Slashdot Mirror
Nautilus-X: the Space Station With Rockets
astroengine writes "So we have a space station, now what? We've heard some rather outlandish ideas, but this is one concept a research group in NASA is taking seriously. By retrofitting the ISS with rockets, Nautilus-X will act as an interplanetary space station of sorts, including room for 6 astronauts, an artificial gravity ring, inflatable habitats and docking for exploration spaceships. When can we take a luxury cruise to Mars? 2020 by the project's estimate. It all sounds very 2001, but the projected costs of retrofitting the space station seem a little on the low side."
Hahah, alright so. You construct an 11km high tower/launch ramp, a compressive tower the same as cell towers as a truss of smaller elements. A reasonable height-to-base ratiomight be 20:1. So a 10 km tower would have 3 base points 0.5 km apart, assuming you have a triangular cross section for the tower as a whole.
Each principal column would in turn be a truss with 3 sub-columns spaced 25 meters apart, which in turn are made of tertiary columns 1.2 meters apart and 0.06 meters in diameter each. The tertiary columns have a wall thickness of 0.03 meters. This puts you above the denser elements of the atmosphere. Its not nearly as hard as it seems, Frank Lloyd Wright designed mile-high skyscrapers back in the 30's.
Then you run maglev/railgun type vacuum tubes up the length of it, therefore using extremely cheap electrical energy to power the vessel through the first stage, which I think should put the ship into LEO at 7g, althoughyou'd probably still need a booster stage.
If you could launch at 10000 ft above sea level, you could reduce your velocity change to get into orbit by approx. 250 m/s. However, you need about 8000 m/s to get into orbit. A 3% improvement, which would actually be a serious improvement. A RL-10A has an Isp of about 450 seconds; thus, exhaust velocity Ve is about 4400 km/sec. Structure and payload mass fraction is exp[deltaV/Ve]; a RL-10A powered vehicle could achieve a maxium amount of structure plus payload to 8km/sec of 16.3%. Typically about 5% of this is actually payload. A 3% decrease in delta-V to orbit increases this to 17.3%. This increases the *payload* to 6% of the gross lift-off mass -- a 20% increase in payload.
Imagine the benefits of launching higher and a lot faster.
This has the effect of vastly reducing the cost to get to LEO and from there to proper orbit and eventually escape; if it was as cheap to get to orbit as it is to cross oceans, we'd already be on Mars.
So lets talk mineral wealth. The most detailed study of an asteroid, Eros, collected by NEAR shows that it contains precious metals worth at least $20 trillion. If Eros is typical of stony meteorites, then it contains about 3% metal. With the known abundance's of metals in meteorites, even a very cautious estimate suggests 20,000 million tonnes of aluminium along with similar amounts of gold, platinum and other rarer metals.
That is just in one asteroid and not a very large one at that. There are thousands of asteroids out there.
So once you make it economical to get up there, you need to build out an infrastructure. There are lots of theories on how to do this by aseroid resource extraction, I'm wavering towards the "rubble pile" asteroids which come pre-demolished, I can go into more detail if you like.
Let's be clear though, unless a launch tower would drastically lower costs to space, the initial buildout has to be for space and by space. Then once orbital manufacture has reached a sufficiently advanced level, you can send manufactured goods, worth many times their wieght in gold, straight back to earth markets.
/borrowed from many sources, I haven't the time to do the maths right now.