Space Elevators: Low Cost Ticket to GEO?

Crocuta writes "The current issue of Science News features a cover story that discusses the current developments in space elevator technology. NASA has been working on such devices for many years, but private companies such as Highlift Systems are now jumping on the space elevator bandwagon, no doubt seeing the huge potential profit in a low cost per pound delivery system. PhysicsWeb has a somewhat older, but much more technical article on the formation and structure of the carbon nanotubes that form the basis of the proposed tether cables. With a development like this, we could shoot entire boy bands into space and make the world a better place."

Comments

Re:ok but

[Nintendork]

This story is a repeat that I've seen at least one other time here on /.. If I recall correctly, the cable is very unlikely to snap, but if a terrorist were to break it, the cable would fall to the ocean and there wouldn't be any devastating impact.

Re:I've said it before

[sketerpot]

The tower shouldn't be too much more expensive to maintain than the NASA Shuttle fleet, in my estimation. The ribbon itsself would be very strong and placed in an area with very mild weather. And it would manage to lift about a ton of cargo to space every day!

That would still be very expensive, but immensely less expensive than using the current methods of reaching orbit for comparable amounts of cargo.

Of course, my estimates are open to dispute, and I could be wrong. But I don't care: the space elevator is cool!

Re:Oh great, one more reason for Bush to intervene

[Docrates]

After a cruise through tropical waters, you arrive at a large, anchored platform in the middle of the Pacific Ocean

The very first few lines of the article. The anchor would be a modified oiling platform, not a tower in ecuadro, Brasil or Peru (which, BTW, are NOT anti-american). This platforms are located outside any countries jurisdiction.

More info

[Truckle]

Here are some more links to info on our very own Slashdot:

Here
Here..
Here..
and Here

Really good NASA article

[Tidan]

Here's a nice sized (15MB) report done by NASA. They talk about all sorts of problems that need to be worked out to make get this project off the ground http://www.niac.usra.edu/files/studies/final_repor t/pdf/472Edwards.pdf

Re:Riiiiight...

[unicron]

Tits are nice, but I'm all about an oxygen supply.

Short term option

[alwayslurking]

You don't need to tether the end, you can still get some very healthy benefits with a partial elevator. Deals with a lot of the security issues too. Cargo craft only need to fly to the low end and ride the rotation to the top where they can slingshot off. Using the Earth's magnetic field and solar power means it's self-stabilising too. More detail and better writing at; Free David Brin Short Story

Re:another use for it...

[slide-rule]

Just a minor clarification on the parent...

The "slingshot effect" is only useful for trajectory changes. [cut] Due to conservation of energy, when you approach a planet and slingshot away from it, you end up with the same velocity on the way out as the way in.

This is correct enough, but for those who haven't taken an orbital mechanics class, I thought I'd chip in a little bit more info. The 'slingshot' effect seems to work since you (the object) is changing frames of reference into- and out of the planet being used. (The other frame being with respect to the sun.) Additionally, you have to do the approach from the 'backside' so the planet pulls you forward on your way by (assuming you want to gain speed; otherwise enter on the front-side to slow down).

Once you leave the sphere of influence of the planet itself though, and are only under the dominant effect of the sun (i.e., changed frames of reference) you have changed net velocity (speed as well as direction).

Re:another use for it...

[Soft]

The "slingshot effect" is only useful for trajectory changes. It allows one to save fuel when changing directions. Due to conservation of energy, when you approach a planet and slingshot away from it, you end up with the same velocity on the way out as the way in. You will accelerate as you approach a planet, but you will decelerate the same amount on the way out.

All true, but you missed two points:

• in a slingshot maneuver you cannot, indeed, gain velocity relative the planet you approach; you can (and space probes do) gain velocity relative to the Sun, since said planet is moving with respect to the latter;
• the original poster, I think, did not have a gravitational slingshot in mind, but the effect you would get if the top of the elevator were above GEO, you could launch objects that way.

Re:another use for it...

[ENOENT]

BZZT!!! No, you're forgetting that the planet has its own velocity, which a spacecraft can steal. When a spacecraft slinshots around a planet, its velocity on the way out is the same as its velocity on the way in, but this the the velocity RELATIVE TO THE PLANET. If the spacecraft approaches the planet head-on, and does a 180 degree slingshot around the planet, then (ideally) its final velocity RELATIVE TO THE SUN is equivalent to its initial velocity plus two times the planet's orbital velocity. Energy is conserved, because the energy gained by the spacecraft is stolen from the planet.

Highlift Systems FAQ

[TheOnlyCoolTim]

Will the wire generate power?

Yes, but only in the milliwatts.

Tim

Re:Free Electricity

[deander2]

Actually, the "free" energy is taken directly from the rotational inertia of the earth itself. So this would slightly increase the length of our day, but only VERY VERY slightly. When you consider the mass of the earth and how fast it spins, you could power all of humanity for much longer then you could imagine before the earth's day was noticably different.

Also, the earth's rotational speed changes gradually anyway...

Re:Free Electricity

[freuddot]

Useless.

You'd have the same problem as with any other potential field :

You get access to particle X at extremity X0 of some energy potential field Y, compared to extermity X1 .

However, in order to use this energy, you have to put something (a wire) between X0 and X1(the two ends of your elevator). This something(wire) however will receive the same field effect, and will cost you the same exact energy amount.

In plain terms, you've got to ship back those electrons to the top of the wire, to get electricity. The more easily they came down, the harder it gets to send them back.

Otherwise, you could do the same in airplanes. Airplanes, while travelling trough the magnetic field of earth build a good potential difference between their wing tips. If you try to use it, though, the wire you put will build the same voltage, preventing you from using this energy.

BTW, that's also why you can't shield gravity.

HTH

J.