Comments on: Space Towers

By: anon

anon — Sat, 20 Jun 2009 15:30:54 +0000

As a chemist, I see a serious flaw in this proposal. Mainly, it requires a lot of helium. Since Earth’s gravity doesn’t capture helium, we have a very limited quantity available on Earth.

We can harvest some helium from the Sun. Yes, it’s quite hot, but we’d go there at night time.

By: Tim Tyler

Tim Tyler — Sat, 20 Jun 2009 10:46:37 +0000

More uncritical coverage:

http://scienceblogs.com/principles/2009/06/inflatable_space_elevator_eh.php

To reiterate, the idea makes no sense, because of the wind.

By: Paul Crowley

Paul Crowley — Wed, 17 Jun 2009 12:39:09 +0000

Such launch devices will pay their way in reducing existential risk if they can reduce the cost of global warming mitigation strategies like the Angel fleet.

By: Jay

Jay — Tue, 16 Jun 2009 15:47:47 +0000

As a chemist, I see a serious flaw in this proposal. Mainly, it requires a lot of helium. Since Earth’s gravity doesn’t capture helium, we have a very limited quantity available on Earth. Helium also diffuses rather quickly through many materials (you may have noticed that helium balloons tend to shrink in a few days), so constant replenishment would be needed. I haven’t done the math (and couldn’t, without estimates of the surface area, thickness, and relevant helium diffusion constants of the materials of choice), but I seriously doubt that this is a practical proposal.

By: John Maxwell IV

John Maxwell IV — Mon, 15 Jun 2009 04:46:10 +0000

>What likely risks can you think of that space colonies would be safe against, but sealed deep mines on Earth wouldn’t?

That’s a good point. I suppose that sealed deep mines could use geothermal energy. But you might be stuck in the mine for a while in the event of a catastrophe.

Do you know of anyone working on the problem of surviving a long time in a sealed deep mine?

By: Nick Tarleton

Nick Tarleton — Sun, 14 Jun 2009 17:56:13 +0000

What likely risks can you think of that space colonies would be safe against, but sealed deep mines on Earth wouldn’t?

By: John Maxwell IV

John Maxwell IV — Sun, 14 Jun 2009 04:09:37 +0000

>We aren’t remotely close enough to a low enough cost of getting into space to kick off a substantial space economy. So the best way to get to that point is to simply grow the world economy; investments now in space activities that don’t pay their way hinders that goal.

OK, I’ll tentatively take your word for this because you’re an economist. But I’ve got a question: does the sector of the economy matter? If video game sales go up does that help spaceflight?

It seems to me that this question is quite complicated. Another aspect of things is how reasonable the assumption that man-hours convert into research results at a constant rate is.

By: Robin Hanson

Robin Hanson — Sat, 13 Jun 2009 21:20:32 +0000

I just added to the post.

By: Roko

Roko — Sat, 13 Jun 2009 21:20:02 +0000

> We aren’t remotely close enough to a low enough cost of getting into space to kick off a substantial space economy. So the best way to get to that point is to simply grow the world economy; investments now in space activities that don’t pay their way hinders that goal.

What $ per kilogram to orbit do you think we need to get to?

By: Robin Hanson

Robin Hanson — Sat, 13 Jun 2009 14:28:17 +0000

We aren’t remotely close enough to a low enough cost of getting into space to kick off a substantial space economy. So the best way to get to that point is to simply grow the world economy; investments now in space activities that don’t pay their way hinders that goal.