Space Elevator Homework Help!?

Question

I got some questoins assigned on Space Elevators, and im finding some diffuculty finding the awnsers. Can someone please help me out?
How much would it cost to build a space elevator?
How would they prevent the space elevator from hitting airplanes?
How thick will the cable that holds the space elevator be?
How long will the cable that holds the space elevator be?
THe person with the most efficent awnsers, will get the best awnser. Thank you very much!

I wouldnt give up on Space elevators just yet, it may take them 40-50 years to build, but new techonlogy such as carbon tubes are coming in that are lighter then steel and more powerful.

Answer 1

One of the design issues associated with building the space elevator is that the cable material would have to be very strong and very light. (I think someone mentioned steel is not going to do the trick. This is correct.)

However, believe it or not, emerging technologies such as carbon nanotubes are quickly bringing what might seem a silly notion a very real possibility.

Check this out:
http://science.nasa.gov/headlines/y2000/ast07sep_1.htm

Just type in "space elevator" into any search engine, and you will soon find out there is PLENTY of information to answer the questions you have above.

Good Luck!
-jtd

Answer 2

The Space Elevator is waiting on the development of a material that is strong enough to support not ony its own weight but also the payload.
The theory is that a space station in GEOSYNCHRONOUS orbit could be tethered permanently to a point on the Earths surface. There would have to be a 'cable' with a mass attached heading away from the Earth to balance the mass of the 'down cable'. As the payload climbs the cable to the station the mass on the other cable has to be reeled in to counterbalance the rising payload.
Since the station must be in geosynchronous orbit and the height of that orbit has to be 23,000 miles, then the two cables have to total 46,000 miles in length.
Arthur C. Clarke was the man who invented the idea and he wrote a novel based on his idea. I suggest you read his "Fountains of Paradise" which explains the theory in laymans terms and is a worthwhile read in any case.

Answer 3

Wow...That is a whole bunch of questions in one question. you seek the whole stack of information in one little window here on yahoo...Tough assignment.

Okay. First. The Space Elevator would not hit Aircraft. Aircraft "would / could" hit the Space Elevator. One has to believe that certain "do not fly" zones would have to be placed into effect if some structure like this was ever developed.

Second. What is the longest single length of anything solid, twisted, or woven you have ever seen? Certainly it was less than 3 miles long, and most likely (darn sure) was laying horizontally when you saw it. That is, it was not hanging straight up and down.

Third. Nothing has ever been developed yet which will carry its own weight at extended vertical lengths such as ten, fifteen, twenty miles, or more (like fifty miles) which would be required to reach outer space. Now, given that basic materials problem, you wish to add the weight of various elevator loads running up and down the cable/wire/fiber???
Hmm-m-m. Not going to happen.

Fourth. No bearing has ever been developed that will sustain such a load in the harsh environment of outer space...i.e. extreme heating due to massive loads twisting and pulling on the bearing, and extreme cold of the surrounding atmosphere. The problem lies in temperature differential between outside skin and inner friction point differing by thousands of degrees. That bearing point is the failure point for any system you wish to consider. Make it hot and it wants to melt or disintegrate. Make it cool and it is happy until it becomes brittle and wants to fracture, or crack open.

Sixth. Go back to item three. Any cord, wire, or cable which would become the doodad extending from the surface of the Earth up into outer space would have to be strong enough to support 50 miles worth of its own weight. Now if you make it strong enough to carry some kind of load besides its own weight, it will have to be thicker. Well, if it is thicker, it will weigh more and exceed the breaking strength of the material at 50 Mile lengths.

Seventh. Have you ever heard of Tornados, Hurricanes, and Monsoons? These are violent weather disturbances which produce intense winds, updrafts, and downdrafts. The suspended cable would need to be extremely strong to withstand the swaying and whipping action caused by those weather systems. So, the cable would need to be made even thicker and stronger than first imagined. Oh my gosh... If it has to be thicker and stronger it will weigh more and cause the cable itself to break. So the cable now has to be much thicker and stronger...Oops if it is thicker, it weighs more, and will fracture or break because of its own weight. If the cable does not break, the connection point at the bearing will fail because of excessive strain on the joint.

Eighth. Satellites stay in orbit because of the fine balance of their speed versus the pull of gravity. When you add extra pull from the weight of the line going down to the Earth, you increase the downward force pulling the satellite down to the Earth's surface. So, the satellite will begin to fall toward the Earth unless more propulsion is added to the satellite.

This means that a normally happy and inert (no rocket firing) satellite must now have a rocket firing all the time to offset the drag of the cable to Earth...That isn't going to happen either.

The fuel required for such a continual rocket burn would be immense, and worse, the mass of the satellite would change as the fuel was consumed which would alter the orbital path of the satellite (balance between gravity and the mass of the orbiting satellite). Oh, but you can refill the fuel supply...So, you would accept a seesaw orbital path around the Earth for the satellite??? I don't think so...There is a fixed cable length hanging down to the Earth's surface. What is it going to do, pile up all the slack cable in Siberia or the next city?

Enough Said...

Answer 4

It is not possible to hang a steel cable from space to earth. It would be so heavy that it would have to be very large in diameter. It's large diameter would then make it heavier and so on. So without special materials that have not been invented it is not possible.

The tallest towers ever built are less than 2000 feet. A space elevator would be 70,000 ft. Sorry not going to happen.

Answer 5

I know space starts around 62 miles up and the space station is close to 300 miles up.....