What about a Sabatier reaction? 2H20 -> 2H2 + O2 | CO2 + 2H2 -> CH4 + O2. I know that Zubrin in his Case for MArs stuff built a fairly high efficiency setup that fit onto a pegboard. IIRC, the synthesis rate wasn't too spectacular but it's a process that can be scaled up fairly easily.
I did a Google and there are actually commercially available systems out there that are being sold for power conditioning and UPS service for businesses. They use liquid He and old school superconductors because of teh higher current density possible. There's still talk of city scale units but it sounds like the economics haven't caught up to practicality of those just yet.
Yeah, as long as you keep purifying the water, it would work. Unfortunately, ions leaching off of the parts and CO2 going into solution greatly increase the conductivity. The systems for keeping the water low conductivity are fairly simple but expensive and a pain to keep running 24/7. It's actually used for high powered lasers where costs isn't much of an object.
Large scale energy storage is particularly important for solar adoption. Right now, the sell-back system with the power grid works since there's only small amounts of power coming from home power grids. However, as soon as it goes mass-market, the off-peak power market's going to implode. While that's great for aluminum refiners, it means that the economic advantage of solar is largely negated.
Whatever happened to the idea of superconducting power rings? Did the magnetic flux intensity just prove too great for practical use?
Unfortunately, that's largely true. Although solar has made inroads on things like shipboard use and little garden lights, most people just don't think of it as a primary power source.
I suspect that once solar power gets to the point where it can pay for itself in under a year, you'll see public attention start hitting it. I am encouraged by those little solar powered lawn lgihts, though. As cheesy as they are, they are popular and start to subconciously affect people to think that 'Hey, solar power *does* work!"
The fact that most people miss is that solar cells have started to push past this goal. They now take less energy to manufacture than they capture in their lifetime (always a bonus), and the cost per kWh is pushing down to 2-3 times grid electricity. Given that solar cells have demonstrated a steady decline in cost for the past few decades, chances are good that we'll start seeing large scale adoption in the next decade.
There's also other factor encouraging the use of solar cells. For one, they're much more durable. There's some cells now that can be used rdirectly as roofing tiles where you can put nails through them and walk on them. They aren't the best panels out there but the ruggedness factor is attractive. Also, most power companies now let you sell off excess capacity back to the power grid these days. That development alone can make solar cell arrays in sunny areas pay for themselves in 10 years or so.
Unfortunately, I live in Seattle, land of little direct sunlight and no steady wind. Renewable energy for me is out until those solar cells get another 50% decline in $/kWh.
I'm a bit torn between marvelling at the genius and the stupidity of someone willing to pretend to be an international arms dealer for the sake of art and a few yuks.
While quantum cryptography is something we should be concerned about, it won't allow governments and organizations to operate without accountability. From what I understand about state of the art quantum 'cryptography', it's purely a means to ensure that no one is listening in on your communication line. The actual cryptography on both ends is no more unbeatable than what already exists.
Also, you've still got other lines of evidence - bodies, eye witnesses, etc.
The last time quantum cryptography came up on Slashdot, someone had a fabulous analogy. They compared a secure system to a fence. Quantum cryptography to building a giant, reinforced concrete pillar for one of the posts and having the rest of the fence be made of chicken wire and 2x4's. Unless you've made extraordinary efforts towards securing the human and nonquantum computer elements of your system, the quantum cryptography is fairly useless.
Getting SpaceShipOne up to LEO just requires a larger carrier arcraft and more powerful, higher Isp boosters. (About 12 times bigger but at least that's something that can be attacked with standard aerospace engineering) The reentry is where the problem is at. 17,000 mph is a lot of speed to bleed off. The current SpaceShipOne design isn't capable of mounting the heat shielding necessary to survive those kinds of thermal loads.
I'd seen figures closer to 12 times as much energy but the difference is largely academic. Either way, geting to LEO is expensive. However, I'd expect to see an X2 prize being offered to get to LEO after this. Remember that a lot of the high costs of LEO launchers are artificial. The fuel is usually about 2% of the total launch cost. The rest is all those launch technicians and the cost of all those non-reusable rocket parts.
Boeing has managed to capitalize on reducing the launch technician side of things along with using cheaper Ukranian parts to get launch costs down to about $5000/kg to LEO with Sea Launch. That's half the cost of their own Delta launchers. The DC-X several years ago had real promise of beinga practical SSTO, massively cutting launch costs. Unfortunately, NASA axed it, seeing it as a competitor. The hope is that the rise of private companies that aren't tied to NASA politics will be able to eventually replicate the work done on the DC-X and actually get some real progress on cheap orbital launches rather than the technology of the month approach NASA's been dumping money down the last 20 years.
True, 100 km is old stuff for NASA but it's still quite useful. There's the whole space tourism for 1/10th the cost angle which does have appeal. The Russians are building a space plane (another X Prize contestant, BTW) for that very purpose. I don't know what the maximum downrange for SpaceShipOne is but it has great potential for moving small numbers of people and freight at high speeds. Need to send someone or something from LA to New York in 1.5 hours for $100K a pop? There's a solid, profitable business right there.
True, it's basically a test of designs at this point. Rutan and company could probably go for the X Prize tomorrow is they felt like it but at great risk to the pilots. Conversely, they might find out that at mach 3, SpaceShipOne has unfixable stability problems. Basically, that's back to the drawing board and all chances for a win are gone then.
However, sing as how no other team has even tested a full scale demonstrator yet, Rutan is firmly in the lead. Armadillo hasn't even figured out their entire landing proceedure yet. It's hard to figure out where Da Vinci is at since they're site is somewhat short on details. It took a while to even figure out that they had physical components ready. Unless something goes wrong, it's hard to see anyone passing Scaled at this point.
According to the article, *COUGH COUGH RTFA COUGH*, Scaled has been keeping largely mum so far but has admitted that the flight did occur and that post flight handling analysis is going on. Expect a website update in a day or two.
As another poster pointed out, 100K feet is about the maximum altitude where flaps still give aerodynamic control. Above that, they're going to have to depend upon the attitude control system. My guess is that the next flight will go to slightly over 100K feet and test those systems out.
After that, there will probably be a series of flights progressively going higher and faster to test out the high speed handling of the craft. Rutan is known for being very methodical about testing new designs.
After that, they'll probably start doing a few flights to 300K+ feet to make sure that everything works correctly. After that, they'll load on the two extra passengers and prepare to make the two flights in one week necessary to get the prize. (just hitting the altitude doesn't get you the prize) Knowing Rutan, he'll probably throw in a couple more flights in that first week just to show off.
Drat, someone beat me on the article submission. At least this time, the editors will finally have a decent reason to reject my submission, though.
Unless something goes seriously wrong with Scaled's program, it looks they've got the thing pretty much sewn up. The only serious competitors to Scaled right now are Carmack's Armadillo and those craaazy Canucks on the Da Vinci project. Given that this is almost exactly 1/3 of the way to the X Prize and that they already have broken the red tape barrier, I have trouble seeing anyone catching up to Rutan and crew at this point.
Also, there are serious doubts as to just how useful those Helium 3 deposits actually are. They are believed to be present in the part-per-billion concentrations. Finding methods to extract useful amounts of the stuff are still hypothetical.
You seriously underestimate the amount of power needed for this. If you're trying to grow actual crop plants for food, the power required to keep them growing theough the 2-week nights is tremendous. Remember that ordinary plants require about 1 kW/m^2 to function properly. The sort of nuclear reactors that are being proposed for these missions (100kW) are enough to light up a patch of vegetables with the footprint of a small house.
Also, the intensity of the sun and the unfiltered radiation would be deadly to plants, requiring glass several inches thick. Some sort of mirror system would probably be required, further adding to the complexity.
However, since it's likely that the lunar base will be at the South pole, there are peaks there that are in sunlight 24/7. I suppose that a greenhouse fed by mirrors could be set up there.
The book was Integral Trees and IMO was the best book Niven has done. The trees actually rotated - the ends of the trees were funnel shaped to collect water and nutrients. The habitation was in a large gas cloud in orbit around a quiescent neutron star.
I'm sure that the spysics made no sense but it was a cool story anyway.
Niven is either on or really off in my experience. IMO, he's not that great of a writer even at his best but his settings often make up for that shortcoming. When he's off, though...
I can't remember the title but there was a Niven novel set in a future arcology in LA - one of the worst pieces of dreck I've ever read. I had trouble believing that is was written by the same person.
"Lots of people set their pants on fire and went off in funny directions when they tried them out," says Austin Williams of the independent Transport Research Group.
That's about the best advantage I saw in the whole group!
Slashdot Mirror
What about a Sabatier reaction? 2H20 -> 2H2 + O2 | CO2 + 2H2 -> CH4 + O2. I know that Zubrin in his Case for MArs stuff built a fairly high efficiency setup that fit onto a pegboard. IIRC, the synthesis rate wasn't too spectacular but it's a process that can be scaled up fairly easily.
I did a Google and there are actually commercially available systems out there that are being sold for power conditioning and UPS service for businesses. They use liquid He and old school superconductors because of teh higher current density possible. There's still talk of city scale units but it sounds like the economics haven't caught up to practicality of those just yet.
Actually, the equilibrium of H20 -> H+ + OH- is almost entirely due to thermodynamic concerns, not ionizing radiation.
Yeah, as long as you keep purifying the water, it would work. Unfortunately, ions leaching off of the parts and CO2 going into solution greatly increase the conductivity. The systems for keeping the water low conductivity are fairly simple but expensive and a pain to keep running 24/7. It's actually used for high powered lasers where costs isn't much of an object.
Large scale energy storage is particularly important for solar adoption. Right now, the sell-back system with the power grid works since there's only small amounts of power coming from home power grids. However, as soon as it goes mass-market, the off-peak power market's going to implode. While that's great for aluminum refiners, it means that the economic advantage of solar is largely negated.
Whatever happened to the idea of superconducting power rings? Did the magnetic flux intensity just prove too great for practical use?
Unfortunately, that's largely true. Although solar has made inroads on things like shipboard use and little garden lights, most people just don't think of it as a primary power source.
I suspect that once solar power gets to the point where it can pay for itself in under a year, you'll see public attention start hitting it. I am encouraged by those little solar powered lawn lgihts, though. As cheesy as they are, they are popular and start to subconciously affect people to think that 'Hey, solar power *does* work!"
The fact that most people miss is that solar cells have started to push past this goal. They now take less energy to manufacture than they capture in their lifetime (always a bonus), and the cost per kWh is pushing down to 2-3 times grid electricity. Given that solar cells have demonstrated a steady decline in cost for the past few decades, chances are good that we'll start seeing large scale adoption in the next decade.
There's also other factor encouraging the use of solar cells. For one, they're much more durable. There's some cells now that can be used rdirectly as roofing tiles where you can put nails through them and walk on them. They aren't the best panels out there but the ruggedness factor is attractive. Also, most power companies now let you sell off excess capacity back to the power grid these days. That development alone can make solar cell arrays in sunny areas pay for themselves in 10 years or so.
Unfortunately, I live in Seattle, land of little direct sunlight and no steady wind. Renewable energy for me is out until those solar cells get another 50% decline in $/kWh.
Mod the parent and grandparent messages up.
I'm a bit torn between marvelling at the genius and the stupidity of someone willing to pretend to be an international arms dealer for the sake of art and a few yuks.
While quantum cryptography is something we should be concerned about, it won't allow governments and organizations to operate without accountability. From what I understand about state of the art quantum 'cryptography', it's purely a means to ensure that no one is listening in on your communication line. The actual cryptography on both ends is no more unbeatable than what already exists.
Also, you've still got other lines of evidence - bodies, eye witnesses, etc.
The last time quantum cryptography came up on Slashdot, someone had a fabulous analogy. They compared a secure system to a fence. Quantum cryptography to building a giant, reinforced concrete pillar for one of the posts and having the rest of the fence be made of chicken wire and 2x4's. Unless you've made extraordinary efforts towards securing the human and nonquantum computer elements of your system, the quantum cryptography is fairly useless.
Getting SpaceShipOne up to LEO just requires a larger carrier arcraft and more powerful, higher Isp boosters. (About 12 times bigger but at least that's something that can be attacked with standard aerospace engineering) The reentry is where the problem is at. 17,000 mph is a lot of speed to bleed off. The current SpaceShipOne design isn't capable of mounting the heat shielding necessary to survive those kinds of thermal loads.
I'd seen figures closer to 12 times as much energy but the difference is largely academic. Either way, geting to LEO is expensive. However, I'd expect to see an X2 prize being offered to get to LEO after this. Remember that a lot of the high costs of LEO launchers are artificial. The fuel is usually about 2% of the total launch cost. The rest is all those launch technicians and the cost of all those non-reusable rocket parts.
Boeing has managed to capitalize on reducing the launch technician side of things along with using cheaper Ukranian parts to get launch costs down to about $5000/kg to LEO with Sea Launch. That's half the cost of their own Delta launchers. The DC-X several years ago had real promise of beinga practical SSTO, massively cutting launch costs. Unfortunately, NASA axed it, seeing it as a competitor. The hope is that the rise of private companies that aren't tied to NASA politics will be able to eventually replicate the work done on the DC-X and actually get some real progress on cheap orbital launches rather than the technology of the month approach NASA's been dumping money down the last 20 years.
True, 100 km is old stuff for NASA but it's still quite useful. There's the whole space tourism for 1/10th the cost angle which does have appeal. The Russians are building a space plane (another X Prize contestant, BTW) for that very purpose. I don't know what the maximum downrange for SpaceShipOne is but it has great potential for moving small numbers of people and freight at high speeds. Need to send someone or something from LA to New York in 1.5 hours for $100K a pop? There's a solid, profitable business right there.
True, it's basically a test of designs at this point. Rutan and company could probably go for the X Prize tomorrow is they felt like it but at great risk to the pilots. Conversely, they might find out that at mach 3, SpaceShipOne has unfixable stability problems. Basically, that's back to the drawing board and all chances for a win are gone then.
However, sing as how no other team has even tested a full scale demonstrator yet, Rutan is firmly in the lead. Armadillo hasn't even figured out their entire landing proceedure yet. It's hard to figure out where Da Vinci is at since they're site is somewhat short on details. It took a while to even figure out that they had physical components ready. Unless something goes wrong, it's hard to see anyone passing Scaled at this point.
According to the article, *COUGH COUGH RTFA COUGH*, Scaled has been keeping largely mum so far but has admitted that the flight did occur and that post flight handling analysis is going on. Expect a website update in a day or two.
Oh yeah, almost forgot, the cabin is pressurized. So no pressure suits are required.
As another poster pointed out, 100K feet is about the maximum altitude where flaps still give aerodynamic control. Above that, they're going to have to depend upon the attitude control system. My guess is that the next flight will go to slightly over 100K feet and test those systems out.
After that, there will probably be a series of flights progressively going higher and faster to test out the high speed handling of the craft. Rutan is known for being very methodical about testing new designs.
After that, they'll probably start doing a few flights to 300K+ feet to make sure that everything works correctly. After that, they'll load on the two extra passengers and prepare to make the two flights in one week necessary to get the prize. (just hitting the altitude doesn't get you the prize) Knowing Rutan, he'll probably throw in a couple more flights in that first week just to show off.
Drat, someone beat me on the article submission. At least this time, the editors will finally have a decent reason to reject my submission, though.
Unless something goes seriously wrong with Scaled's program, it looks they've got the thing pretty much sewn up. The only serious competitors to Scaled right now are Carmack's Armadillo and those craaazy Canucks on the Da Vinci project. Given that this is almost exactly 1/3 of the way to the X Prize and that they already have broken the red tape barrier, I have trouble seeing anyone catching up to Rutan and crew at this point.
Also, there are serious doubts as to just how useful those Helium 3 deposits actually are. They are believed to be present in the part-per-billion concentrations. Finding methods to extract useful amounts of the stuff are still hypothetical.
Hmm, yet another Slashcode irritation...
That should have read ( 100KW)
You seriously underestimate the amount of power needed for this. If you're trying to grow actual crop plants for food, the power required to keep them growing theough the 2-week nights is tremendous. Remember that ordinary plants require about 1 kW/m^2 to function properly. The sort of nuclear reactors that are being proposed for these missions (100kW) are enough to light up a patch of vegetables with the footprint of a small house.
Also, the intensity of the sun and the unfiltered radiation would be deadly to plants, requiring glass several inches thick. Some sort of mirror system would probably be required, further adding to the complexity.
However, since it's likely that the lunar base will be at the South pole, there are peaks there that are in sunlight 24/7. I suppose that a greenhouse fed by mirrors could be set up there.
Oops, that should read physics, not spysics....
Preview button? What preview button?
The book was Integral Trees and IMO was the best book Niven has done. The trees actually rotated - the ends of the trees were funnel shaped to collect water and nutrients. The habitation was in a large gas cloud in orbit around a quiescent neutron star.
I'm sure that the spysics made no sense but it was a cool story anyway.
Niven is either on or really off in my experience. IMO, he's not that great of a writer even at his best but his settings often make up for that shortcoming. When he's off, though...
I can't remember the title but there was a Niven novel set in a future arcology in LA - one of the worst pieces of dreck I've ever read. I had trouble believing that is was written by the same person.
Under Jetpack disadvantages, they list:
"Lots of people set their pants on fire and went off in funny directions when they tried them out," says Austin Williams of the independent Transport Research Group.
That's about the best advantage I saw in the whole group!