A reasonable economic analysis of power satellites requires about $100/kg for the cost of parts lifted to GEO.
You can't get that with rockets, not even reusable ones.
The main reason is that low exhaust velocity leads to rotten payload fractions. It's just physics, the rocket equation.
The proposed Skylon gets around 9 km/s equivalent exhaust velocity till it runs out of air, and 4.5 km/s from there up. Still too expensive by a factor of 4-5.
Leaving the oxygen out and using a 3 GW laser to heat hydrogen gives around 7.5 km/s for the last 6 km/s to orbit. The laser is hugely expensive, but run 24/7 it costs only a few tens of dollars a kg for 500,000 tons per year.
It's still possible, though I don't see even the excellent work of SpaceX getting us there.
It's not a sure thing that additional development of chemical rockets will do the job. If you go through the math involved, it just doesn't look good.
Space based solar power, for example, has to substantially undercut existing and projected cost per kWh in order for the investment to be worth the trouble. Depends on the numbers you use, but I make a case that the cost of lifting power satellite parts to GEO has to come down to $100/kg for SBSP to make economic sense.
It takes less than a dollar of energy to get a kg to GEO, so the physics doesn't stand in our way. But I don't think you can make a case for rockets getting down to this cost, and if you could, then the volume needed, around 10 million tons per year, just makes rocket lift look really questionable.
The problem traces back to the rotten payload fraction and that's the direct result of low exhaust velocity. However, there may be another way to skin the cat.
Skylon gets the equivalent of 9 km/s to where it runs out of air, and laser heated hydrogen will get at least 7.5 km/s for the rest of the way to orbit. From there to GEO, a hydrogen/laser stage will deliver 2/3rds of a 30 ton second stage in LEO to GEO. Running the laser full time will get three 20 ton vehicles to GEO every hour or about half a million tons per year. Scrap the vehicles at GEO and they are all payload. More details here: http://theenergycollective.com...
When I was much younger, we raised rabbits. For years they were most of the meat the family ate.
I also did every step in making bread. Growing a patch of wheat, harvesting it, thrashing out the grain, grinding grain to flour and baking flour into bread. I can tell you it's a pain.
The most likely thing to happen that would bring down civilization would be running out of cheap energy, especially liquid hydrocarbons for transport. There are several possible ways to get around that problem. This is my proposal. http://theenergycollective.com...
If someone reading this knows Tim, please give him my regards.
Also, if he wants to talk about the whole world going off fossil fuels to a cheap form of solar, be happy to do so. If it can't make dollar a gallon gasoline, then the idea isn't ready for prime time.
"The things that are done in this World in the name of [insert religion - including Buddhists ] is appalling. "
I make a case it is the other way around.
In the former world of hunter-gatherers, the nut corp would fail or the game move away. When that happened,it was necessary to go batshit crazy with xenophobic memes and kill the neighboring tribe. The trait was selected because it promoted genetic survival. It's the underlying resource crisis that causes the appalling behavior. The memes (religions) are in the chain, but not causal.
"Only true end-to-end encryption can be a solution."
I doubt even that. If NAS can't break the encryption, they put a keylogger on your computer and break the encryption that way.
One time pad is a pain in the ass for key management, but it is impossible to break and the NSA may well waste a lot of cycles trying.
Key management here is to keep the keys on your hard drive and do a military grade erase on the blocks you have used.
Sending the key on three memory sticks by different routes and xoring them together seems like it might work. Then fill the sticks several times over with junk files, or if you are really paranoid, burn them. DVDs would work for those without a lot to say.
The question is not about being paranoid, the question is: Are you paranoid enough?
"What if they are tapping into the NSA data for commercial gain? Selling NSA data to other businesses . . . ?"
Or using it either as a company or as individuals. Trawling all the email has got to be the best way to play the stock market ever. Those who can do this can rig the poker game that is the stock market.
Given human nature, can you imagine this *not* being done?
There might be a way to spend a few tens of billions and end the use of fossil fuel by making a certain kind of renewable energy less expensive than fossil fuels. We could burn several times the current consumption of oil and not create any problems if it was carbon neutral synthetic made from really inexpensive electric power.
Dollar a gallon gasoline can be made from 1-2 cent electric power. Ground solar looks like it will bottom out around 8-10 cents per kWh. Space based solar power could get down to 1/5th of that because it gets 5 times as much sunlight in GEO. That's *IF* we can get the transport cost to GEO down to $100/kg. That's about a hundred to one reduction, but looks like it could happen. Details, including some spiffy artwork, here: http://nextbigfuture.com/2013/09/propulsion-lasers-for-large-scale.html
For that you need a good random noise generator (that has not been corrupted by someone), a way to distribute the key material and relatively trivial amount of code. (XOR may be good enough.)
I don't know what is being used recently for random noise. I might want the key generator to be a dedicated hardware box with a couple of storage devices plugged into it, though for a start, a program to run on PCs might be ok.
One problem is key management. You want to delete the used part of the key store, both so you don't reuse it and to keep it from falling into the wrong hands. The obvious way would be to make up USB sticks with files of key material and delete/overwrite the used file blocks. The problem is that secure erasing of files on a USB stick is hard to do.
For casual use for unimportant matters, it might be ok. A more secure method would be to put the key files on a hard drive and use multiple overwrites to erase the used key material.
Eventually someone might make dedicated read once sticks with automatic erasure. Then you would only have to worry about physical security.
"should be funded if, and only if, it is a good idea"
If power satellites are a good idea, they should:
Produce power for half the price of coal. That cheap enough (2 cents per kWh) to make carbon neutral synthetic gasoline for $1-2 per gallon.
Do this while making huge profits. The profits are needed so the power satellite fleet can grow by two TW/year That allows ending human dependence on fossil fuels that will run out (or at least get very expensive) and ending the addition of more CO2 to the atmosphere in a bit over two decades.
Not cause too much of an environmental impact.
Require a transportation investment that isn't any larger than other energy projects. Say $60 B.
Thanks to a suggestion by Steve Nixon in April, it looks like a project of that scale which uses Skylon and laser propulsion can get the cost of lifting parts to GEO down to where power satellites will meet all of the above points except possibly the environmental impact. The model has the 10 year ROI at 500%.
The environmental problem is what dumping from 12 to 240 million tons per year of water into the upper atmosphere near the equator will do to the ozone layer.
The only way we have now that might work is cryonic suspension. I have been signed up with Alcor since 1985, along with Marvin Minsky, Ray Kurzweil and Eric Drexler to name a few. Iain might have enough money handy to pay for it, but in any case I am willing to kick in $500. Perhaps through Kickstarter.
If you think this is a good idea, you might drop a line to Alcor's CEO, Max More, max@alcor.org. Put Iain Banks in the subject line.
I suspect that the US use of drones to kill people because we can will turn around and bite the US in the ass.
Back in November 2012 the Indian delegation to China put out a news release that the Chinese had offered to cooperate with India on power satellites and that the offer would be accepted. There is reason to think the Chinese intend to use laser propulsion to get the cost down to where power satellites make economic sense.
A side effect of such lasers is that they are weapons that obsolete virtually all current weapon systems. But given the US use of drones to kill people the expected US objection isn't going to carry much weight.
"Grand juries are a rubber stamp." That may be true now, and it may have always been common, but the US Attorney's tried to get Phil Zimmermann indicted by two grand juries and failed.
Of course they tried this in Silicon Valley where it may be hard to impanel a grand jury without getting someone with a clue.
It seems to be possible to use space based solar power to displace fossil fuels. The concept is to bootstrap by building one power satellite with conventional rockets and equip it with propulsion lasers. The laser is used to heat hydrogen reaction mass in a fleet of vehicles. The improved performance drops the cost of building power satellites to where they undercut coal by half. With that much of an advantage, energy from space would rapidly take most of the market.
However, a GRB like the 774-775 event would make a mess of satellites, how much would depend on how well they were hardened. But it's possible to imagine an event that killed the satellites and people in space without doing significant damage to the people on the ground. If, as I expect, the only way to get into space by that time was laser propulsion from space, getting the energy supply working again would present serious problems.
Perhaps it will be of no effect. However, the prosecutor isn't going to enjoy the effect, not when she introduces herself and someone says "Oh your are the one who hounded . . .." BTW, the petition is well over halfway to the 25,000 mark.
The model M I am typing on is a Unicomp built 3/31/99, got it direct from Unicomp less than a year ago after my former model M finally died. It's directly plugged in, but there are PS2 to USB adapters that work fine. My wife has one and she types 120 wpm.
On another list someone asked me to explain the press release. Here is my try.
Hypersonic engines are up against hard physics. The ram air heats so
much in the inlet that it's hard for combustion to add much energy to
make it go faster out the back.
The idea behind the SABRE engines is to cool the ram air before it is
compressed. The heat exchanger to do this is what the press release
is all about. With not much more than a ton of mass, it sucks 400 MW
of heat out of the incoming air, dropping the temperature from 1500 C
to -150 C in a few inches of heat exchanger that looks much like
fabric because the tubes are so tiny.
The engine cycle also uses the temperature difference between the ram
air and the LH2 to run the compressor. It takes close to 2/5th of the
energy from burning hydrogen to liquefy it. The engines recover much
of this by running a helium turbine on the temperature difference
between the ram air and the liquid hydrogen flow to the engines. The
turbine powers the compressor stage that raises the pressure of the
-150 C air to rocket chamber pressure.
The design is extremely clever thermodynamics which also avoids most
of the metallurgical problems of high temperature. Fabricating the
air to helium heat exchanger was a very hard task. They have miles of
tiny tubing, tens of thousands of brazed joints and they don't leak!
Using these engines and breathing air, the vehicle reaches 26 km and
about a quarter of the velocity to orbit giving an equivalent exhaust
velocity (back calculate from hydrogen consumption) of 9 km/s.
That's twice as good as the space shuttle main engines. It is
expected to go into orbit with 15 tons of payload out of 300 or 5%
even though the rest of the acceleration is on internal oxygen that
only gives 4.5 km/s exhaust velocity.
Leaving out the oxygen and using big propulsion lasers to heat
hydrogen reaction mass, such a vehicle would get 25% of takeoff mass
to LEO, reducing the already low cost by a factor of 5. That's enough
to change the economics of power satellites from being too expensive
to consider to a cost substantially less expensive than any fossil
fuel.
But try explaining any of this in a press release.
Slashdot Mirror
Musk is right.
A reasonable economic analysis of power satellites requires about $100/kg for the cost of parts lifted to GEO.
You can't get that with rockets, not even reusable ones.
The main reason is that low exhaust velocity leads to rotten payload fractions. It's just physics, the rocket equation.
The proposed Skylon gets around 9 km/s equivalent exhaust velocity till it runs out of air, and 4.5 km/s from there up. Still too expensive by a factor of 4-5.
Leaving the oxygen out and using a 3 GW laser to heat hydrogen gives around 7.5 km/s for the last 6 km/s to orbit. The laser is hugely expensive, but run 24/7 it costs only a few tens of dollars a kg for 500,000 tons per year.
More here: http://theenergycollective.com...
Keith
It's still possible, though I don't see even the excellent work of SpaceX getting us there.
It's not a sure thing that additional development of chemical rockets will do the job. If you go through the math involved, it just doesn't look good.
Space based solar power, for example, has to substantially undercut existing and projected cost per kWh in order for the investment to be worth the trouble. Depends on the numbers you use, but I make a case that the cost of lifting power satellite parts to GEO has to come down to $100/kg for SBSP to make economic sense.
It takes less than a dollar of energy to get a kg to GEO, so the physics doesn't stand in our way. But I don't think you can make a case for rockets getting down to this cost, and if you could, then the volume needed, around 10 million tons per year, just makes rocket lift look really questionable.
The problem traces back to the rotten payload fraction and that's the direct result of low exhaust velocity. However, there may be another way to skin the cat.
Skylon gets the equivalent of 9 km/s to where it runs out of air, and laser heated hydrogen will get at least 7.5 km/s for the rest of the way to orbit. From there to GEO, a hydrogen/laser stage will deliver 2/3rds of a 30 ton second stage in LEO to GEO. Running the laser full time will get three 20 ton vehicles to GEO every hour or about half a million tons per year. Scrap the vehicles at GEO and they are all payload. More details here: http://theenergycollective.com...
Keith Henson
http://en.wikipedia.org/wiki/L...
When I was much younger, we raised rabbits. For years they were most of the meat the family ate.
I also did every step in making bread. Growing a patch of wheat, harvesting it, thrashing out the grain, grinding grain to flour and baking flour into bread. I can tell you it's a pain.
The most likely thing to happen that would bring down civilization would be running out of cheap energy, especially liquid hydrocarbons for transport. There are several possible ways to get around that problem. This is my proposal. http://theenergycollective.com...
If someone reading this knows Tim, please give him my regards.
Also, if he wants to talk about the whole world going off fossil fuels to a cheap form of solar, be happy to do so. If it can't make dollar a gallon gasoline, then the idea isn't ready for prime time.
http://nextbigfuture.com/2013/...
Talk I gave at Google.
http://youtu.be/qCiw99yRBo8
A laser 33 times larger than the propulsion laser I propose.
http://www.deepspace.ucsb.edu/...
http://en.wikipedia.org/wiki/L...
"The things that are done in this World in the name of [insert religion - including Buddhists ] is appalling. "
I make a case it is the other way around.
In the former world of hunter-gatherers, the nut corp would fail or the game move away. When that happened ,it was necessary to go batshit crazy with xenophobic memes and kill the neighboring tribe. The trait was selected because it promoted genetic survival. It's the underlying resource crisis that causes the appalling behavior. The memes (religions) are in the chain, but not causal.
There is actually good reason from evolution to think these models are correct.
I wrote about this some years ago. Evolutionary Psychology, Memes and the Origin of War. It was published in an academic journal, but this version,
http://www.kuro5hin.org/story/...
is not behind a paywall.
"Only true end-to-end encryption can be a solution."
I doubt even that. If NAS can't break the encryption, they put a keylogger on your computer and break the encryption that way.
One time pad is a pain in the ass for key management, but it is impossible to break and the NSA may well waste a lot of cycles trying.
Key management here is to keep the keys on your hard drive and do a military grade erase on the blocks you have used.
Sending the key on three memory sticks by different routes and xoring them together seems like it might work. Then fill the sticks several times over with junk files, or if you are really paranoid, burn them. DVDs would work for those without a lot to say.
The question is not about being paranoid, the question is: Are you paranoid enough?
"What if they are tapping into the NSA data for commercial gain? Selling NSA data to other businesses . . . ?"
Or using it either as a company or as individuals. Trawling all the email has got to be the best way to play the stock market ever. Those who can do this can rig the poker game that is the stock market.
Given human nature, can you imagine this *not* being done?
There might be a way to spend a few tens of billions and end the use of fossil fuel by making a certain kind of renewable energy less expensive than fossil fuels. We could burn several times the current consumption of oil and not create any problems if it was carbon neutral synthetic made from really inexpensive electric power.
Dollar a gallon gasoline can be made from 1-2 cent electric power. Ground solar looks like it will bottom out around 8-10 cents per kWh. Space based solar power could get down to 1/5th of that because it gets 5 times as much sunlight in GEO. That's *IF* we can get the transport cost to GEO down to $100/kg. That's about a hundred to one reduction, but looks like it could happen. Details, including some spiffy artwork, here: http://nextbigfuture.com/2013/09/propulsion-lasers-for-large-scale.html
"and would never actually send child porn to anyone to make a case?"
They did it to Robert Thomas in the Amateur Action BBS case. Almost 20 years ago.
http://www.zoklet.net/totse/en/law/high_profile_legal_cases/aabust.html
Charged him too. But even a jury of Sunday School teachers didn't convict on that particular charge.
The best project management tool I ever used was Lisa Project. NASA used it as long as they could and were lost when it could no longer be supported.
Has anyone revived it?
One time pads are unbreakable if used properly.
For that you need a good random noise generator (that has not been corrupted by someone), a way to distribute the key material and relatively trivial amount of code. (XOR may be good enough.)
I don't know what is being used recently for random noise. I might want the key generator to be a dedicated hardware box with a couple of storage devices plugged into it, though for a start, a program to run on PCs might be ok.
One problem is key management. You want to delete the used part of the key store, both so you don't reuse it and to keep it from falling into the wrong hands. The obvious way would be to make up USB sticks with files of key material and delete/overwrite the used file blocks. The problem is that secure erasing of files on a USB stick is hard to do.
http://www.theregister.co.uk/2011/02/21/flash_drive_erasing_peril/
http://www.usenix.org/events/fast11/tech/full_papers/Wei.pdf
For casual use for unimportant matters, it might be ok. A more secure method would be to put the key files on a hard drive and use multiple overwrites to erase the used key material.
Eventually someone might make dedicated read once sticks with automatic erasure. Then you would only have to worry about physical security.
"should be funded if, and only if, it is a good idea"
If power satellites are a good idea, they should:
Produce power for half the price of coal. That cheap enough (2 cents per kWh) to make carbon neutral synthetic gasoline for $1-2 per gallon.
Do this while making huge profits. The profits are needed so the power satellite fleet can grow by two TW/year That allows ending human dependence on fossil fuels that will run out (or at least get very expensive) and ending the addition of more CO2 to the atmosphere in a bit over two decades.
Not cause too much of an environmental impact.
Require a transportation investment that isn't any larger than other energy projects. Say $60 B.
Thanks to a suggestion by Steve Nixon in April, it looks like a project of that scale which uses Skylon and laser propulsion can get the cost of lifting parts to GEO down to where power satellites will meet all of the above points except possibly the environmental impact. The model has the 10 year ROI at 500%.
The environmental problem is what dumping from 12 to 240 million tons per year of water into the upper atmosphere near the equator will do to the ozone layer.
Not surprised. What I do expect is that someone will be caught, maybe some very senior people, using the trawl to play the stock market.
"back him up"
The only way we have now that might work is cryonic suspension. I have been signed up with Alcor since 1985, along with Marvin Minsky, Ray Kurzweil and Eric Drexler to name a few. Iain might have enough money handy to pay for it, but in any case I am willing to kick in $500. Perhaps through Kickstarter.
If you think this is a good idea, you might drop a line to Alcor's CEO, Max More, max@alcor.org. Put Iain Banks in the subject line.
I suspect that the US use of drones to kill people because we can will turn around and bite the US in the ass.
Back in November 2012 the Indian delegation to China put out a news release that the Chinese had offered to cooperate with India on power satellites and that the offer would be accepted. There is reason to think the Chinese intend to use laser propulsion to get the cost down to where power satellites make economic sense.
A side effect of such lasers is that they are weapons that obsolete virtually all current weapon systems. But given the US use of drones to kill people the expected US objection isn't going to carry much weight.
Assuming the US understands the consequences.
I would give serious thought to buying some CAT5 cable and turning the WIFI off.
I won't deal with AT&T for what they did to Len Rose years ago. http://en.wikipedia.org/wiki/Leonard_Rose_(hacker)
"Grand juries are a rubber stamp." That may be true now, and it may have always been common, but the US Attorney's tried to get Phil Zimmermann indicted by two grand juries and failed.
Of course they tried this in Silicon Valley where it may be hard to impanel a grand jury without getting someone with a clue.
It seems to be possible to use space based solar power to displace fossil fuels. The concept is to bootstrap by building one power satellite with conventional rockets and equip it with propulsion lasers. The laser is used to heat hydrogen reaction mass in a fleet of vehicles. The improved performance drops the cost of building power satellites to where they undercut coal by half. With that much of an advantage, energy from space would rapidly take most of the market.
However, a GRB like the 774-775 event would make a mess of satellites, how much would depend on how well they were hardened. But it's possible to imagine an event that killed the satellites and people in space without doing significant damage to the people on the ground. If, as I expect, the only way to get into space by that time was laser propulsion from space, getting the energy supply working again would present serious problems.
Perhaps it will be of no effect. However, the prosecutor isn't going to enjoy the effect, not when she introduces herself and someone says "Oh your are the one who hounded . . . ." BTW, the petition is well over halfway to the 25,000 mark.
Around 1980 the L5 Society defeated the Moon Treaty. Personal experience, got to testify before Congress.
I can see it now, student with a ring of rubber fingers signing in a mess of students to a video lecture.
The model M I am typing on is a Unicomp built 3/31/99, got it direct from Unicomp less than a year ago after my former model M finally died. It's directly plugged in, but there are PS2 to USB adapters that work fine. My wife has one and she types 120 wpm.
On another list someone asked me to explain the press release. Here is my try.
Hypersonic engines are up against hard physics. The ram air heats so much in the inlet that it's hard for combustion to add much energy to make it go faster out the back.
The idea behind the SABRE engines is to cool the ram air before it is compressed. The heat exchanger to do this is what the press release is all about. With not much more than a ton of mass, it sucks 400 MW of heat out of the incoming air, dropping the temperature from 1500 C to -150 C in a few inches of heat exchanger that looks much like fabric because the tubes are so tiny.
The engine cycle also uses the temperature difference between the ram air and the LH2 to run the compressor. It takes close to 2/5th of the energy from burning hydrogen to liquefy it. The engines recover much of this by running a helium turbine on the temperature difference between the ram air and the liquid hydrogen flow to the engines. The turbine powers the compressor stage that raises the pressure of the -150 C air to rocket chamber pressure.
The design is extremely clever thermodynamics which also avoids most of the metallurgical problems of high temperature. Fabricating the air to helium heat exchanger was a very hard task. They have miles of tiny tubing, tens of thousands of brazed joints and they don't leak!
Using these engines and breathing air, the vehicle reaches 26 km and about a quarter of the velocity to orbit giving an equivalent exhaust velocity (back calculate from hydrogen consumption) of 9 km/s. That's twice as good as the space shuttle main engines. It is expected to go into orbit with 15 tons of payload out of 300 or 5% even though the rest of the acceleration is on internal oxygen that only gives 4.5 km/s exhaust velocity.
Leaving out the oxygen and using big propulsion lasers to heat hydrogen reaction mass, such a vehicle would get 25% of takeoff mass to LEO, reducing the already low cost by a factor of 5. That's enough to change the economics of power satellites from being too expensive to consider to a cost substantially less expensive than any fossil fuel.
But try explaining any of this in a press release.