ALL containers leak. It's call "diffusion" and it happens across any surface when there's a pressure gradient. If you fill a bottle with hydrogen, there is a pressure gradient - the partial pressure of hydrogen inside is greater than that outside, and the bottle leaks. The case made that hydrogen is "small" does hold water - hydrogen will diffuse across a surface faster than, say, helium or sulfur hexafluoride, because it's smaller. Size does matter, even in atomic physics.
("Diffusion", by the way, is one way to, for instance, dope a semiconductor. So, yes, things move around in crystals all the time, even metals through other metals.)
I guess what you say in your last paragraph is the biggest part of what I was getting at - I appreciate your critique and realize that, no, asteroid mining is not feasible and not particularly necessary today. But as demand grows, it will be a resource we will want to turn to, and those high barriers to space that make it fiscally undesirable will only come down when somebody makes the financial effort to do it.
This is certainly true. Ideas like the space elevator are a step in the right direction - you could affix an ion drive to the asteroid, maneuver it into a parking orbit, mine it and send the processed product down an elevator or some such.
'course, you don't want it in too close an orbit or else you've got a much bigger problem.;o)
Answer: ion propulsion. It doesn't have nearly the thrust of a chemical rocket, but a) is about an order of magnitude more efficient (as measure in terms of specific impulse), and b) can, with a bit of time, get plenty fast. This is the most likely propulsion technology to be used for intrasystem travel in the near future.
Going to Mars is important. It is, if nothing else, a proof of concept - going to Mars is orders of magnitude more difficult than going to the Moon. It requires better propulsion, better equipment, more efficiency and the planning and execution to see a group of people through a multi-year mission to another planet and back. If we can go to Mars, we can (with minimal additional scaling effects) go anywhere in the Solar System. This (other than scientific research) is the purpose of going to Mars, no more and no less.
"What's so great about that?" you might ask. If you want it in one word, that word is "Mining". Consider: in a nickel-iron asteroid, there is an amount of metal roughly equivalent to the metal mined in the course of human history. Not to mention rare heavy metals - Iridium, Osmium, Platinum - things that are scarce on earth but relatively more abundant in asteroids. A mining operation of that scale is more than lucrative - it also presents a way to attain necessary raw materials without tearing open the surface of our own planet.
But, yeah, mostly, it's the money. Money is the key - and I don't mean "having enough money to do these things". What I mean is opportunities for profit in space. Space travel currently costs a lot - I maintain that this is due to lack of expertise. If there is a sufficient profit motive in space, companies will find ways to do things cheaper and faster and, arguably, better (not being a terrible believer in an unregulated market, this last point is debatable). Prove that we can go get to the money, and people will go get it.
Which brings me to my last point - spending philosophy. A lot of people decry spending on the space program, arguing that the greatest benefits have come from near-Earth satellites and such; and besides, they say, aren't there better things to spend the money on? This is true, in a sense. But, I, for one, would rather spend another billion dollars on the space program, on research and development, than on a new B2 bomber that doesn't work the way it should and whose role as a long-range strategic bomber was obviated by the end of the Cold War. Finding a more worthy cause - education, health care, welfare - does not eliminate the need to spend on less worthy causes. The point is, we don't know yet what we might find worthy in space. It is a money sink until we find that. I think it is worth examining - with plans like reuseable launch vehicles and space elevators and Lagrange-point stations, we have a number of ways to lower the financial barriers to space.
I am not generally one to talk so, but I think we have a responsibility to future generations and to our own sense of intellectual completeness to reach into space. The cost will be mitigated over time. The benefits could be grand. The investment will surely be prohibitive. The continued and future examination and implementation of space travel depend on a long-term view of the investment, a willingness to look for opportunities, and a certain modicum of childlike wonder and hope. Space is great. It's just hard to get to right now.
Slashdot Mirror
And this gets modded "Insightful"? At least it only got a two. Thanks for the obligatory knee-jerk reaction.
ALL containers leak. It's call "diffusion" and it happens across any surface when there's a pressure gradient. If you fill a bottle with hydrogen, there is a pressure gradient - the partial pressure of hydrogen inside is greater than that outside, and the bottle leaks. The case made that hydrogen is "small" does hold water - hydrogen will diffuse across a surface faster than, say, helium or sulfur hexafluoride, because it's smaller. Size does matter, even in atomic physics.
("Diffusion", by the way, is one way to, for instance, dope a semiconductor. So, yes, things move around in crystals all the time, even metals through other metals.)
-_- By which I mean "amorphous". Spelling-- ...
The article refers to them as alumina glasses, so, uh, "amorphouse". A glass is by definition not a crystal.
I guess what you say in your last paragraph is the biggest part of what I was getting at - I appreciate your critique and realize that, no, asteroid mining is not feasible and not particularly necessary today. But as demand grows, it will be a resource we will want to turn to, and those high barriers to space that make it fiscally undesirable will only come down when somebody makes the financial effort to do it.
This is certainly true. Ideas like the space elevator are a step in the right direction - you could affix an ion drive to the asteroid, maneuver it into a parking orbit, mine it and send the processed product down an elevator or some such. 'course, you don't want it in too close an orbit or else you've got a much bigger problem. ;o)
Answer: ion propulsion. It doesn't have nearly the thrust of a chemical rocket, but a) is about an order of magnitude more efficient (as measure in terms of specific impulse), and b) can, with a bit of time, get plenty fast. This is the most likely propulsion technology to be used for intrasystem travel in the near future.
Going to Mars is important. It is, if nothing else, a proof of concept - going to Mars is orders of magnitude more difficult than going to the Moon. It requires better propulsion, better equipment, more efficiency and the planning and execution to see a group of people through a multi-year mission to another planet and back. If we can go to Mars, we can (with minimal additional scaling effects) go anywhere in the Solar System. This (other than scientific research) is the purpose of going to Mars, no more and no less.
"What's so great about that?" you might ask. If you want it in one word, that word is "Mining". Consider: in a nickel-iron asteroid, there is an amount of metal roughly equivalent to the metal mined in the course of human history. Not to mention rare heavy metals - Iridium, Osmium, Platinum - things that are scarce on earth but relatively more abundant in asteroids. A mining operation of that scale is more than lucrative - it also presents a way to attain necessary raw materials without tearing open the surface of our own planet.
But, yeah, mostly, it's the money. Money is the key - and I don't mean "having enough money to do these things". What I mean is opportunities for profit in space. Space travel currently costs a lot - I maintain that this is due to lack of expertise. If there is a sufficient profit motive in space, companies will find ways to do things cheaper and faster and, arguably, better (not being a terrible believer in an unregulated market, this last point is debatable). Prove that we can go get to the money, and people will go get it.
Which brings me to my last point - spending philosophy. A lot of people decry spending on the space program, arguing that the greatest benefits have come from near-Earth satellites and such; and besides, they say, aren't there better things to spend the money on? This is true, in a sense. But, I, for one, would rather spend another billion dollars on the space program, on research and development, than on a new B2 bomber that doesn't work the way it should and whose role as a long-range strategic bomber was obviated by the end of the Cold War. Finding a more worthy cause - education, health care, welfare - does not eliminate the need to spend on less worthy causes. The point is, we don't know yet what we might find worthy in space. It is a money sink until we find that. I think it is worth examining - with plans like reuseable launch vehicles and space elevators and Lagrange-point stations, we have a number of ways to lower the financial barriers to space.
I am not generally one to talk so, but I think we have a responsibility to future generations and to our own sense of intellectual completeness to reach into space. The cost will be mitigated over time. The benefits could be grand. The investment will surely be prohibitive. The continued and future examination and implementation of space travel depend on a long-term view of the investment, a willingness to look for opportunities, and a certain modicum of childlike wonder and hope. Space is great. It's just hard to get to right now.