What is Space elevator?

Question

What is it?

Answer 1

A Space Elevator is significantly less interesting than fictional accounts represent. It's simply a very long, very strong ribbon that is attached to the earth and extends outward far enough that inertia can overcome gravity. Robotic "lifters" climb this ribbon with cargo attached to them. Commercial ventures working on space elevators plan to carry from 7 to 100 tons of cargo per trip, and can makes those trips weekly or even daily.

Unlike rockets, these lifters will not have to carry their own fuel. Attached to them will be massive photo-voltaic cells (solar cells). Energy to power the system will be "beamed" to the lifter using lasers from the ground. By not having to carry it's own fuel, though slower, the process will be vastly more efficient than using rockets. Initial estimates suggest a price of $400/lb (657 euro/kg). At that price, pre-university students could even send up science packages with the proceeds from a weekend car-wash.

The way a space elevator works is like a ball on a string. Hold the string over your head and spin your hand. The ball overcomes the pull of gravity and the string gets pulled taut. The Space Elevator works the same way. A 62,000 mile (100000km) long string or ribbon is attached to the earth which spins. A small satellite acts as a counterweight at the end and the centrifugal effect pulls the string a little bit harder than gravity does.

This process results in incredibly strong forces pulling in both directions with the maximum pull being just above geosynchronous orbit at 22,800 miles. With a ribbon made out of Spectra (tm) the mass required to hold itself up would result in over 100 heavy lift rocket launches just to get the material in orbit to assemble and deploy. The cost involved would be phenominal and not practical.

A developing material, "Carbon Nanotubes", have the potential to make it financially feasable. To keep the number of launces down to a reasonable number, a ribbon capable of supporting one ton of cargo with a small safety margin would have to be able to withstand at least 60Gpa (gigapascals) of force. Carbon Nanotubes have been measured with a strength as high as 100Gpa, but have not been able to show that strength when assembled into any sort of rope, ribbon, or other structure. Further development does, however, look promising.

A lunar based space elevator, however, could be done today. The gravitational forces involved are much lower. A lunar space elevator (LSE) would be held in place by balancing the pulls of gravity from the moon with the pull from earth. This would require a ribbon of material with the strength of Spectra(tm) or Dyneema(tm) and would be roughly 150,000 miles long. The biggest problem with the LSE is that in order for it to be cost effective, there has to be a customer wanting to transfer cargo. News from the LiftPort Group on April 7th, 2007 suggested that there is indeed a customer who is interested in working on a LSE to support a moon based manned observatory they're constructing.

Answer 2

A space elevator is a new proposed way of getting payloads into Earth orbit. Rather than using a rocket, the idea is to build a huge cable (probably out of carbon nanotubes or something similar) which is anchored at the surface of the Earth and stretches out to just past geosynchronous orbit, where it is attached to an asteroid or a space station as a counterweight. If the counterweight is massive enough, the rotation of the Earth will cause enough centrifugal force that it will pull up the rest of the cable and stay in place without the use of rockets. Once this has been done, we can send specially built machines up the cable to carry payloads into space. Some scientists believe that space elevators might be able to cut the costs of delivering material into space to up to 50 times less than it currently is ($4000 per kilogram by rocket down to $80 per kilogram by space elevator).

You can read more about space elevators here:
http://en.wikipedia.org/wiki/Space_elevator
http://www.space.com/businesstechnology/technology/space_elevator_020327-1.html
http://www.elevator2010.org/faq.html

Answer 3

Also called a bean stalk (from the story) it will be a cable reaching up beyond geo synchronous orbit, on which an elevator will run payloads up and down, NO rockets.
Right now work is being done with carbon nano tubes, to build a cable strong enough so it will be able not just to support its own weight from orbit down to earth's surface, but that can carry the weight of the elevator.
At the very top it will need a counter weight to hold the cable taut, and from which space craft will be launched at the full speed at which the end will orbit the earth. Like a sling shot.

Answer 4

There are THREE things that are required of the "satellite" (man made or natural) in order for this to work: 1) The satellite MUST be geosynchronous (Mars-synchronous??). That is, it MUST be in an orbit such that it remains directly over the same position on the planet at all times. This is so the the planet-end of the shaft can be attached to ONE point on the planet. This point CANNOT move! {if the planet-end of the shaft were left floating, it would wobble and eventually fall apart. BOTH ends of the shaft MUST be solidly affixed to their respect planetary bodies.] 2) The orbit MUST be circular, not "egg" shaped. the shaft of the elevator is like a fixed "radius" which canNOT be changed. ANY variation in orbital height, even as little as a few inches, would pull the elevator shaft apart. 3) The satellite's rotational period must be exactly equal to its orbital period, like the earth's moon. It MUST present the same side of the satellite to the planet atl ALL times, so that the shaft of the elevator can be hooked to ONE spot on the satellite. I don't know of ANY moon for ANY planet that does this. ONLY the Earth's Moon meets (3), above, but does NOT meet (1) or (2). The ONLY solution to the orbiting end of a "space elevator" MUST, at this time, be a man-made satellite or space station. Man-made satellites could have "steering jets" (the current ISS does) to keep it properly aligned and at the correct orbital height.

Answer 5

I saw it on Discovery Channel. They're literally going to build an elevator to space. It's going to be accomplished by sending a spacecraft to the moon with elevator cord so we can travel to the moon and back by elevator. A couple of teams have tackled this project as a competition. To win, they had to build a smaller elevator that was supposed go a certain distance in a certain amount of time.

It's pretty cool.

Answer 6

Heinz's answer is correct. Many think this idea is recent and novel, however, Frederik Pohl used the idea in his sci-fi book MINING THE OORT some years ago where such a similar device was used to get things to and from the surface of Mars. There are still many engineering and technical hurdles to overcome before such a device can be made a reality.

Answer 7

Space elevators are only small rockets, attached to the satellites, ejected in to space by a rocket above earth, to further elevate the position of satellites, these booster rockets were fired to keep the satellite to the desired elevation. These booster rockets are called space elevators.

Answer 8

Like the others say!! My thoughts are what would something that tall be like with the difference in the atmosphere on earth and then going up through out into outer space??

Answer 9

A theoretical alternative means of getting people and cargo into space.

Answer 10

Like the others say, also what a great way to spend billions of bucks, and not succeed.