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Gigantic Air Gun To Blast Cargo Into Orbit
Hugh Pickens writes: "The New Scientist reports that with a hat tip to Jules Verne's From the Earth to the Moon , physicist John Hunter has outlined the design of a gigantic gun that could slash the cost of putting cargo into orbit. At the Space Investment Summit in Boston last week, Hunter described the design for a 1.1-kilometer-long gun that he says could launch 450-kilogram payloads at 6 kilometers per second. A small rocket engine would then boost the projectile into low-Earth orbit. The gun would cost $500 million to build, says Hunter, but individual launch costs would be lower than current methods. 'We think it's at least a factor of 10 cheaper than anything else,' Hunter says. The gun is based on the SHARP (Super High Altitude Research Project) light gas gun Hunter helped to build in the 1990s while at the Lawrence Livermore National Laboratory (LLNL) in California. With a barrel 47 meters long, it used compressed hydrogen gas to fire projectiles weighing a few kilograms at speeds of up to 3 kilometers per second."
If you RTA (yes I know, not likely), you'll see that they acknowledge this issue, their intent is to use this for robust cargo only (rocket fuel is given as an example, not e.g. satellites or humans)
Send up consumables, for sure. Fuel, water, compressed air, freeze-dried food, etc. Even if just used for that, this is not a bad plan. There's no rule that says you have to use only ONE method to get stuff off-planet.
You'll need conventional lift to get the tools up into space to build an orbital mining facility. This air-gun can be used to lift all the materials that those tools will use to build the mining facility and fuel for the crafts that will go get the asteroids and coax them back. But once that's done, we ought not need the air gun nearly as much or at all.
Depends on what you're planning, really. If your goal is to actually spread the human race out from Earth, this could be used long-term. Just keep sending up loads of water and compressed air, etc., for however long you can afford to do so. Keep the stuff in a stable orbit and just leave it there for however long you need (years, no problem, really). Once you're ready to use it (in LEO, at a Lagrange point, on the Moon, Mars, etc), move it to where you need it, as the most costly part of getting it into orbit has already been done.
That's one of the biggest problems with the U.S. space programs, the lack of long-term thinking and planning (and funding for a long-term strategy).
I've heard it argued by folks who sounded like they knew their stuff that it's much cheaper to do it by dragging in asteroids (maybe one with a cubic mile of ice in it) than to shoot it up from earth. I admit, I haven't seen the numbers.
Considering we just hit the Moon to try to figure out how much water ice is there, it seems unlikely that we have any good ideas on which asteroids have water ice in them, much less the ability to bring them to where we need them (yet). That's more the type of project I'd expect a few decades _after_ we do what this project is talking about. All in good time, my friend...