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Going To Mars Via the Moon (mit.edu)
An anonymous reader writes: Getting anywhere in space is a difficult proposition — at least, if you want to get there in a timely manner. Rocket propulsion requires combustion mass. The more mass you take, the more you need. A team at MIT has found that establishing fuel-generating infrastructure on the Moon could reduce launch mass for missions to Mars by up to 68%. "They found the most mass-efficient path involves launching a crew from Earth with just enough fuel to get into orbit around the Earth. A fuel-producing plant on the surface of the moon would then launch tankers of fuel into space, where they would enter gravitational orbit. The tankers would eventually be picked up by the Mars-bound crew (PDF), which would then head to a nearby fueling station to gas up before ultimately heading to Mars." The technology to make this happen is not difficult to build; it just requires a lot of money. Once it's in place, it'll cut down on expensive launch costs. As the commercial space industry gets going and launches happen more often, such an investment starts to make more and more sense.
the rest is just commentary.
So is Space X. or did you not know that space X primary funding comes from doing launches for NASA?
NASA's budget is such a mess because NASA was always required to give no bid contracts for the big jobs to certain companies in certain states. That was congress's doing. Give NASA a fixed budget and let them decide where to procure items and the costs of space travel for NASA would have fallen sharply.
i thought once I was found, but it was only a dream.
There's always dull people on stories like these. You boring bastards are always there holding the doers back with your pathetic can't do attitude.
Well, if you want to send people anywhere else the moon is an excellent place to try things out because if it goes pear shaped you are only a couple of days away from Earth. Once you are confident of the technologies working on the Moon then you can go forward to Mars with more confidence because Mars isn't such an extreme environment. If you go straight to Mars and something goes wrong it's at least a six month journey back home. That's a long flight in an emergency.
Electromagnetic catapults are overkill for small amounts of mass launch from the Moon. If you need a million tons a year, they are great.
For small amounts, a centrifugal catapult works fine. Rotor arm of high strength material, electric motor, and solar arrays to power it. The Moon is small enough that you can reach orbit velocity with ordinary materials. If you have two rotors, you can regeneratively slow down one to reload while spinning up the other, with little energy wasted.
Math on rotor arm:
Lunar orbit velocity + a bit so it misses mountains and can be collected = 1700 m/s.
Assume 1000 g's at the rotor tip. You are launching rock, it doesn't care. Acceleration = v^2/r. Solving for r we get 290 meter radius. Acceleration varies linearly from center to tip, so is 500 g's average x 290 meters = 144.5 g-km.
High strength carbon fiber has a characteristic strength of 361 g-km, but you don't design to ultimate strength. A reasonable value is 150 g-km, giving a rotor taper of about 3, and mass ratio of 6 because it has two arms. You want the rotor to be balanced so it doesn't jerk the axle around, which means you also throw a rock backwards into a hill. That's inefficient, but there is no lack of rocks.
A modern solar array can supply the 1.44 MJ/kg to launch it's own mass of rock in 2.25 hours. Since we throw an equal mass into a hill, we get 4.5 hours, and allowing for inefficiencies, let's assume 6 hours. The Sun is shining half the time, and a solar array lasts ~15 years in space. So a solar array can power launching 11,000 times it's own weight before it wears out. Add whatever the rotors, motors, and other infrastructure you need (rock loaders and gatherers) and you are till way ahead.