject in space, and its strongly temperature dependant (proportional to T**4). With an efficient cycle you have to discard the heat at lower temp, you'll need 16 times the radiative area for a sink at 700K than you'll need at 1400K.
"the rule of thumb was arrived at in terrestrial conditions." The law applies everywhere.
P = area * emissivity * 5.6704 10^-8 * K^4 (Ignoring the back radiation from 2.7 deg K background)
For an area of one square meter, e of .9 (not hard to get) and 273 deg K, P = 283 Watts.
Round down to 1/4 kW/m^2 for conservative engineering and to allow higher drops in the heat exchangers. If you want to keep the air temperature in a space colony in a nice temperature range with passive radiators, starting with freezing cold heat sink filling is a good idea.
Ok, I see now.
Using a similar design to the radiators on ISS would require at least 158,000 tonnes of radiator (not including some support functions). Which is rather more than the 5,000 tonnes allocated for the whole power sat.
Most heat exchangers provide the cooling by the phase change from liquid to gas, a low mass of gas means a low amount of cooling. What heat exchanger technology were you planning to use? Has this been demonstrated to work? Moving dust has many potential problems including abrasion, clumping and clogging. A mass reduction of 30x would have been a powerful incentive for use on ISS where mass limits were very tight, why did they not use it if it gives such a large advantage.
"Using a similar design . . . least 158,000 tonnes of radiator"
I wish you would show your work so I didn't have to re do it.
2470 pounds is 1122 kg / 11.8 kw is ~95kg/kw. Or 95,000 t per GW.
1GWe is 2 GW at the power sat feeding the transmitter. At 60%, the thermal input is 3.3 GW and the waste heat is 1.3 GW. I get 126,000 t. I wonder where we differ in assumptions?
I wonder why they used ammonia? If they quit heating the heat sinks, it will freeze at -77 C and be impossible to restart unless they can turn it to where the sun heats it.
In either case, this is one of the reasons NASA should not be involved.
"Put the atmosphere on fire"? From nuclear fusion reactors? The whole problem with controlled nuclear fusion is keeping the reaction going, particularly in such a way as to produce net energy. As soon as the plasma touches anything outside of its confinement area, such as a wall, the process stops in its tracks. There is no possibility of any kind of runaway reaction.
MW, regarding "Put the atmosphere on fire" : keep the myths alive!
Also I see Keith Hensons faith in cryonics as a myth - until further notice
Humm....isn't Methane more of a concern as a GHG than CO2?
But on a more substantive note...what are the assumptions behind the process that uses "50 times as much energy"? Does it take that much to grow algae? Algae has already been engaged in CO2 capture so why would we concern ourselves with a "high-tech" solution with such a massive redirection of resources????
Algae Sequestration
A recent article shows that many are working on Algae as a solution to both energy and CO2 capture. I keep hearing and reading about earth injection strategies but why?
Oil CO2 & Algae
IMHO, this proposal seems an overly complex engineered solution that poses a significant design challenge resulting in a massive reallocation of resources on a fools errand....in other words, another government sponsored boondoggle. (oh, and how do those lasers penetrate a cloud?)
Yes. No. It has a more potent warming effect, but its atmospheric concentration is also much less. Its also short lived, a half life of around eight years. CO2 half life varies, but is several times that of methane on average. If we ever reach a tipping point in tempature to where methane is released from hydrates, the ensuing negative feedback loop will be what does us in.
"the ensuing negative feedback loop will be what does us in."
Yet again we see the misunderstanding of "Negative Feedback". A Negative feedback loop controls or minimizes a situation, whether that situation be good or bad. It is "Positive Feedback" that will be the problem with methane hydrates, as the "bad news scenario" is amplified.
Thank you sir, you caught me being sloppy with verbiage.
With all respect, the notion of halving the development time by doubling the budget is questionable.
My reaction on high power lasers, having worked with only moderate power ones, is that there are little issues of reliability and life time. You can get a laser up there, perhaps, and it may even work, but only for a while.
It is possible to look at solar availability in sensible places to build solar collecting power installations, for example, for Europe, central Algeria. It's very good. The night storage issue is more serious. For solar concentrating heat storage, there are several options. The Victorian engineering (stacked fire bricks) is fairly inexpensive.
"You can get a laser up there, perhaps, and it may even work, but only for a while."
The lasers stay on the ground where you can work on them if you must. Look at Figure 5. Laser beams go up, bounce off focusing mirrors at GEO and come down 45 degrees to the east on the equator. They track and power the laser stage as it accelerates. By the time the stage goes over the limb of the earth, it's moving fast enough to be in a Hohmann transfer orbit to GEO.
That's three who misread the purpose of the lasers. Should have worked in a short section on how power satellites work. Appreciate the feedback.
While you are adding information about ground based, high power lasers, please include the effects of atmospheric dispersion on your laser beam to GEO and what that would do to the intensity at the receiving end...
E. Swanson
I am not a laser expert. The laser experts such as Jordin Kare are not concerned about the relatively low intensity beams going up through the atmosphere because the intensity is below where you get thermal blooming. It still needs active mirrors. I really wondered about the Fresnel focusing mirrors at GEO, but again they seem to be confident. The tracking problem is less of an issue than big telescopes use.
Very little of the technical work is mine, I just stuck what is known or proposed together and run the economic model.
Gail -
It's been my impression based on your various recent comments on TOD that one of the reasons that you are generally down on wind power is that you believe that the manufacture, installation, and maintenance of wind turbines will become increasingly difficult in a future world beset by energy, materials, and financial constraints. Am I correct (or at least close)?
Yet, here you select for presentation on TOD this article touting the old solar satellite concept, a fantasy that will require the construction of scores of launch vehicles of Space Shuttle like proportions, many thousands of round trips to orbit and back, and lord knows what other super high-tech support facilities, in an undertaking that would dwarf the Apollo Project, in size, scope, and cost.
So then, are we somehow supposed to believe that wind power is too high-tech to be sustainable, but this sci-fi monstrosity is not?
I just don't get it!
Although I like this idea from a 'blue sky' standpoint (my inner cornucopian), it does suffer massive credibility gaps when we can't even get our act together to put white metal roofs on structures to reflect heat and lower cooling loads and to install PV on these same structures (residential, commercial, and industrial) to have energy during the day and learn to go to sleep when the sun goes down. I would bet on 400 new generation fission reactors before I would imagine SBSP becoming a grand-scale reality. And this is from a huge fan of space exploration, sci-fi, and so forth. Yes, and wind turbines are a proven technology being hamstrung by vested interests such as the coal industry.
I am not sure we are good at predicting what will and will not work.
It is very difficult to scale up wind power to the level we would need to replace a large share of fossil fuels. This week, I believe "aeldric" will be presenting Parts 3 and 4 of an analysis done for Australia relating to replacing fossil fuels with renewables, particularly wind. I have not seen parts 3 and 4 yet, but understand that the cost is forecast to be very high, and there were other obstacles. I expect the situation would be similar elsewhere.
Additionally, maintaining wind turbines and building new wind turbines will be very difficult, if the amount of fossil fuel decreases greatly, because of the need to maintain roads and other infrastructure in order to keep servicing the wind turbines.
It seems to me that we should be keeping our eyes and ears open for things that might be scalable to the point that they might make a big difference. I am sure there will be blind alleys, but we should still be looking.
Building new anything will be difficult if the amount of fossil fuel decreases greatly, for sufficiently large values of "greatly". There's no utility in singling out wind; soda pop production and pie in the sky solar will feel the shortfall just the same. Being in orbit offers no advantage to accessibility, if we'll have the productive capacity to maintain installations in orbit we'll have to productive capacity to dispatch dirigibles/helicopters to remote wind installations.
Besides that wind turbines require little maintenance, all this maintenance equipment can be powered on natural gas.
which according to you seems to have good prospects:
http://www.theoildrum.com/node/5459
Gail -
I think you are being somewhat evasive regarding my basic question.
You seem to have arrived at a fixed conclusion that wind is no good. And one of the reasons you give is that it would be difficult to scale up wind power. But in the same breath you appear to be saying that having multiple launch vehicles making thousands of round trips to and from outer space would have no scale-up problems?
If maintaining a wind turbine (a relatively simple mechanical device) a few miles off shore is so difficult, then why wouldn't it be many times far more difficult to maintain solar satellites that are several thousands of miles up there in outer space?
And as far as the problems of maintaining the necessary infrastructure are concerned, if roads and other things are going to be a problem with wind power, then why wouldn't maintaining the infrastructure needed to maintain the launch capability of several score of equivalent space shuttles be many orders of magnitude worse?
Gail, you can't have it both ways. If wind is no good for the reasons you have stated, then this solar satellite scheme is many times more no good for the exact same reasons.
Again, what you are saying appears highly inconsistent and, quite frankly, makes no sense to me.
Wind power or ground solar have severe storage problems - if you plan to store it. If you use it on site, for example, that problem goes away:
Ammonia from Wind Power – The University of Minnesota - West Central Research and Outreach Center is configuring a system to convert wind energy into ammonia. The approach uses the wind power to drive a water electrolysis system to produce hydrogen and an air separations unit to take nitrogen from air. The hydrogen and nitrogen will then be combined in an advanced catalytic reactor developed at the university. The goal of the project is to produce ammonia, either for fertilizer or fuel, which is cost competitive with fossil-fuel derived ammonia fertilizer or fuel. (Contact: Mike Reese, University of Minnesota - West Central Research and Outreach Center, 320-589-1711, reesem@morris.umn.edu) - http://www.ammoniafuelnetwork.org/projects.html
Space solar, however, is 9.6 times efficient than putting PV panels on your roof. At GSO it creates 9.6 times as much power per day as that same panel at an average US location. As fossil fuels become more expensive and polluting, the appeal of space solar increases. The energy return on energy invested is higher for SSP than any other energy alternative we know of - which ultimately means it costs less. The problem is getting it started, because the physics of wireless power transfer dictates huge antennas at both ends. So the financing is like building Hoover dams in the sky - huge government-scale expense but very low operating expenses. And it must be gigawatt scale or the low efficiency makes it uneconomic.
The JPL Goldstone microwave wireless power transfer demonstration recorded 84 % efficiency in 1975. 30 kW was successfully transferred from the transmitting large parabolic antenna dish to the distant rectenna site over a distance of 1.6 km. We expect about the same transmission efficiency - GSO to rectenna - if a system were built starting today.
If 10 GW is output from the PV panels at GSO we expect 5 GW would be injected into the power grid. Another key is that SSP only outputs about 20% of the waste heat as a standard coal plant does - not to mention no CO2, which means it is extremely climate change positive - a win-win-win.
Actually, electricity generated from Wind and PV can easily be used to generate heat energy and 'cool-energy' with efficient heat pumps.
And storing heat-energy and 'cool-energy' is cheap and easy.
And actually, significantly more energy in a household is needed for cooling and for heating purposes than for any other electricity needs which are not replaceable by heat or cool-energy:
Besides that you need proof for this claim.
More important than the efficiency of a PV cell is the energy input per Watt which is significantly better with thinfilm amorphous silicon cells (efficiency: 7%) than with high efficiency cells typically used on power satellites.
Also, as opposed to space solar, roof-PV does not only reduce peak load, because it never produce power at night when demand is low, it also reduces grid load because as opposed to Space solar it is distributed power.
re: "9.6 times as efficient"
These guys have to stop talking this way. So far, there is a 30kw, 1-mile transmission test, and a lot of complicated technological links that still have to be proven.
There is NO space power that can compare today to the measly 85 watts that sit on my roof, even under clouds, I'm getting ~some~ power from the system... I could very easily charge my cellphone and every flashlight in the house from this miserly output.. it's humble, but very reliable.
They are talking like their paper-model is already flying.
Bob
Beware of what you are saying jokul... I can't actually recognize Henson with a helmet though.
As requested -
9.6 times more sun (and revenue) in high orbit
How much total energy or power per year would a terrestrial PV collector of a given efficiency and size collect here on terra firma versus GSO? We are not comparing peak PV power, when the sun is high on a clear day, rather the annual or daily (integrated) average power. The best research we can document (below) says that number is very close to 10 to 1 for the average US site (and also for Japan, the PV leader, where most of the world's PV is installed, since we are at similar latitudes).
Using NREL’s standard tables as listed at
http://solstice.crest.org/renewables/solrad/data/index.html
Another source is
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/serve.cgi
Solar Radiation by City for Flat-Plate
Collector Facing South at Fixed Tilt = Latitude
Major US Cities Average
kWh/m2/day
Los Angeles, CA 5.6
New York, NY 4.6
Chicago, IL 4.4
Washington, DC 4.6
San Francisco, CA 5.4
Detroit, MI 4.2
Philadelphia, PA 4.6
Boston, MA 4.6
Dallas, TX 5.4
Atlanta, GA 5.1
Houston, TX 4.8
Seattle, WA 3.7
Miami, FL 5.2
US Average 4.78
Therefore, multiplying by 365 days, the total power per year for an average US site is
1745. kWatts/m2 per year for Flat-Plate Collector
Now up at GSO Solar Radiation is more intense at 1.367 kWatts/m2 ,
so multiplying by the hours in a year, we compute 11930. kWatts/m2 per year
(GSO orbit means the sun is in shadow approximately 33 hours total per year - at midnight during the equinoxes, so we actually used 8760 minus 33 = 8727. During these times of eclipse, GSO satellite operators, like NOAA, usually provide power to the satellite with batteries.) Therefore solar radiation is
6.84 times brighter at GSO.
(What about sun tracking? If sun tracking is added to any solar array location, the collected power increases by only 20%, moving the US average power to 2095 kWh per year, which would reduce the expected advantage of GSO to 5.7. However, this substantially increases the operational costs by using power and increasing maintenance, so that extremely little installed PV capacity actually tracks the sun; it is not cost effective, they are usually roof mounted like shingles. By comparison, in space, such as GSO, sun tracking is nearly always done.)
Based on the best studies available, by Texas Utilities's Electric Park, the expected (nameplate) rating for their PV system was predicted to be 140,000 kWh however their actual production was close to 100,000 kWh. The cause was attributed to summer heat, smog and haze. Based on their studies, the typical US average advantage of GSO over terrestrial PV solar energy collection would be
6.84 * (140/100) = 9.6
and probably a bit higher since Texas (and TU’s Electric Park) is a better PV site than average US sites. (See EPRI Tech Report -106409 or RS-106409 for further details of TU’s PV study.) More important, from TU's actual system studies was the fact that peak PV performance coincided with early spring or late fall when electric system power use and demand was at annual lows.
It would be much preferable for peak power output to occur in the summer, or at least winter, since these are the peak energy demand periods. A Kilowatt-hr in summer is more expensive, or valuable, than a Kilowatt-hr in spring or fall. GSO production is again better than terrestrial because production is steady or flat throughout the year.
Fully evaluating this impact is a topic for further study of a particular regional market, but you can check your own summer electric power bill rates against spring rates. This is definitely a negative impact on terrestrial bottom line power availability, value and the corresponding revenue. This negative attribute of terrestrial solar is also shared with wind power.
Many other minor details could be mentioned. For example, PV on earth sees a slightly different power spectrum than at GSO. This means that even more energy is actually available at GSO – if the PV at GSO were tuned to capture it. Terrestrial PV cannot hope to capture energy which does not penetrate the atmosphere.
(To compare the relative performance of different PV designs, standard spectra have been defined which approximate the real solar standard spectra. PV is tested and rated at Air Mass numbers – AM0 is what PV would receive in high orbit, like GSO, with no atmospheric cover, whereas AM1 means a normal – sun directly overhead at sea level – air mass cover. AM1.5 is officially defined as the “solar spectral irradiance distribution (diffuse and direct) incident at sea level on a sun-facing 37-degree tilted surface, with atmospheric conditions of: precipitable water vapor, 14.2 mm; total ozone, 3.4 mm”50)
We should also consider the effect now known as "global dimming". Many scientists have measured the loss of sunlight at about 2-3% per decade in different regions during much of the last half of the twentieth century. This has been concentrated at the northern and mid latitudes. The effect varies greatly over the globe, but some published estimates of the global average value are:
• 5.3% (9 W/m²) over 1958-85 (Stanhill and Moreshet, 1992)
• 2%/decade over 1964–93 (Gilgen et al, 1998)
• 2.7%/decade (total 20 W/m²) up to 2000 (Stanhill and Cohen, 2001)
• 4% over 1961-1990 (Liepert 2002)51
Further studies are seeking to measure and predict this "global dimming" more accurately. We will not include this effect in this comparison, although it would likely increase GSO’s advantage – highlighting the vagaries of being below the earth’s increasingly burdened
atmosphere.52 Variations due to “global dimming" have not yet been understood well enough to be placed into the Air Mass specifications.
We should also note that forty to fifty percent of Space Power satellite output is expected to be lost during the end-to-end wireless power transmission (WPT) process through the atmosphere; that is moving the power from the space PV output to your electric power grid input. See that chapter for further details.
So if we had a PV array on earth that collected 1000. kWatt hours per year, we would expect that array to collect about 10,000. kWatt hours per year if it was orbiting at GSO.
Regardless of these asides, we are quite close to a 10 to 1 PV power advantage for GSO over terrestrial PV, specifically the US, European, Japanese or similar mid-latitudes, for a PV collector of given efficiency averaged over its daily or annual operation.
~~~~
This was excerpted from the Photovoltaics chapter at the SSPW
http://www.sspi.gatech.edu/photovoltaics2006.pdf
Sun and revenue are not the same; from your link:
"We should also note that forty to fifty percent of Space Power satellite output is expected to be lost during the end-to-end wireless power transmission (WPT) process through the atmosphere; that is moving the power from the space PV output to your electric power grid input."
The theoretical generation of space-based cells vs. the observed generation of ground-based cells is thus at most 5:1.
There is no reason not to site ground-based cells in favourable locations, however, thanks to the ability of HVDC lines to efficiently carry power long distances. In particular, one would expect systems to be installed in locations with high average irradiance and low smog and haze (likely by being further away from population centres than the study referenced, which does not appear to be available online).
A more appropriate comparison for the US would be somewhere around Pheonix, AZ (irradiance 6.5). With that location, the ratio is 3.7:1; assuming a comparable part of that sparsely-populated state can be used that's not close to smog from population centres, the ratio will improve, up to 2.6:1.
Given that data, and taking into account HVDC transmission losses, a reasonable factor to use is probably 3.5:1 for delivered power from a space-based vs. ground-based solar panel.
"A 2007 NASA sponsored satellite-based study sheds light on the puzzling observations by other scientists that the amount of sunlight reaching Earth's surface had been steadily declining in recent decades, suddenly started to rebound around 1990. This switch from a "global dimming" trend to a "brightening" trend happened just as global aerosol levels started to decline.[30][35]"
An apples to apples comparison is to look at the output from a PV panel on earth or at GSO. This is what the article does, Pitt. This PV is observed output in space not merely theoretical, as you guess. The amorphous silicon we refer to has flown on both MIR and the ISS. The amorphous silicon on the space panels had longer life than the PV on Earth because at these higher temperatures it was continuously reannealing - this is detailed at the referenced chapter.
If you really want to look beyond the panel output contacts, you will find a serious design review favors SSP even more because the GSO location provides free high vacuum and free very low temperatures. This means we can run superconducting (HTSC) cabling that has lower losses than earth-side cabling and does not require active refrigeration, (including your HVDC), which is required to operate HTSC on Earth. All that is required to keep these liquid nitrogen temps at GSO is to stay in shadow, which is simple and cheap. Superconducting cabling can put a hundred times as much current through a regular conductor of the same cross section size, so it is far lighter to ship.
The point to focus on is EROEI (Energy Return on Energy Invested)- we get 9.6 times as much energy output from the same panel at GSO compared to the one on Earth.
This is an insurmountable advantage for SSP. It is even greater when you attempt to do an apples to apples comparison providing baseload power on Earth through storage batteries, without hiding behind coal plants. SSP is naturally baseload - no storage needed. You won't power Chicago on batteries charged from PV - even PV in Phoenix.
Exactly because costs in space do normally not matter.
Having tons of batteries in space is costly.
Regardless of the fact that energy input per Watt is more important than efficiency per area because there is NO LACK OF ROOF and sunny desert area on earth (so, who cares about Wh per area):
Even if that was achievable. You will never receive 9.6 times more energy than with conventional roof-PV available now. Since you still need to transmit DC power to the microwave converter in space (loss 1), convert DC power in space to microwave power in space (loss 2), transmit microwave power over a distance of 35,800 km (loss 3) convert it back from microwave power to AC-Power (loss 4) on earth and distribute it over thousands of kms (loss 5) over thousands of transformer (loss 6).
Since total_loss=loss_1*loss_2*loss_3*loss_4*loss_5*loss_6 you'll most probably lose more than 50%.
Whereas the solar power generated on a roof can almost directly be consumed underneath that roof or stored as heat energy using a heat pump already available now.
You also need to deduct the energy costs of these 5megawatt lasers that are pushing the work-trucks around, too.
That 'severe' challenge of storage for Terran-AltEnergy has countless solutions, large and small. I was thinking about just getting a big pressure tank to hold for my fridge and freezer some spare (2-3 weeks worth) coolant. Think what big grocers could do with their wide rooftops and some basement tank space.. (and I still got to work the word Space into it)
Right out of the article:
"The model accounts for power satellites not sold but diverted internally to make Skylon propellants and to power the lasers."
You missed it.
Exactly correct, anyone!
Note also that that 70% of the energy used in the home is heat energy, not electric energy. Doing solar combined with ground coupled heat pump essentially puts the energy where it is needed when it is needed with far less in distribution losses in general.
For electric energy, think of the businesses and facilities that only need any real volume of energy in the daytime anyway (schools, post offices, shopping malls, office parks, law firms, banks,etc., the list is very long)...and you will be amazed at this fascination with "24 hour power production"...we are already up to our ears in excess night time electric power now! As the cost of PV solar drops, we will be easily able to produce more than enough electric power. The issue is the buildout time, and on that the space based method has it's only real advantage, because it is a centralized system. Otherwise, no advantage, and more liabilities than it's worth.
RC
Space solar, however, is 9.6 times efficient than putting PV panels on your roof.
Bull.
I have solar PV today. PV in space has gotten me exactly 0 watts.
0 times anything is 0.
The energy return on energy invested is higher for SSP than any other energy alternative we know of
Again Bull. You THINK the return is going to be better.
The JPL Goldstone microwave wireless power transfer demonstration recorded 84 % efficiency in 1975. 30 kW was successfully transferred from the transmitting large parabolic antenna dish to the distant rectenna site over a distance of 1.6 km.
So? 1.6 km is not 'an outerspace' distance. Do you have a point you want to make here?
The *KEY* point refuting your own claim is this:
the low efficiency makes it uneconomic.
The energy density on earth via SSP microwaves is on par with photons that the Earth now gets per http://www.ursi.org/WP/WP-SPS%20final.htm All that work for about 2x more energy.
(Note also how I at least use links to back my position. Your SSP position is yet more handwaving)
Gail,
Your statement:
"Additionally, maintaining wind turbines and building new wind turbines will be very difficult, if the amount of fossil fuel decreases greatly, because of the need to maintain roads and other infrastructure in order to keep servicing the wind turbines."
cannot be correct, because even erecting new turbines only uses 5% of the energy used in turbine construction, and this amount of energy is returned in the first 2 days of operation. A 1.5 MW turbine has 250 tonnes plus 250 tonnes of concrete in foundations.If you had to move all of that 200kms, thats 100,000tonne/kms, at one gallon diesel or 10kWh electricity per 40tonnes/km so a total of 25,000 kwh( a 1.5 MWh turbine will produce 500kW) so 50 hours operation will generate 25MWh.
Surely maintenance will be less than this, you could ship the entire turbine(100 tonnes) back to the factory once a year and not notice the energy used.
These turbines can be moved over dirt roads, what sort of road maintenance is required? What sort of energy to grade 2 km road/once a month/ per turbine?
A couple of questions:
- Your cost of 2cents per kilowatt is just capital replacement, correct? No O&M, no financing needs? It would be great to assume the first satellites we put up would work like the Hubble did, I mean, not like the Hubble...
- What are your assumptions for rocket fuel cost? If there is little use of fossil fuels by 2040, does that mean the price is exponential until then? You can't power satellites into orbit with satellite energy until enough of them are up there. Sustainable energy isn't really sustainable until you can use it to perpetuate itself.
- So the satellites are in Geosynchronous orbit, yet they see 24 hours of sun? Am I missing something?
"Your cost of 2 cents per kilowatt is just capital replacement, correct? No O&M, no financing needs?"
The model for the construction company includes interest. The power companies who by them can finance them for 30 years and get return of capital in 10. That's about the same financial model as Three Gorges Dam I have not included operations and maintenance because there is no reason the first should be significant and it's really hard to figure out what (beside rarely being damaged by meteors) is going to need fixing. Re Hubble's woes, people will be on orbit to fix what goes wrong and the parts pipeline is only 15 hours.
The project requires initial power for the lasers and hydrogen/oxygen to fuel the Skylons. But the model devotes about one part in eight of the power satellites to running the lasers and making hydrogen from water for the Skylons. The lasers are off the grid in about a year.
And you are correct about sustainable energy. The remarkable thing about power satellites is how fast they pay back the lift energy--a few months even for pure rockets.
"So the satellites are in Geosynchronous orbit, yet they see 24 hours of sun? Am I missing something?"
They go into the earth's shadow peaking at 70 minutes a day around the spring and fall equinoxes for a few weeks. Otherwise they are in the sun all the time, just like the communication satellites. It's a geometry problem where GEO is tilted 23 degrees from the sun.
The biggest hurdle to starting this project will be financing. With something as novel as space solar, your financiers will want a much higher reward for such high risk (at least at the outset) and that reward will manifest itself in the form of higher rate of return. Comparison to Three Gorges probably does a disservice to the type of proposed project.
With the financial markets in the state that they're in, financing is almost an impossibility at the moment unless you have cash. I work for a solar startup, and the financial collapse was a game-changer for many solar companies. No one is going to want to up-front a couple billion dollars on a highly risky enterprise because no one is willing to risk that kind of money right now. Is SSP feasible at 15% interest? 20%? 30%? Because that's probably what I'd want to be paid for sending untested power plants into orbit.
Will this economic climate abate, probably. How long until cheaper credit is available, nobody knows, and maybe it will never come back. The problem is never the technology in the long run, it's all about how good it can be right now, and right now SSP is a big fat zero in the eyes of the people with the moola.
Don't get me wrong, I love space. I planned on becoming an Aerospace engineer until a JPL'er told me to not waste my time because we won't have enough gas to drive our cars, much less launch rockets (which led me to LATOC and then here). But now I'm a Sys. Eng and working on getting renewable solutions done here on Earth because we still have a ways to go before we exhaust those possibilities.
"So the satellites are in Geosynchronous orbit, yet they see 24 hours of sun? Am I missing something?"
They go into the earth's shadow peaking at 70 minutes a day around the spring and fall equinoxes for a few weeks. Otherwise they are in the sun all the time, just like the communication satellites. It's a geometry problem where GEO is tilted 23 degrees from the sun.
Also even in 'Earths Shadow' for 70 minutes the satelites would still be getting 90% of maximum sunlight (WAG) because the sun is 800,000 miles and Earth is 8000 miles. Do the geometry and figure out the percentage blocked by the relatively tiny Earth...
I would post a hand drawn picture to explain if I knew how.
IF the satelites were at 200 or 500 miles from Earth the sunlight would be blocked for at least 25% of the time, but GEO is at 24,000 miles; the original post has a picture that is to scale.
I understand the time obscured now.
" Do the geometry and figure out the percentage blocked by the relatively tiny Earth..."
You dared me: At 24,000 miles, the earth is 36.5 degrees of the satellite's view. At 94.42 million miles, the sun is 1.05 degrees of the satellite's view. That means for the majority of the 70 minutes traversal, the satellite sees 0% of the incident insolation. The earth's shadow is not the size of a satellite even at the distance of the moon (hence, lunar eclipses and similarly solar eclipses).
Actually from GEO the Earth is 17.4 degrees in diameter and the sun is about 0.5 degrees in diameter (the same as from the ground).
Draw with paint.net or the like, save file, host at ImageShack or some other file hosting service.
Approach #2: Draw in paint program or create chart in OpenOffice/MS Office/etc.,
take a screenshot (Print Screen button on Windows keyboard, above Delete and Insert), paste results into image editor like IrfanView, save, host at IS.
TOD should have an intro primer explaining things like this. Visuals can really kick things along in discussions such as this.
What?! they were out of burritos!
Your guide works great! I was skeptical at first, but I think that sketch represents my thoughts far better than any written argument I could have made.
Crazy Eddie!
I love space stuff. Cut my teeth on it, am spiritually drawn to it. Have spent time publicly advocating it over the decades. Met with von Braun and O' Neill and supported them. Spent all my money to make it down to see the last Saturn V lift off. Have had a number of astronauts involved in my non-space-related projects. Last time I went to the mainland I stayed at Nasa Ames to meet with space folks. I still feel the same way I did when I was a kid.
That said, I must reluctantly comment that "engineering only" solutions to our current pickle - human overshoot - seem to take the form of presenting the set of things that are not obviously physically impossible. In a delusional culture - and we certainly have one - that's a valuable service.
Unfortunately, the information is rarely sorted much finer than that, and indeed one often sees "that which is not physically impossible" conflated with "that which will work", as I think is the case here.
Indeed, when figuring what MIGHT work, there's reductionist analysis of component parts of a system, and then there's analysis which includes path dependency, real-world context, and intermediate states. Generally in idealized engineering solutions, there's a long series of things which have to go exactly right, without hiatus or debugging. The current crop of human experts tends to minimize the importance of the latter, to our detriment.
It would be cruel to vivisect this particular proposal by "will it work" criteria, since it's well-meaning and is valuable in pointing out some nice tech stuff, which is entertaining to read in its own right. Suffice to say, it'll never happen.
"Generally in idealized engineering solutions, there's a long series of things which have to go exactly right, without hiatus or debugging. The current crop of human experts tends to minimize the importance of the latter, to our detriment."
The analogy for this project (if it is to be done at all) is the Manhattan Project. From the first there were two paths to fissionable materials, sorting out U235 and making plutonium. There were three or four ways to sort out U235. They tried them all, they all worked, some a good deal better than others.
There are at least two ways to do every major development in this project. Fiber lasers are up to a kW per fiber. Alkali metal vapor is the alternative for MW scale lasers. Both would be pumped with semiconductor lasers which are not in question since they are made in large sizes and numbers now. Both routes should be explored until it is obvious that one is much better than the other.
While Skylon with SABRE engines looks really good, any single stage to very low earth orbit is good enough since lasers will rapidly pump the second stage to GEO.
"Suffice to say, it'll never happen."
Probably not if the US was the only player.
"Und I’m learning Chinese!" says Wernher von Braun.
Hi Keith,
On TOD, most of us try to be polite and I appreciate that very much. I was always amused when I worked in India how the Prime Minister (I think the top guy was called that) would go on radio to take questions from average citizens. Nearly every caller would spend a couple of minutes praising the PM and then proceed to rip him a new bodily orfice.
Why do you use your talent (you are obviously a very bright guy) to divert us from the obvious problem - that there are too many humans? So what if you could deliver more energy from space - is that a good thing? What is the total impact on the ecosphere to have more humans even if more electricy is available? I suppose you could argue about a bridge technology, but what about the obvious fact that Peak Oil is imminent and your concepts are not?
At the end of the day, your vision is a very fragile one that could lead to an even more catestrophic collapse if it was actually supported and funded. I can only hope that folks of your intellectual capacity might one day turn your prowess on the real needs of humanity and the planet at large.
"talent ... to divert us from the obvious problem - that there are too many humans?"
The problem is not too many humans, it is too many humans for the technology level we are at.
Would you be concerned about a population of a trillion if all but a billion of them were living off earth?
"total impact on the ecosphere to have more humans even if more electricy is available?"
We could quit burning coal and oil. Does that seem like a good idea to you?
"turn your prowess on the real needs of humanity and the planet at large."
What are the "real needs"? Some people seem to need a Hummer.
I've been aware of Skylon for many years and I've actually talked to Alan Bond about it. In my opinion it is just on the edge of what is technically feasible. The main problem is that it depends on both a new airframe and a new engine (SABRE). I would give both the airframe and engine only a 10% chance of being completed to specification by any one design team (that is not to say that another design team might not complete them to spec, but that any single seemingly competent design team has only a 10% chance of completing them within the mass budget, at the performance required, and without going many times over budget). Alan Bond I believe recognises this and wants a series of risk reduction exercises first, mock-ups, wind tunnel tests, prototypes of various components etc. Most of this could be done reasonably cheaply, but would take time. That is one reason why a timescale of 5 years is totally unrealistic. Another is that there would have to be a long flight test period (probably a couple of years) to certify such an unusual aircraft. Without the risk reduction there is only a 1% chance of both the airframe and engine working to specification, even with an advanced technology risk reduction exercise in my opinion there is still only a 10-20% chance of it being completed by any one design team.
Similarly there are the lasers, mirrors and laser powered upper stage, none of these have been demonstrated. I would give them only a 60% chance of working.
The nearly single stage to orbit use of the Skylon in order to boost its payload to GEO to 25 tonnes is unproven, as it would mean the Skylon was performing sub-orbital hops it would likely lead to operational problems as the Skylon would not land at the spaceport it left from. On that note, there is one equatorial spaceport at present, adding a few more would be costly.
High powered laser beams targeting arbitrary spacecraft are a dual use technology, the US government would not want that capability in the hands of anyone else but themselves.
Accommodation for 1000 in GEO is going to be difficult to achieve. It is recognised among spaceflight visionaries that using 20 tonne modules docked together (no construction), just about anything can be built in space. Construction (that is anything that involves space walks or robotic assembly), it very costly and time-consuming. Space walks are very tiring and use lots of resources, the current generation of space suits have limited lifetimes and are very expensive. Building something 100x the size of the ISS at GEO without the support of the space shuttle or equivalent is going to be very, very expensive if only 6 tonnes at a time are available. For example, just one aspect is lifeboats, the only craft capable would be Orion, an Orion command module and long life service module would I guess cost $20-50M, when purchased in bulk and would last maybe 5-10 years in orbit. They carry 7 astronauts so about 140 would be needed for a cost of $280-1400M/year. I don't think they would fit in Skylon so launch costs would be an order of magnitude larger.
I also think that 1000 people at GEO would be hard pushed to construct a 1GW power sat in less than a month, these are big, big structures. Just moving an element into position could take hours. The Skylon payload bay is small (very small in comparison to a power sat) and so a large number of components will be needed (even if some can be folded), size limitations are probably going to be more difficult to design round rather than mass limitations.
If there are 100 flights per day and a Skylon lasts 500 flights then a replacement is needed every 5 days, I can't reconcile that with a production rate of 5 per quarter.
I agree with others that financing is going to be the most difficult aspect, I think you are looking at a up-front development cost of several $100B before the first power sat is constructed, if only one per month can be constructed due to manpower limitations in GEO then just then they will have to cost several billion dollars (perhaps $5-10B) just to cover the debt repayments. That would make the electricity no cheaper than Earth-based renewables.
This brings up the point that power sat construction with this scheme only makes sense if large numbers are produced, this means the planning from the start is on a grand scale. Production of hundreds of 747 size Skylons, massive structures in space 2-3 orders of magnitude bugger than anything before, vast commitments of cash and highly skilled manpower. There is no dipping our toes in the water first, this is a head-first plunge, lets just hope the water is not 3cm deep.
Ah, much meat here, excellent.
"That is one reason why a timescale of 5 years is totally unrealistic"
Amazing things can happen with a ton of money. Think Manhattan project, three years. And if it is done at all, chances are it will not be run from the western world. Consider this replaces coal and the Chinese admit they kill 6,000 a year mining coal. Point re multiple design teams is a good one.
"there are the lasers, mirrors and laser powered upper stage"
If we go with ablation, the upper stage propulstion is dead simple, a solid block, no pumps or anything.
There are multiple ways to get to MW lasers, at least one of them should work. The mirrors in GEO are harder and I freely admit I don't understand them.
"High powered laser beams targeting arbitrary spacecraft are a dual use technology, the US government would not want that capability in the hands of anyone else but themselves."
You put your finger on what might be the biggest problem.
There are only a few good places to launch the booster stage (lots of water to the east). The lasers have to be ~45 degrees of longitude to the west to get the acceleration geometry to work out. The best pairs are Brazil with the lasers in south Texas or Mexico, Somalia with the lasers in Spain, and the east end of Indonesia with the lasers in China or India. For the first set, ground targets in the Western hemisphere could be hit. For the second, Europe, Africa and the mid east. For the last set, China and India. Google Earth is essential to visualize this.
I don't know if China or India would go to war to stop a laser installation in the other country, but both are nuclear powers. A 4 GW beam has the energy of a ton of TNT per second. Maybe they would rather install the lasers in Texas with the US having turn off authority to prevent it being a target.
Of course, anything in space can be clobbered, but that's not much different from now.
"I also think that 1000 people at GEO would be hard pushed to construct a 1GW power sat in less than a month,"
I gave a lot of thought to this in the context of a novel I was working on. Have you ever seen on of those gutter making machines? They run a roll of metal through a former and get on-the-spot gutters. The structure can be built out of beams shipped up as rolls of near foil thickness and pulled though beam formers.
What I think would be essential for rapid production is a jig or dry dock to build them in.
It may be necessary to stretch the beams a tiny bit in order to get them straight. It's possibly worth building a really long heavy duty tether to get the force to stretch the original beams for the dry dock. The dry dock can stretch production beams.
"100 flights per day and a Skylon lasts 500 flights then a replacement is needed every 5 days, I can't reconcile that with a production rate of 5 per quarter."
If you go into the spread sheet where there are 102 flights per day, the scrap is 18 and the fleet grows by two for a production rate of 20/quarter. That's 2 in 9 days which is close enough. It takes 14 years to reach this production rate, which is still lower than Boeing's peak 747 production.
"I think you are looking at a up-front development cost of several $100B before the first power sat is constructed"
If that's the case, then this just isn't going to happen.
"This brings up the point that power sat construction with this scheme only makes sense if large numbers are produced, this means the planning from the start is on a grand scale. Production of hundreds of 747 size Skylons, massive structures in space 2-3 orders of magnitude bugger than anything before, vast commitments of cash and highly skilled manpower. There is no dipping our toes in the water first, this is a head-first plunge, lets just hope the water is not 3cm deep."
If you want to solve the energy/carbon problems you have to think on this scale.
The group that does it (if it is done at all) will be controlling more energy than the entire production of oil, gas and coal.
To simplify the model, I had the power sats sold as soon as produced. But there is no reason they could not sell energy instead.
Keith,
You're using lasers to push spacecraft into orbit, then converting sunlight to electricity and beaming it back to earth (correct me if I have misunderstood).
I'm concerned about the effects on the atmosphere, specifically the protective ozone layer.
1. You're proposing building a bunch of Skylons each of which will be making hundreds of trips. It's well known that jets flying in the lower stratosphere destroy the ozone, but Skylons will be flying right through it on a regular basis using air-breathing engines (a type of jet turbine, I assume). Releasing NOx into the stratosphere destroys ozone, so has this been taken into account?
2. You're punching lasers back and forth to boost the Skylons and receive the power back on Earth. What effect does this have on the atmosphere in general and the ozone specifically?
On a related note, what is the effect around the area of the receiving stations of increased radiation being beamed to it?
I'm imagining the environmental impact studies on this will take a decade...
Re: Skylons with the SAbre engine
http://www.reactionengines.co.uk/sabre.html
these use liquid hydrogen and oxygen and would be cleaner than most existing rockets or airplanes. Since we put millions of jet airplanes up each year, 1 million here in Atlanta alone - the addition of a few thousand Skylons/sabres or other rockets would appear to be invisible from an environmental perspective.
Re: lasers - Since the goal is to not be blocked by clouds, this scheme would work hard to minimize loss via atmospheric interference which is a significant concern.
The SABRE engine uses liquid hydrogen only in the second (rocket) phase - at altitudes of 26km and at Mach 5.5.
Adding several hundred of those high-powered space crafts flying straight through the stratosphere would probably have an immediate and significant impact on the ozone layer.
Actually Not -as you know the rocket's LOX and LOH yield water which does not damage ozone. You are confusing this with Chlorofluorocarbons (CFCs).
http://www.theozonehole.com/cfc.htm
You will also be happy to know that excellent progress is being made on an even cleaner boost to orbit - an electromagnetic first stage. The Navy's next generation aircraft carrier launch system, EMALS, will be electromagnetic, which is now being installed for test in New Jersey -
http://www.theengineer.co.uk/Articles/311592/Magnetic+force.htm
http://www.app.com/article/20090612/NEWS/906120366/1070/NEWS02
It will be both more powerful and more controllable so it can handle both heavier jets and lighter more delicate ones.
Not to mention EROEI.
How many powersats will be required just to power the lasers?
"How many powersats will be required just to power the lasers?"
When it has reached initial design capacity, making about 200 GW of power sats a year, the GW produced to date is 637.2. Of that 18.4 GW is dedicated to making Skylon fuel, and 17.6 to powering the lasers. That's about 5.6%.
Oh, and I think your launch costs are at least a factor of 3 too low. You have only included the Skylon depreciation, there are also operations and the cost of the upper stage. $150/kg to GEO would still be incredibly good, most of the recent launcher ideas I've seen struggle to make $100/kg to LEO at high flight rates (equivalent to > $300/kg to GEO).
Hello TODers,
I don't have the eng. expertise to dispute this keypost, so I will merely offer this cautionary note:
http://energybulletin.net/node/49230
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What if the [techno-optimists and cornucopians=TOCs] are half right?
by Kurt Cobb
[Last Paragraph]..That points us to the biggest danger of all: It's not that the TOCs are dead wrong, something I believe might actually be clear to nearly every thinking person if it were true. Rather, the biggest danger is that the TOCs are half right and that their endless parade of techno-fixes will prevent resources from flowing to other endeavors which are much more likely to produce a sustainable world in the long run.
----------------------
If these 'space funds' were instead first devoted to Peak Outreach, abolishing outside lighting and signage, full-on O-NPK recycling, minimal water usage strategies, maximum reduction in specie extinction rates, relocalized permaculture,and SpiderWebRiding: the energy saved might then allow some building of space-based power generation. If we are now postPeak: shouldn't we worry later about regaining "The Days of Future Passed"?
My broad boundary analysis guess is the USA's 16,000 golf courses and countless industrial carwash/detail extravaganzas alone burn more energy and resources than 10 NASAs.
Remember, we are evolved to do darkness, not starvation: thus, it would seem that first efforts should go towards this proposed end. Only then should we try for the later goal of achieving our endless fascination, with having countless outside lights burning all night trying to get photons to reflect back from black asphalt:
http://www.nightskynation.com/pics/earth-at-night.jpg
------------
"Nights in White Satin, never reaching the End.."
-------------
This is what it should look like:
http://www.nasa.gov/images/content/208416main_earth_at_night.jpg
---------------
Nights in Black Satin, Always reaching an end.
---------------
"Beauty I've always missed
With these eyes before
Just what the truth is
I can't say anymore..
..but we decide which is real, or which is illusion."
Bob Shaw in Phx,Az Are Humans Smarter than Yeast?
Of course, my apologies to The Moody Blues.
If you want an alternative energy scheme: how about we save the multiple species of bats, cats, whales, and dolphins from extinction? I think it would be pretty cool to adopt these species' very,very hi-tech, then echo-locate and freely navigate in the nightly darkness, or have my eyes dilate sufficiently like the cats to peer through the darkness:
http://media.photobucket.com/image/jaguar%20at%20night/darkguyver718/8d9...
--------------------
Black Jaguar Stalks Night
--------------------
The opportunity cost from this scheme is very high. Up front there are hundreds of billions of dollars, large commitments of labour and technical resources, all of which might be for nothing if there are insurmountable technical or financial problems. Just the manufacturing resources to make 100 upper stages per day and a Skylon every 5 days are considerable.
Start-up costs for this project would be larger than R&D on all renewables + nuclear fission and fusion put together. We would risk draining the R&D effort on every other power source, partly because there would not be enough money for both, partly because investment in something that costs $0.05/kW does not look too sensible if someone is promising $0.02/kW.
Hello Mike Atkinson,
Thxs for your reply. I like how the darkened Earth image is doing the Flehman Response [picture the 'Smiley Face' emoticon with eyes closed, such as this )]:
http://en.wikipedia.org/wiki/Flehmen
This is, of course, a common, evolved response to those practicing the Yeasty Peakoil Shoutout, as the inhaled aroma, including [S]ulphur, sets off '[S]ynaptic wildfire[S]'. IMO, periodic reloading can further enhance real-time recognition and mental re-wiring. YMMV, but consider the possible equivalence of Flehman = Fleischman's Yeast.
Again, I am not an expert in these matters, but it seems logical that our tendency to smile is a long evolved Flehman response plus the inclusion of other evolved factors:
http://www.youtube.com/watch?v=dw-u5wazi_w
--------------
Wildfire Reloaded [4:52]
--------------
http://en.wikipedia.org/wiki/Methanethiol
----------------
..An odor threshold of 0.002 ppm has been reported.
----------------
IMO, many people underestimate that "She came down from Yellow Mountain..."
http://en.wikipedia.org/wiki/Sulfur
---------------------
Biological role
Main article: Sulfur assimilation
See sulfur cycle for more on the inorganic and organic natural transformations of sulfur.
Sulfur is an essential component of all living cells...
--------------------
Recall that P is #1, S is #2 on the Bio-Elemental intensity list of Asimov's.
There are certainly much better uses of the energy required to lift a factory with 1000 employees as well as living space and other services out of the gravity well that is over 22,000 miles deep. What about a spread sheet giving the gigajoules needed instead of the dollars needed. To begin with if we wanted base load solar power there is OTEC or just simply thermally charging a large container of gravel using CSP. Then there is the possibility of high altitude balloons covered in thin film PV. Cloud tops rarely exceed 10 miles meaning power would be generated over 4300 hours per year (50% capacity factor). Cloudy days may even provide more power since light reflected by the clouds would be available to PV cells on the balloon bottoms. Aluminum cables wrapped in carbon fiber and mylar would carry power to the ground much more efficiently than microwaves.
Can you say how big the mirrors are? I would guess in the 1m diameter range.
A crew of 1000 on a six month on six month off rotation would require 2 Orion class ships arriving and leaving each day. Current cost in the $10's of billions each year. While there are ways of reducing that recurring cost, they all would require even more up-front costs.
"Can you say how big the mirrors are?"
It's somewhere in Jordin Kare's papers. My memory is 30 meters. If we are using ablation, they have to be big and a lot of them. Otherwise the *mirrors* ablate.
"would require 2 Orion class ships . . . each day."
Some of the development money is for a passenger module for the Skylon. With a modest block of reaction mass it gets to GEO. The problem is not getting workers to GEO and it's not supplying them (ten tons a day out of 2400). The problem is getting them back down. In a mature system we could do the reverse, Hohmann transfer orbit and capture into LEO with laser propulsion, then load the module up in a Skylon in LEO. It's harder till a lot of laser power is built up.
Maybe it would be easier to ship up families and leave them there for years.
Calling it a module doesn't mean it is not an Orion class space ship. It will have to have similar size, mass and endurance for safety reasons.
Your whole scheme depends on laser ablation propulsion, I'm not aware of any medium scale high delta v demonstrations. I remember a small scale low delta v demonstration about 10 years ago, but I haven't seen anything since. Have there been any scaled up demonstrations, and if not why do you think it will work (small scale solid rockets are easy, large scale ones are very difficult to design, build and test - won't ablative rockets be similarly difficult).
"Calling it a module doesn't mean . . ."
I agree. The cost for a 30 passenger module was upwards of $3 B.
"Your whole scheme depends on laser ablation propulsion,"
Actually no. It depends on high exhaust velocity and relatively high thrust, between a g and a g and a half. I don't care how we get it, heating hydrogen would be fine. Laser ablation is rather simple and there is always something to be said for simple.
"scaled up demonstrations"
No, for the simple reason lasers of this power class are just becoming possible.
"small scale solid rockets are easy, large scale ones are very difficult to design, build and test - won't ablative rockets be similarly difficult)."
Possibly, but we don't think so. The reason is that ablation takes place as a surface effect. So other than having to scale the laser into the GW range, big ones and small ones are about the same. Now getting a bank of 1000 MW class lasers to act as one GW class laser, that might be hard. But it's a timing problem and electronics has gotten really good at such problems.
Besides the fact that solar power can be harvested on earth (Solar hot water heating/cooling, Wind, Hydro, Photovoltaics, CSP, Wave, Biomass etc.)
What's the conversion efficiency from DC Photovoltaic power to Microwave power?
This link claims 64% conversion efficiency for a microwave oven: http://www.spiritus-temporis.com/microwave-oven/efficiency.html
But, assuming 1 GW can be converted at an efficiency of 90%, that would mean 100 MW needs to constantly be disposed of.
How does one dispose of 100 MW heat energy at reasonable temperatures without any fluid (atmosphere, rivers etc.) available for heat transfer?
A beautiful question there at the end. Well done.
Radiators on the shaded side of the power sat. It is well known technology, just needs to be scaled up a factor of 10,000 for a power sat!
Some discussion in the earlier posts were about Space Based Solar Power (SBSP) which used mild concentration, perhaps 5 or 6 to 1. With those, the PV area involved becomes less and the effective radiating power is also reduced if passive radiators are used. I think that's what Solaren is planning to do, judging from their patent. While some of the sunlight is converted to electricity, the rest must be radiated away to cool the PV cells. For such a large area as proposed, the cooling must be passive, not active, especially given the maintenance constraints. As a result, the temperature at the PV cells might be rather high, on the order of 250C, which would result in reduced efficiency of cells made of silicon. Just another "small problem" which could kill the concept, IMHO...
E. Swanson
Increasing the PV cell temperature to 250C would almost certainly reduce their life. PV cells for satellites do not have radiators, I don't see why they would be needed on a SPS unless they were heated by concentration. Satellites don't use concentration and given their mass constraints, if concentration were beneficial I think they would use it.
Boeing uses solar concentrators on some of its 702 series satellites (see http://www.boeing.com/defense-space/space/bss/factsheets/702/anik_f1/ani... for example).
I don't know why they're not more common but it could be a combination of Boeing holding the patents, cell life at the higher temperatures or just the increased power not being worth the increased complexity.
There was a mention of steam turbines upthread, I think the heat rejection problem in the vacuum of space would be show stopper for them.
The problem with that scheme is that many very expensive lasers must be in place before the first launch
I'd say the bigger problem is overcoming valid concerns like answering "Why Bother when present PV Cells can do the job"
http://www.ursi.org/WP/WP-SPS%20final.htm
The black dots are what would be needed (yes, this puts 'em in the ecologically sensitive desert)
http://upload.wikimedia.org/wikipedia/commons/thumb/d/db/Solar_land_area...
(edit: Note how the SSP people don't even TRY to refute the solar PV land area or the URSI White Paper on Solar Power Satellite (SPS) Systems.)
For the people who did not follow the link:
Why is this a stupid idea?
Sigh.
Let me count the ways...
Actually, - naaah. Others with greater acumen in that department have smacked down the science and feasibility of this idea a whole bunchy boatload of times. I need not pile on.
What I will add is this:
You can spend say, $(X) dollars to put one of these stupid things in the sky, and I can guarantee you that some country you don't like will spend $(X/100) on a missile to blast the thing to flinders. Ad then you'd be out $X AND you'd be shivering in the dark, while you enemy laughs at the pitiful hobbled giant.
Brilliant move there, ace. Let me know how it works out for ya.
"You can spend say, $(X) dollars to put one of these stupid things in the sky, and I can guarantee you that some country you don't like will spend $(X/100) on a missile to blast the thing to flinders. Ad then you'd be out $X AND you'd be shivering in the dark, while you enemy laughs at the pitiful hobbled giant."
Let's think about this. Nothing short of a nuke would take out a power sat. Geosynchronous orbit is a long way out. Efficient orbits take 5 hours, very fast orbits would take at least an hour. Whoever is building these things has a GW scale ablation propulsion laser. This class of lasers burns off tens of kg of material from the surface of anything per second. The missile isn't going to get there.
If any get built at all, these things are going to be owned by all the major countries--and there are going to be thousands of them.
But just say someone constructed a really expensive rocket plus nuke, launched and took out a Chinese power sat. Obviously a spare one gets switched on. And now they have to cope with a bunch of really pissed Chinese. Not the best idea I can think of.
If the people controlling the launch lasers became disaffected with those in the power stations or vice versa, it could make for some interesting death-beam battles.
Indeed, anyone with lasers that powerful and flawlessly accurate, plus a few orbiting mirrors, could just conquer the world... a point presumably not lost on those NOT building one.
But on a more prosaic level, lawsuits alone would probably prevent such a thing from being deployed by the USA. And the USA would not countenance the building of such a system by anyone else. China? right. Not that China would be silly enough.
Other nations will presumably take some sort of umbrage at the owner of the system having not one but two sorts of radiation weapons, even if you don't count the ability to drop large spare masses on people through the gravity well.
If someone wanted to nuke the things, it could be done stealthily rather than a direct ballistic shot from a declared opponent. And there would be interesting challenges to EMP-harden a thing that size. Not to mention the rectenna receiver.
And the answer, if such an attack succeeds, is to "turn on the spare one?" OK.
"But on a more prosaic level, lawsuits alone would probably prevent such a thing from being deployed by the USA."
I agree, which is why I don't think it will be done in the US.
"And the USA would not countenance the building of such a system by anyone else. China? right."
If China announced the were going to solve their energy and carbon problem by building power satellites using laser propulsion, how would the US stop them? Moral sanctions aren't going to do it. Would we actually nuke China for solving their energy problems in a responsible way? How about if they said they would sell energy or power sat to anyone who wanted one?
"If someone wanted to nuke the things, it could be done stealthily rather than a direct ballistic shot from a declared opponent."
If you can think of a way, please don't keep it a secret. A rocket launch is not something you can keep from being seen. Smuggle a nuke up in the construction materials? Or a lunch pail?
"And there would be interesting challenges to EMP-harden a thing that size. Not to mention the rectenna receiver."
The power sats have to be hardened anyway to cope with solar storms. That's one reason to favor rotating machines where the conductors can be inside metal shielding.
"turn on the spare one?"
If anyone builds even a few, they build thousands of them. Spares would be maintained, not to mention that the ground grid could deal with a few missing ones.
One of the economic facts about power sats is that you build them for peak load. Why not? Other than installed hydro they are the least expensive source of power available. Instead of starting and stopping power plants, you just divert unneeded power into hydrogen production.
We've recently non-subtly threatened Iran with attack, and elements within the US were pushing for a tactical nuclear strike on Iran for building conventional fission plants. Many in Israel favor it. Japan bombed Pearl Harbor due to an oil embargo pulling the US into WWII. My comment about WWIII was not facetious. But really this is a fantasy, China is nowhere near being able to do anything remotely like this before Liebig limits take global systems down.
Smuggling nukes into space wouldn't be that hard, no. Do you think there aren't any "up there" already, piggybacked on some other launch? I'm not stating that I believe there are, but the opportunity has been there, and will remain. You're saying we'll have lasers continuously pumping out beams with the equivalent of a ton of TNT per second, and are implying my statement about getting a nuke surrepticiously into orbit is implausible? hmmm. Won't these beams potentially cut through the power stations like a sword through cheese? And with this level of launches/crashes/collissions, won't there be so much space junk that it becomes harder to detect stuff? Just asking.
Whew. So does peak load just keep going up? How many billion people do you figure on there being by the time of the singularity?
As a rhetorical device, I can see that having "spares" answers some thorny questions, but it seems to take it an additional step farther from pragmatic reality.
I've watched live TV of them trying to deploy a small solar wing on the space station. It's excruciating, doesn't always work, and is tiny, yet this is the state of the art, the real-world pinnacle of space tech for the human race at the moment. About one out of every 50 launches, the vehicle and crew are lost (which was entirely predictable) even using a "mature" technology.
If you're taking side-bets, I think Malthus is looking good.
"One of the economic facts about power sats is that you build them for peak load."
Not.
Utilities operate their power plant fleet to minimize their cost of producing power. Nuclear power plants are not the cheapest plants, but they do have the lowest marginal cost of operation. That means once you have one of these - actually either an SSP sat or a nuclear power plant - you can't afford not to run it. So it would be run baseload, just as is done now for nukes.
By the way, peaking units, such as natural gas fired turbines, have a very high marginal cost of operation so they are only run when the price of power is high enough to pay for them - when you need just one more 100 MW slice on a hot summer day and nothing else is available. Nice units like hydro have so many other restrictions such as drought control they often aren't available in hot summers, but would be turned ahead before natural gas fired turbines. The coal plants would loose running time if SSP comes on line, IMHO.
"
Think about it. At $1.6 B per GW, a power sat would be 1/3 to 1/5 of the cost for a nuclear plant, and no fuel charge at all. Even more than nuclear it is pointless to shut one off. You can sell all the power you can make at a penny a kWh to plants making dollar a gallon fuel. The hydrogen plants are smoothly controllable loads. You can turn them down to zero in hot weather.
So instead of building gas turbine units, you just put in power sats up to the peak load and use any power below peak to make hydrogen and from there, hydrocarbon fuel.
Good or bad idea, all you have to do is get financing from those who have money and love growth. Good luck.
I remember those guys. The industrial-military complex, I believe. Beats the hell out of a Mission to Mars.
As long as the US has pretensions of being a global power, we will have a space program. I'd rather see our space resources poured into this than into a manned-mission to Mars.
Whoever build power sats on the scale of thousands gets a manned mission to Mars practically for free.
Heck, they'll probably get WWIII for free before the first dozen are operational.
Keith;
Good work hanging in there, today. There were some pretty adolescent challenges put up on the board.. which do little to enhance the reputation of this site as a place where an issue should be discussed on the merits or lack of them. That stuff weakens both the potential of this site, and of the force of their arguments. Too bad.
I remain as skeptical as ever about there being a practical chance of this actually working, and the thought of those high-powered lasers and aimable GEO mirrors do truly sound like an accident or a REALLY spectacular terror-attack just waiting to happen.
I'd really like to hear about which of the various technical hurdles have actually seen real practical demonstrations yet. I'm particularly curious about the claims around Microwave Power Transmission, which seems to be confidently shrugged off every time it's asked. If it was so certain a solution, why don't we have any relevant earth-based systems established instead of this constant wrangling over stringing impossible lengths of cable across all the continents, and having to fret about replacing and maintaining such a tangle? One would think that at least a few high-power nodes would have been used for difficult runs if it was such a no-brainer.
Anyway, thanks for your thoughts today. Please do share any notes on practical demonstrations of various aspects of this that have been done, if any. (Sorry if you mentioned some above already.. I was limited to scanning this all today)
Bob Fiske
jokuhl said:
The physics and engineering of microwave transmission are well understood. The efficiency of the link depends on the diameters of the transmitter and receiver, the distance between them, and the wavelength used. For space-to-ground, the sheer size of the antennas isn't a big problem, since the transmitter is in zero-gee and the receiver is lying on its back on the ground. And you get conversion losses from electricity to microwave and back only once, at each end.
To connect points on the ground, you'd have to set the antennas on edge, and since the links are line-of-sight, you'd need yeah many in series....
What are the largest (in currentflow) practical power tests that we've undertaken at this point?
I'd think one could use a mountainside to improve the receiving area of such a setup as well, right?
I mean, being confident about the theory is great, but this is one of many completely critical lynchpins in this proposal.. so what has actually been done to demonstrate higher power Microwave Transmission, and particularly in a way that helps to assure that there are no damaging side-effects? Atmospheric, Magnetics, Unanticipated Dispersion losses..
For space-to-ground, the sheer size of the antennas isn't a big problem,
And these antennas are somehow immune to space 'debris'?
The Earth undergoes these things called 'meteor showers' - many space objects hitting the 'shield' of the atmosphere. Well known issue.
So somehow these 'not a big problem' antenna are going to avoid the known space rocks or be strong enough to withstand the bombbardment of the small rocks in space? And if one breaks up, its not going to add to the 'space junk' problem?
Perhaps you have a different view of 'big problem' - but space based transmitters being turned into debris from the passing rocks in space strike me as 'a big problem'.
Meteor strikes are not a problem. "The" transmitter is actually a collection of millions of semi-autonomous transmitting elements, operating together in a phased array. Distributed power, distributed control, no single point of failure that could take down the whole array. If one element gets taken out by a meteorite (or whatever), you'd never notice.
I don't mind challenges, even adolescent ones. Good practice and who knows, there might be a substantive objection I have not thought about.
The accident aspect is why you want the launch path over water. A boiled patch of ocean isn't a PR problem, an incinerated village is.
"Microwave Power Transmission, which seems to be confidently shrugged off every time it's asked. If it was so certain a solution, . . . One would think that at least a few high-power nodes would have been used for difficult runs if it was such a no-brainer.
Rule of thumb, it costs penny a kWh additional to ship power 1000 km on wires.
Microwave is line of sight only. There is a 50% electrical to electrical loss using microwave. That just contribute to the capital cost when the "fuel" is free, but it's a major hit when you are burning coal or uranium. To send power into space and back down again would be a 75% hit.
Even at that, the military has some projects in development for short haul microwave transmission of a few kW of power.
ps,
the 'Practically Free Manned Mission to Mars' sort of comments are maybe meant to be jocular, but they do little to inspire confidence in the pragmatism of your arguments. You might cushion such comments a bit.. I suppose it's been a long day.
Bob
No, the comment is deadly serious.
At least 90% of the cost of a Mars mission is in the cost to drag the space craft and fuel out of the earth's gravity well.
We are talking about a *200* to one reduction over the current cost of going to GEO.
Not to mention that the laser system diverted for a few days could launch a manned mars mission with a hundred people on board and get them there in weeks. Look at the Delta V slide in the article.
Heck, a few power sats at Mars and a few GW of laser power there could get them back too. Want to be able to vacation on Mars for a modest sum? Lasers able to push a 50 ton stage from sub orbital to GEO can provide a ferocious delta V.
One last plea for some 'Practicals'.
This all sounds like it fits beautifully into the Theory. How much have we done at this point to play with the Practicalities of full-size Laser-supported Propulsion? I've seen videos of lightweight laboratory tests. Do we have some experience with scaling this up to Loads that are at least one order/magn. within the intended Vehicle Weights?
Bob
'In theory, Theory should work just like the Real World.. in the Real World, the Real World doesn't seem to get the Theory.'
Hmm. Crickets..
Here is another plan to excape gravity.
Go to the South Pole.
Place a rail 1Km in Diameter on the Ice.
Make a bridge to straddle the equator of the circle.
The bridge rotates on wheels on the rail.
Water is de-airated and sprayed from the bridge.
A giant ice lense is formed. It is a mould for a reflector telescope.
Aluminum is sprayed onto the ice.
Carbon filiments are layered onto the aluminum.
A carbon framework is bonded to the lens. Piezoelectric crystals between the frame and the lens for corrections.
A second lens is created.
It is lifted with hydrogen and allowed to flip in the air.
The two lenses are joined together.
A particle accelerator is attached.
The cavity between the lenses is filled with hydrogen.
The hydrogen lifts the craft to the top of the atmosphere.
Rockets, lasers and the linear accelerator take it out to Jupiter.
It splits and each half goes to L1 and L2 respectivly.
Binocular planet finder.
How much greenhouse gases will the launch vehicles release into the atmosphere? How much of the transmitted power will be absorbed in the atmosphere and converted into heat? Just wondering.
"How much greenhouse gases will the launch vehicles release into the atmosphere?"
None. They run on hydrogen and oxygen and only make water.
"How much of the transmitted power will be absorbed in the atmosphere and converted into heat?"
Very little. You pick a frequency where not much is absorbed.
Speaking as the ultimate authority on all matters Space, I say no-can-do.
Why, you ask?
There is crap everywhere!
When these plans for powersats were formed, space was quite pristine.
The ensuing decades saw everybody and their brother shooting stuff up here like fireworks.
So it won't matter how high you position the sats above the scrum, you still have to beam your collected energy through it.
There is enough large stuff up here to increase the the chance of significant deflections into the realm of probability.
Another little fact that I've noticed of late is the heliopause is shrinking.
The amount and energy potential of the little nasties that the solar wind blocks is growing too.
Face it guys, Space ain't for Mankind.
So why don't you go home and leave it for us natives.
Tourists.
"There is crap everywhere!"
You have this right. Space junk is a really serious concern . . . till someone sets up an ablation laser.
Then they can de-orbit the lot of it. I did the calculation a while ago. It turns out that even a small test laser of 4 MW will de-orbit 800 tons a year. A mature 4 GW system could clean it all out in weeks.
It took a lot of courage to come here with your grand idea but with statements like the above it will stay firmly planted in the realm of pulp science fiction.
Just one thing, we can no longer even pour concrete roads and have them last more than a couple years, what makes you think we are capable of your somewhat more complex systems?
I drive on concrete roads in the upper Midwestern US.
They get frozen to -25F, baked to 100F, and treated with harsh anti-icing compounds and they hold up much more than 2 years with minimal maintenance.
Maybe YOU can't build a concrete road to last, but that doesn't mean nobody can.
Same conditions here.
I don't understand how you think I personally built the roads I am speaking of.
Perhaps if you were more observant you would see that assumption and the one you make about the roads in your locale are in error.
"It took a lot of courage to come here with your grand idea but with statements like the above it will stay firmly planted in the realm of pulp science fiction."
Why? I talk to real rocket scientists frequently. They don't have any problem with this statement.
Ablation lasers will ablate anything. If you hit space junk head on while it is near apogee, then it is going to slow down. (It may jink this way and that because a face at an angle to the direction of travel will produce thrust normal to the face, but on average it will slow down.)
And a laser designed to give a boost of 10k/sec to 800,000 t per year should be able to de-orbit that amount of junk in the same time. I don't have a number handy, but it would only take a month or two for a full scale propulsion laser to dispose if the space junk by slowing it down and dropping it into the atmosphere.
"Proposals have been made for ways to "sweep" space debris back into Earth's atmosphere, including automated tugs, laser brooms to vaporize or nudge particles into rapidly-decaying orbits" http://en.wikipedia.org/wiki/Space_debris#Mitigation
See also http://en.wikipedia.org/wiki/Laser_broom
I know one of the laser scientists who worked on this proposal.
"Just one thing, we can no longer even pour concrete roads and have them last more than a couple years, what makes you think we are capable of your somewhat more complex systems?"
I tend to agree with you. It's unlikely the US could do it. That doesn't mean it won't be done by someone.
I can't even begin to address the arrogance of the notion of de-orbiting any amount of space debris, regardless of size, with any possible assurance of keeping it from falling on a nonpopulated area.
How would you even begin to determine the mass and amount of energy needed to ablate any object along a predetermined path?
You should take time to recall Skylab and its tremendous failure.
Sure it was ooohs and aaahs for awhile as we watched a few lucky scientists play anti grav games but due to forces that were not completely understood, it came crashing down over a huge area avoiding a tragedy only by sheer chance.
Of course you'll say "But we learned from that".
As we did from Challenger.
And from Columbia.
And from Hubble.
And the list goes on and on.
So it would appear we really haven't learned or as the arrogance of this post suggests, choose to ignore.
Big deal.
Anymore playground boasts you want to make?
"I can't even begin to address the arrogance . . . "
My you are a friendly person.
The space junk is going to come down sooner or later--and most of it burns up rather than hitting the ground. With a little (MW scale) laser about all that makes sense is to lower the parigee till it gets to where air drag will bring it down. For a big laser (GW scale) and junk under 50 tons, it could be injected into a controlled reentry orbit.
"How would you even begin to determine the mass and amount of energy"
Mass on the large pieces is known. When a solid is ablated with a high power laser about 30% of the energy goes into Ke for the ablated material (Number from Jordin Kare). Ke =1/2 MV^2 and mv =MV will tell you how many mega watt seconds you need to affect a desired velocity change. Think about a big laser this way: One able to boost a 50 ton stage to GEO, some 10 km/sec can certainly give a few km/sec to a chunk of space junk.
Re Skylab, http://en.wikipedia.org/wiki/Skylab#Abandonment_and_reentry.
"Increased solar activity heated the outer layers of the Earth's atmosphere and thereby increased drag on Skylab, leading to an early reentry. In the previous weeks before reentry, ground controllers had re-established contact with the six year old vehicle, and were able to adjust its attitude for optimal reentry dynamics. Skylab's reentry occurred at approximately 16:37 UTC 11 July 1979. Earth reentry footprint was a narrow band (approx. 4° wide) beginning at about [show location on an interactive map] 48°S 87°E / 48°S 87°E / -48; 87 and ending at about [show location on an interactive map] 12°S 144°E / 12°S 144°E / -12; 144, an area covering portions of the Indian Ocean and Western Australia."
You can be sure that people in space will be killed and possibly some on the ground. The Chinese admit they kill more than 6,000 a year in their coal mines. SBSP would eliminate the need to mine coal. (I don't expect US citizens to be involved in working in space.)
Back in the dark ages when I was in school,I came up twice in need of an elective course that would fit my work schedule.Both turned out to be real gems.
One could be a business class and for some reason a 400 level advertising class had no prereqs.You can learn more about the dead serious art of selfdeception and how you are taught to practice it upon yourself in one advertising class than you could anywhere else other than a jail cell shared with a wallstreet scam artist or a couple of preachers of the sort Huck and Jim fell afoul of on thier trip dowm the river.
This thing stinks worse of unsolved problems and cost overruns than last weeks chum bait(if you don't know chum is,it's chopped fish scraps) accidentally left in a cooler sitting sitting in the sun in August.You don't even open a cooler of this sort,you VERY CAREFULLY make sure it's latched,wrap your roll of emergency duct tape around it,and put it the nearest dumpster after praying that none of the contents leak along the way.
The other course could be any math course that did not duplicate previous course work.The only thing that would fit was a probability course.It improved my poker game quite a bit.
Now a fundamental law of mathematics states that if you want to know what the likelihood of success is of negotiating a SERIES of problems successfully,you can calculate the probability of succeeding if you know the probability of success of each individual problem by multiplying the probabilities of all problems in the series.
So if you're invited fishing Saturday if the weathers nice,and the probability of nice weather is 60 percent(0.6),if the boat which is in the shop is readynd that probality is 70 percent or 0.7,and the probability that the stripers will still be running is 50 percent or 0.5,and the probability of actually catching one if they are still running is 80 percent or 0.8, then your chance of catching a striper is 0.6times0.7 times0.5 times0.8 or 0.168 or 16.8 percent.
Now if you stop to consider the problems that must be solved to pull of a scheme such as this one,it must become obvious in a hurry that there are hundreds or thousands of critical problems associated with the manufacture of the MATERIALS used just in the airframe alone.I believe that the total mumber of critical problems are beyond actual tabulation,considering the known unknowns alone. Then there are the unknown unknowns to be dealt with.The probability of success would be approaching zero before you even cleared the environmental review.
I can't remember if it was DEEP THOUGHT or the mice that decided the answer to life the universe and everything is 42,but I doubt that even DEEP THOUGHT,who(which?) after all contemplated the vectors of the individual particles of the BIG BANG would want anything to do with actually solving all these problems.
Now on the other hand ,the follies of he human race are beyond comprehension,and I expect that there are thousands of people merrily toiling away at this very instant earning very comfortable salaries on tax payer funded projects which are no more likely to succeed.
Now if you are ever feeling down and need a good laugh,get on down to the bookstore and get all of Mr Douglas Adams books.If you aren't laughing your butt off in ten minutes,you might as well just euthanize yourself,you are too far gone to be saved anyway.
"need a good laugh,get on down to the bookstore and get all of Mr Douglas Adams books."
At least you are a fan of Douglas Adams. :-)
It's not as bad as you think. There are multiple ways to do almost every step in the program, perhaps every step.
Kieth,
I admire your persistence.Apparently you must have some sort(I know knowthing of the various characters involved)of technical background.
If you have not,you can be forgiven for being a true believer.
If you do....maybe you are collecting a salary that depends upon your not understanding?
You can learn enough probability theory in an afternoon to understand why you don't have a clue,if you are proficeint in algebra at the high school level.
At bedtime you will no longer be clueless!
"technical background."
BSEE, wrote space engineering papers with Dr. Eric Drexler as far back as 1977. Interest range to cardiac surgery (Google henson wet work) and evolutionary psychology (two published papers).
"true believer"
I am an engineer, the physics and numbers have to make sense. At the root, the 5 x improvement over previous proposals is due to higher ISP for the laser powered part of the lift to GEO. The "low" $60 B number comes from extensive bootstrapping.
"collecting a salary"
Retired. Not by choice. I am restricted from saying why for another year.
"proficient in algebra"
Non linear differential equations was as far as I got. If you solve one of those, they name it after you. (Bessel for example.)
Re your arguments, the same method can be used to show there is no reasonable chance of doing any large project. Yet they get done.
The reason is that humans faced with a problem figure a way around it. For example, very late in the Manhattan project they found that reactor derived plutonium would not work in a gun type weapon. If you don't know how they got around that, look it up.
There is a slight difference betwee the Manhattan project and SSP. The Manhattan project was a 'costs be dammed, if you produce a handful working nuclear bombs you are as sucess' type of operation. For SSP costs are everything. If the ultimate costs are too high then all of your investment has been for naught.
Kieth,
Your technical qualifications certainly exceed my own by an order of magnitude in terms of engineering.
Normally I would just laugh at someboby making such extravagent claims and thereafter ignore him ,but you seem possessed of a certain incurable optimism kind of like a computer program-you just WILL NOT recognize reality;you just run your data and never consider that since the resulting output is so far out of line with other professionals in the fields you seem so confident about that JUST MAYBE YOU need debugging.Has it ever occured to you that maybe you are NOT the only kid in the band marching in step to the music?
There are such things as time frames,and personell shortages-especially personell capable of inventing,lab testing,prototyping,and putting into production dozens of very high tech nonexistent new machines within my lifetime or yours.
If you are so confident that this can be done why can't a few thousand (I am sure there are that many at least) engineers working on a decent ev battery make faster progress?
"incurable optimism"
I am incredibly pessimistic about this being done in the US. It's possible the US might have a role in it, but probably minor.
"so far out of line with other professionals"
This concept of boosting to GEO from LEO with a laser and then backing off how far up you go with the chemical stage as you add lasers is *under a month old.* The big pieces of it, are *not my work.* All I have done is integrate major pieces by other professionals into a rough pro forma financial model.
How can you say this is out of line with other professionals when virtually none of them know about it?
"personell shortage"
I grant you that. Another reason for it to be done in China.
"working on a decent ev battery make faster progress"
Physics and chemistry. Gasoline has 25 times the energy density of Lithium Ion batteries. When you have to carry both sides of the reaction instead of pulling one out the air, you are never going get the same performance.
What's wrong with carbon neutral gasoline anyway?
Keith,
I enjoyed your post, you have done a great job, but it's clear most are not ready to accept this as an achievable scheme. Lots of weaknesses and technical unknowns. Worth another iteration.
I do not understand your comment about Lithium batteries, the issue with Li is the price, not the range Tesla has shown you can get the EV range, 240 miles is enough for continental US and 99.9% of Australia.
The battery researchers have been putting a lot of time and money into these batteries for DECADES ALREADY.Maybe they will come up with an affordable dependable battery in a few more years.
I don't have any problems with carbon neutral gasoline,but the point is that the batteries are coming slowly..When your project hits a bottleneck and some PREVIOUSLY SATISFACTORY solution to a given problem must be tossed to accomodate the second or third or fourth alternate solution to the bottle neck,you may be only a decade or two-if you are very lucky- behind schedule as a result of this one little bottleneck.Since the bills MUST be paid either cash or credit as they come in,the costs would probably break the world ecomony.
I would not dispute that such a system might someday be built,if after a few decades or centuries most of the problems-such as the manufacture of for instance of cheap carbon fiber structural materials-have been solved as the result of progress in day to day business.Cheap carbon fiber would have countless applications immediately ,so it might make sense-would make sense- to build the infrastructure to manufacture it,and the chain of IF's in the process would only extend from what we know NOW about carbon fiber to what we would need to know THEN to actually strat making the stuff cheaply.I do expect to see carbon fiber used extensively someplace other than in jet aircraft and three thousand dollar bicycles eventually.
Now I am beginning to regret the fact that I started this exchange,as our definitions of day to day reality are obviously incompatable.It's been interesting,but it's also time to say adios.
Exactly. Another excellent post by oldfarmermac, who seems to post no other kind.
The Manhattan project, as cutting-edge as it was, was still rather a brute-force approach. Once you have a critical mass quantity of U235 and the basic concept, you could make a fission bomb out of it in a 19th-century steelmill. (I'll grant that the klystrons required for plutonium were cutting-edge). But it's qualitatively different.
I'm reminded of the Reagan "Star Wars" plan, which if I recall right required the longest software code ever written at the time, couldn't be debugged, and had to work right the first time. Sort of a "reductio ad absurdum" version of the "sequential steps fallacy", yet it burned up a lot of funding.
"I'll grant that the klystrons required for plutonium were cutting-edge."
Klystrons had nothing to do with plutonium. Perhaps you are thinking of the Calutron used to separate out U 235.
You might be amused that Reagan's star wars worked twice. It bankrupted the USSR, and the code went on to be used here: http://silverscorpio.com/mosquito-laser-gun-may-sound-the-death-knell-fo...
I recalled that the timing mechanism using in creating the simultaneous implosion detonations for the Trinity test used klystrons for some ingenious reason, but a quick google doesn't back me up. That's what I get for relying on 40-year-old memories, sorry.
My point about Star Wars was that it wouldn't work as described, not that it wasn't effective theatre.
An anti-mosquito laser - now that's something I could believe in. I actually ordered a green laser powerful enough to burn their wings off, but US customs decided it was a bad idea and kept it for themselves. Presumably worried about ancillary damage to airliners as I challenged the skeeters in my backyard using it as a light sabre.
Still, a device that fires bug-incinerating laser pulses automatically might be a lawsuit waiting to happen, you'd want a parallax sensor to limit shots to close range. And my camera already has a chip in it that will find and lock onto a dozen faces at once, as well as adaptive optics. So I guess the stage is set for a tiny device that automatically blinds people in a combat or crowd-control situation.
and so to bed.
I think the trigger device you are referring to was a "krytron".
d'oh! You're right.
so much for relying on old memories. a little "forbidden planet" must have sneaked in there.
"I recalled that the timing mechanism"
Oh, you mean krytrons. http://en.wikipedia.org/wiki/Krytron
Hi Keith et al:
I'm sure you have spent a lot of time and energy on this project. Good for you. I believe you have a great idea if it will work, finance, physics, PO, etc. but something I didn’t see in your article ...
I worked in Corporate America for a number of years. Read Dilbert. It is a documentary of the high tech real world where you want to go. Figure out if it is at all possible that the pointy haired guy could screw up your plans. If so, plan on it.
If some guy in GEO dropped (not in a literal sense) a critical tool would you have to send him off to get another? The term FUBAR is not new nor do I think it is really gone away with computers. I programmed them for a number of years. In fact I think FUBAR is more prevalent with computers the first few years of most any reasonably complex program.
Right now, every time I change from one link to another I get a JAVA script error. How long has Windows and JAVA been around? Why do I have to click on 'start' to turn off the computer?
I also flew fighters for a number of years and how long will the fleet be down if one of the transports comes apart for some unknown reason? One time I flew test hops and the strangest things can happen with an otherwise old well-used airplane.
I believe all these sorts of things should be included in your computations. I believe it was because the loss of just a nail that a battle was lost. Who would have thought to bring extra nails and horseshoes when you’re all psyched up to go into battle?
Good luck
Lyn
Hope you forgive the pendantic comment, but JavaScript has nothing to do with JAVA. Completely different beasts. It's very unlikely that your browser errors are Java related.
Hi Keith,
Dr. Joy, formerly of San Jose here.
Glad to see that at least some engineers have not given up hope. Very happy to know that you are still so intellectually active.
IMO, SBSP is technically possible and might have already been in place if Earth had been ruled by logical overlords. But instead the last 35 years have been wasted building exurbia, SUVs, and plastic junk from China for WalMart. How many trillions in capital wasted? Unknown, but large and growing.
There is no reason to believe that the human decision making process will improve in the near future.
Idiocracy allows Kleptocracies which means Malthus defeats Kurzweil. Sorry, but I think Jay Hanson had it right with his article on thermo/gene collision.
Best Wishes to you and Arel
"Dr. Joy, formerly of San Jose here."
Ah, good to see you on line.
"MO, SBSP is technically possible and might have already been in place if Earth had been ruled by logical overlords. "
It could have been started back in the late 70s. Different program though. Without low cost laser transport to GEO it would have required Dr. O'Neill's methods of mining the moon for materials and a long build up of space industry.
"Idiocracy allows Kleptocracies which means Malthus defeats Kurzweil"
The US is not the only player in the game. Some countries are ruled by people who understand engineering. I don't know exactly where the cutoff is, but Australia is big enough and there are a dozen companies who could do it if they wanted to.
Good to hear from you. Arel says hi.
We can stay stuck here on earth or spend some (large) amount of money to have a small chance of eventually expanding. I think that is not such a bad idea. Seems a better deal than paying bank CEO's. Low cost (in dollars and greenhouse gas) launch by laser or space elevator would initiate this, ideally at a profit. This will not happen if the Military get ahold of it, but Richard Branson might make it work. Orbital factories/residences/labs would allow us to grasp the concept of living off-planet, just as they are used in the (ant)arctic. These are initially 'tethered' and ideally would slowly become self-supporting. Resource constraints could be defeated by extra-terrestrial mining. Yes, we have to eventually cease the 'go forth and multiply' population issue. But we don't have to be constrained by terrestrial resources. I can see no political hope for digging out of the hole we are in, but wasting money on a long shot lifeboat exercise just might pay off.
The de-orbiting space junk would be a major financial benefit for this project.
But - why geosynchronus orbit? I understand that is a particularly crowded racetrack already. 1/2 GEO is busy with GPS. It would seem to make sense to go to, say 5/4ths GEO and do leapfrog tracking of receivers. Then add one more shell at 4/5 GEO.
I have seen a clever anti-satellite procedure that avoids the discussed orbital nuclear weapons and such. Launch a rock, reverse it around the moon and re-insert it at GEO. At a closing speed of ~8km/s this will remove every satellite in that orbit and (today) leave it unusable for eternity. Having 4 orbital shells at least would require four rocks. Parking every critical satellite in GEO is just asking for Lex Luther to call with a blackmail request. There is already an air-launched missile that approaches this capability.
"But - why geosynchronus orbit? I understand that is a particularly crowded racetrack already. 1/2 GEO is busy with GPS. It would seem to make sense to go to, say 5/4ths GEO and do leapfrog tracking of receivers. Then add one more shell at 4/5 GEO."
That's a reasonable suggestion for when we have thousands of power sats. Something close has been proposed for military use, a large number of small power sats in lower orbits beaming down with small lasers.
I have seen a number of 177 TW available from GEO. I don't know how they figured it.
"rock, reverse it around the moon and re-insert it at GEO. At a closing speed of ~8km/s"
It's only 6 km/sec, not that that makes any difference. Ablation lasers would make short work of any such attempt.
Pissing off people with a multi GW propulsion laser (also known as the "Finger of God") strikes me as a really bad idea.
Have you not considered changing jersey yet , Keith?
Whatever ,at least I'll give you a Hat-tip for your persistency and you obviously do know how UFOs work..