Space Elevators Maybe Closer To Reality Than Imagined

Spacedaily ^ | 7/22/03 | Richard Perry

[Brett66]

You misunderstand me. Our future in space will be a hundred times greater than what NASA will accomplish by themselves. Private enterprise is awakening to the possibilities of commercial space. We'll have hotels on the moon in a few decades and NASA will have no role in that development.

[Lawgvr1955]

Can you imagine listening to Muzac for the time it takes to ride a 90,000 km elevator.? Painful

[Arkie2]

Yeah, that was a pretty stupid song. The elevator to space, however, is a legitimate idea.

[6ppc]

The whole idea is pretty much stupid.

Wrong. If the materials are available this is the cheapest way to get to orbit. If we can get out of the gravity well at low cost, the entire solar system is available for exploitation.

[6ppc]

this tower will be exceeding the speed of sound as it rotates through the atomsphere?

It just so happens it will be moving at the same speed as the surface of the earth.

[Arkie2]

Hmm. Monday night football coming to a planet near you. I see revenue potential like you wouldn't believe!

[BlazingArizona]

Hmm, with all the talk of avoid natural disaster I think they should build it right here in Tucson. No hurricanes, no tornados, no earth quakes, no volcanos, we get "flood" but compared to what the rest of the world considers a flood they're nothing.

The only problem with that scenario would be the high cost of moving Tucson to the equator. But then again if we did that, Tucson could be manned by Indians like everything else, substantially reducing the cost of building the elevator.

[Arkie2]

Do elevators move slower and require more energy in Reykjavik than in Brazil? Just wondered.

[only1percent]

Private enterprise is awakening to the possibilities of commercial space.

I deal regularly with the aerospace industry and, to be honest, I don't see anyone talking about anything except ways to build and launch satellites cheaper and with higher-power lower-interference frequencies. That's not trivial, of course, but I don't see much more.

[The Louiswu]

"Stairway to heaven? The whole idea is pretty much stupid."

So was flying, but look how that turned out.

[Arkie2]

Your time horizon is too short. Nothing talked about here will take place in the near future. None of this stuff will be commercially viable for a couple decades but it's the future of space exploration.

[Brett66]

That's old aerospace, here's an example of new aerospace:

SpaceX

XCOR

Canadian Arrow

Scaled composites

X-Prize

[edwin hubble]

"Do elevators move slower and require more energy in Reykjavik than in Brazil? Just wondered. "

Because of Earth's rotation there is lower net 'gravity' at the equator than at the pole. Also, the equator is farther from the center than the pole, due to the shape of the Earth.

[Museum Twenty]

bfl

[Arkie2]

The most exciting thing going on right now has nothing to do with space elevators. It's the marriage of a small scale fission reactor with an ion propulsion system. This has potential within this decade if the greens don't kill the launch of the nuclear power source. Solar exploration would move into an entirely different plane.

[Arkie2]

So your answer would be yes?

[King Prout]

don't these things by definition HAVE TO BE on the Equator?

[dr_lew]

The idea is impossible anyway. There is nothing 'holding' up a satellite in the first place, other than two counter-posing forces--1. The centrifugal force caused by the speed and mass of the satellite, which tries to fling it away the Earth, and 2. The centripetal force of the Earth's gravity, trying to pull the satellite towards the planet. That's it, just 2 forces, a push and a pull, balanced for a given set of paramaters.

Don't forget the Coriolis force due to the motion of the elevator. The elevator has to gain velocity of revolution as it rises, so some ( considerable ) force must act perpendicularly to the "tape" to provide it.

In fact consider this: Since the geosynchronous height is about 6.6 earth radii, the velocity is about 6.6 times what it is on the surface of the earth. On the other hand, in LEO the orbital period is about 90 min., or about 16 times that same speed. So we must have some extra source of perpendicular acceleration to get up to 6.6/16 or about 40% of LEO orbital speed. So how about that?

If you hook a cable to a satellite, regardless of the satellite's mass, it will move towards the Earth since you are changing the mass/speed balance that defined the original orbit.

The anchor has to be above the geosynchronous point, then its speed of revolution is greater than it would be as a free satellite, and the downward pull of the tape, or whatever, provides the extra centripetal force to balance the geosynchronous centrifugal force. Think about it.

Nevertheless, I think you are on the right side. The idea is ridiculously impracticable.

[dr_lew]

You misunderstand me.

Magua say he understand English very well.