Re:Where is my von Braun wheel?
by PaulHoule on Thursday July 03, 2025 @01:05PM
(#44457116)
The image of the really big mass driver that looks like a train you get from O’Neill or Heinlein is obsolete.
The US Navy built a 2.5km/s railgun you could fit on a ship. A 3.5 km/s coilgun has to look like the Paris gun to be practical and be able to shoot at a high elevation to hit Earth-Moon L1/L2 or near-Earth space. A railroad car worth of material per day in 1kg or so increments seems plausible. A radiation shield for a deep space station or a simulated asteroid to test mining and manufacturing technology might compete with terrestrial materials.
O’Neill’s students never came up with believable catcher and I’ve yet to see one I like. I guess you could get to LEO if you could aerobrake but it looks tough because the outer atmosphere is always changing and a wild shot could trash your target, talk about a space junk problem.
The moon has at best a large glacier on it and my guess is Lunarians, if they could vote, would not want to export a gram of it but rather incorporate it into a circular economy.
The US Navy built a 2.5km/s railgun you could fit on a ship. A 3.5 km/s coilgun has to look like the Paris gun to be practical and be able to shoot at a high elevation to hit Earth-Moon L1/L2 or near-Earth space. A railroad car worth of material per day in 1kg or so increments seems plausible. A radiation shield for a deep space station or a simulated asteroid to test mining and manufacturing technology might compete with terrestrial materials.
O’Neill’s students never came up with believable catcher and I’ve yet to see one I like. I guess you could get to LEO if you could aerobrake but it looks tough because the outer atmosphere is always changing and a wild shot could trash your target, talk about a space junk problem.
The moon has at best a large glacier on it and my guess is Lunarians, if they could vote, would not want to export a gram of it but rather incorporate it into a circular economy.