Startram — Maglev Train To Low Earth Orbit

Zothecula writes "Getting into space is one of the harder tasks to be taken on by humanity. The present cost of inserting a kilogram of cargo by rocket into Low Earth Orbit (LEO) is about US$10,000. A manned launch to LEO costs about $100,000 per kilogram of passenger. But who says we have to reach orbit by means of rocket propulsion alone? Instead, imagine sitting back in a comfortable magnetic levitation train and taking a train ride into orbit."

Hmmm, 1600 km of superconductors...

[hbar squared]

" there is a superconducting cable on the ground carrying 200 million amperes, and a superconducting cable in the launch tube carrying 20 million amperes, at an altitude of 20 km there will be a levitating force of about 4 tons per meter of cable length"

That works out to an energy density of (mgh)=1.5e9 J/m. Multiply that by 1600 km, and you get 2.5e15 J, or half a megaton, equivalent to the yield of a small hydrogen bomb. Anyone ever see a superconducting magnet quench?

cargo version much more practical

[bcrowell]

The thing that makes this such a ridiculous engineering project is the requirement to carry humans, who can't be subjected to more than about 3 g's. The length of the track is inversely proportional to the acceleration, so if you're sending up steel I-beams that can withstand 3000 g's, you can shorten the track to 1 mile rather than 1000 miles. Tanks of water and rocket fuel can also be subjected to a lot more than 3 g's.

Re:Fucking magnets

[mcgrew]

I know that a sample of one is insignifigant, but my dad was a lineman working with voltages up to 90k. He could not wear a wristwatch unless it was completely made of non-ferrous material, because when he put it on after work, an hour later it stopped. Apparently his hemoglobin was magnetized. Yet he's now 80 and still in good health.

I wouldn't worry about the magnetic fields. Apparently having your blood megnetized is harmless.

Of course, the fact that his uncle started smoking cigarettes at age 12, quit at age 82 and lived ten more years illustrates that a sample of one is indeed insignifigant and perhaps meaningless. Me, I'd risk magnetic blood for a chance to go to outer space anyway, as I have half of dad's genes.

Re:Fucking magnets

[jandrese]

When someone proposes a gigantic megaproject like this and says that it would be technologically possible with todays materials, I always assume that they have oversimplified many parts of the design and that there are serious fundamental problems with the approach. This has been a pretty safe bet so far, and I don't think I'm going to be wrong here.

Here's a question: When you are accelerating a multi-ton mass at 3G up to the top of a tube that is 24 times higher than the highest skyscraper in the world, how do you keep it from buckling under the force? Don't assume that the designers have thought about stuff like this, because most of the time they have not. They just worked out the basics on the back of a cocktail napkin and got all excited.

Space elevator enthusiasts tend to be really bad about this. They're dreamers, not engineers.