Comments on: Tubes? In spaaaaaace?

Question: Tubes? In spaaaaaace?

punkbitch — Thu, 20 Jan 2005 17:29:29 -0800

What would happen if someone were to build a tunnel or tube into space? (Description inside...)

What I'm imagining is a collapsible tube made out of an ultra-strong material that a rocket would "erect into space." Huh? Well, what if a rocket, attached to this tube material (which could collapse onto itself like those collapsable cups) blasted off into space.

Basically . . . if there were a tube that connected the ground with outerspace . . .what properties would it exhibit? Would the atmosphere remain the same inside the tube as it is outside? Would this create a vacuum? Could we throw our garbage into orbit . . .or better . . . out of orbit? Thanks Mefites!

By: odinsdream

odinsdream — Thu, 20 Jan 2005 17:38:56 -0800

The atmosphere would stay exactly the same as it was. Up near where the atmosphere thins, it would be thinning in the tube. If you evacuated all the atmosphere in the tube, well, that would make it a vaccum. Same with gravity. What's the confusing part, here?

By: odinsdream

odinsdream — Thu, 20 Jan 2005 17:42:05 -0800

Think of putting a straw in your glass of water. The water inside is the same as the water outside, with the exception of that miniscus.

By: punkbitch

punkbitch — Thu, 20 Jan 2005 17:46:30 -0800

Aw Christ. I can't believe I'm that conceptually challenged. Thanks.

By: zanni

zanni — Thu, 20 Jan 2005 17:49:01 -0800

odinsdream is right. Consider the analogy of a goldfish extending a tube into the "space" (air) above his fishbowl. It wouldn't draw air down into the fishbowl or expel water up into "space." You'd just have a tube (assuming you don't seal it at the bottom). It might be handy to throw your garbage into space, but you cuuldn't just toss it in the tube, it'd have to be propelled up the tube.

You might be interested in beanstalks which are giant elevators into space. You attach a long, very strong cable to the Earth and extend it into space (actually, you start in orbit and extend in both directions simultaneously). Then you can attach cars to the cable and ride them up and down very inexpensively compared to rocket flight.

Arthur C. Clarke wrote a novel about beanstalks. So did Charles Sheffield.

By: mr_roboto

mr_roboto — Thu, 20 Jan 2005 18:07:58 -0800

If it were sealed to the ground (and perfectly sealed at all other points), however, it would contain a vacuum. The rocket would be pulling a vacuum in the tube as it is extended, and if it were opened at the far point (in space, after being extended) the interior would equilibrate to the pressure of space (near vacuum).

Unless the tube had a tiny diameter, the rocket would require a ridiculous amount of force to pull this vacuum.

By: MLIS

MLIS — Thu, 20 Jan 2005 18:34:54 -0800

Space Elevators article (via DefenseTech.org). Also see the Space Elevator Reference blog.

By: ikkyu2

ikkyu2 — Fri, 21 Jan 2005 03:57:46 -0800

The interesting thing about these Beanstalks is that, once you erect them at a suitable place (say, the equator), they hold themselves up. That's very cool.

They also appear in novels by Robert Heinlein and Kim Stanley Robinson, to name two.

By: ikkyu2

ikkyu2 — Fri, 21 Jan 2005 10:44:31 -0800

I've been thinking more about this, and I am wondering whether Coriolis force wouldn't produce a whirling vortex of air inside the tube, assuming the tube was *not* erected at the equator. I kind of think it might, given the right size tube.

But a cleverer person than I would be required to do the math.

By: tomble

tomble — Fri, 21 Jan 2005 14:38:32 -0800

Probably not. The Coriolis effect isn't really that strong unless the theoretical tube was massive.

Of course, if that happened, we could harness the power in it like this gigantic tube.

By: ikkyu2

ikkyu2 — Fri, 21 Jan 2005 15:52:13 -0800

Well, the Coriolis effect is pretty weak, but there'd be nothing else inside the tube to oppose it.

I like your gigantic tube, tomble.