[ot] Mars colonization

[Wil]

They've already looked into the possibility that the cable will generate electricity within the atmosphere as it orbits. That could be put to good use.

As for failsafes, I can think of so many that it becomes trivial to insure the cable doesn't hurt anything should it fall. Any kind of failsafe built into the cable could definitely use gross variations in the electrical field to trigger severing devices - sensors that detect variations in velocity could also work. If the cable were to snap, its velocity would change drastically, triggering explosives or whatever to sever the cable into small segments. Since sections of the cable are at set altitudes, barometric pressure sensors could trigger the sections to sever. For the sections that are in vacuum, any amount of atmospheric pressure would make them go off. Temperature changes could set them off as well.

 

[Umbran]

As for failsafes, I can think of so many that it becomes trivial to insure the cable doesn't hurt anything should it fall.

Now. boys and girls, let's just imagine what happens if one of these failsafes ever misfires. An let us note that if you put anything on the cable that is actually designed to destroy it, that makes terrorist action all the more easy...

 

[tleilaxu]

personally, i think Wil is being a bit dismissive about the risks of a cable.

paraphrasing: That'd never happen, and if it did the cable wouldn't hurt anything!

The biggest problem with the cable (besides the unknown risks of it falling) is that it centralizes so much power. All of a sudden control of the cable and access to the cable become the biggest sources of conflict on the planet, not to mention such a centralized nexus becomes a huge target.

Here's a lesson from history: If humans are clever enough to build it, they're clever enough to destroy it

 

[Umbran]

The biggest problem with the cable (besides the unknown risks of it falling) is that it centralizes so much power.

Yep. It's rather large bunch of eggs to be keeping in one basket. When in doubt, don't centralize into something quite that large, complicated, and expensive. It'll either break, or get broken. Murphy's Law.

Btw, I don't know if this has gotten mentioned in the thread, but if you're interested in a quick overview of more exotic technologies that can be used to lift people into orbit, there's a book by Robert L Forward that covers many of them - Indistinguishible from Magic

 

[Kilmore]

From tleilaxu
"personally, i think we should practice putting some asteroids into earth orbit before we start building space elevators."

Personally, I hope they practice moving asteroids BEFORE they bring them to earth orbit!

Also from tleilaxu
"Actually, when you think about it monkeys and dogs were in space before homo sapien sapiens. I gues they've come up with the ultimate survival instinct: make friends with the hairless monkeys."

Um, that didn't work out so well for the dog...

As far as it falling to earth goes, there's a few things I need to know before I can make an opinion on it. How much is the snapback force expected to be when it loses tension on the top? How much is the atmosphere expected to brake the tether as it drops to the earth?

At any rate, the space elevator is only one way to get off the planet. Personally, I think electromagnetics is another promising technology to get us off the ground.

 

[tleilaxu]

I think it may have something to do with ions but i'm not sure:

Have you heard about these ultralight flying things that don't need fuel? I saw one on tv. The bottom of it focuses light or something and goes *snap* *snap* *snap* *snap*, and with each snap there is a burst of light and up it goes. Anyone know what I am talking about?

 

[Umbran]

Yep. I think I know of what you speak.

Take a frisbee-ish, ufo-looking disk. Mirror the underside. Give it a high rate of spin for gyroscopic stablization. Fire a powerful pulsed laser into it's underside.

The laser strikes the underside, and is refocused upon a point just under the disk. The air there is instantly superheated, and rapidly expands, lifting the disk. The snap and flash of light are a miniture thunderclap, and an ionization flash from the heated gas.

 

[tleilaxu]

sounds right. What if we made a really huge version of that? That would be a pretty cool way to get to space...

 

[s/LaSH]

This disk idea is hideously unaerodynamic... so tape a cone to the top, and mount the gryo lens separately so your passengers don't see the same piece of scenery three thousand times each second. Oh, and you'd have to use some pretty lightweight tech to make the thrust high enough... but that's what these molecular technologies we've been discussing are for in the first place, so no problems there.

Now all that's needed is a good high-power laser, and I know the US military is working on those... some quick stats: they've currently put US$50 million into getting a 25-kilowatt solid state laser by 2004, with the aim of a 100KW laser by 2010. The most powerful laser in existance is apparently 10KW. Now, when a 25KW laser can put holes in armour plate from miles away, by the time a laser launch system becomes a possibility it could well be very practical.

Of course, the real use of lasers would be in deep-space acceleration; it's like solar sails, only you're not relying on the sun, you're relying on a titanic satellite in Earth's orbit pumping out more energy than you could imagine. Probably with fusion or a planetary magnetic field generator.

Lasers are cool. And I hear that Defence Secretary Rumsfeld thinks so too.

 

[tleilaxu]

my old college house mate does lasers at UC-Berkeley

we always used to joke with him:
"hey baby, would you like to see my laser?"