Discussion
The infamous 'space escalator'. Very good idea. How they will stop it tumbling to earth I don't know. The satellite will have to be heavy enough to equalise the pull of gravity, and the outward push of the orbit...
I recall Clarke used a bit meteorite that was used to balance it all nicely. How easy it is to do is another matter.
I recall Clarke used a bit meteorite that was used to balance it all nicely. How easy it is to do is another matter.
Some one said something a bout tubular carbon summit or others. It was in the other thread. I can't see them having anything to do it at the moment though. At least nothing reliable enough to make a 200 mile high tower, that could come down with an almighty thud should something fail.
big martin said:
A lift into space?. A platform in the Pacific ocean attached by cable to a satellite. Start date to be built this year backed by NASA any come back.
Who says construction is to begin this year?
IIRC the substance needed to build it is carbon nanotubes, and so far they can only make those in very small minute quantities.
We've only recently discussed the "space elevator" idea and, if I might say, in great detail too.
See
www.pistonheads.com/gassing/topic.asp?t=196825
>> Edited by JonRB on Wednesday 17th August 00:19
See
www.pistonheads.com/gassing/topic.asp?t=196825
>> Edited by JonRB on Wednesday 17th August 00:19
How does this work? A rocket uses masses of power to escape earths gravity, once in orbit it stays put, more or less, albeit a decaying orbit. But anything that is tethered to the earth and up into space doesnt have any energy or velocity to escape gravity, surely it cant stay up and will come down under its own weight, space is what? 50 miles up, but the cable will have weight, metre by metre, multiplied up to the point where the top wont weigh anything because it is in space, but surely the bit that isnt will want to fall, pulling the top bit down with it.
It stays up the same way satellites do. The centre of mass of the thing is slightly beyond the geostationary orbit. So as it's fixed at one end and going round with the Earth it generates enough centrifugal force to keep itself up and provide a bit extra to take the weight of things climbing the string.
The counterbalance mass on the other end can be a meteorite or something or it can be just the mass of the cable extended until it's heavy enough, or a combination of the two. Extending the cable gives the advantage that it's easy to accelerate spaceships up to speed to fly off somewhere else without having to burn much in the way of fuel.
Having the thing fall back to earth due to damage isn't a big problem because the string is so light it just falls like a feather. Things climbing it will need some gliding ability in case of emergency, though if they're high enough they'll just burn up.
The best material known for the string at the moment is carbon nanotubes but there are problems both with making high quality ones in sufficient quantities and with making a cable out of them. There is no particular reason to suppose these problems cannot be solved.
The counterbalance mass on the other end can be a meteorite or something or it can be just the mass of the cable extended until it's heavy enough, or a combination of the two. Extending the cable gives the advantage that it's easy to accelerate spaceships up to speed to fly off somewhere else without having to burn much in the way of fuel.
Having the thing fall back to earth due to damage isn't a big problem because the string is so light it just falls like a feather. Things climbing it will need some gliding ability in case of emergency, though if they're high enough they'll just burn up.
The best material known for the string at the moment is carbon nanotubes but there are problems both with making high quality ones in sufficient quantities and with making a cable out of them. There is no particular reason to suppose these problems cannot be solved.
big martin said:Why do you need carbon nanotubes? Surly it would be easier to build a bloody great tower out of composite materials and just used one of these wonder materials in the cable instead? I think it could be done if it was a collaboration of technologies and we had a bugger load of funding.
alexkp I do agree with you the nanotube cables are far from tested maybe the start of the project is on the drawing board, what do you think??
Wind shear would be a huge problem though.
How do you get the cable from space to earth or visa versa?
speedy_thrills said:
alexkp I do agree with you the nanotube cables are far from tested maybe the start of the project is on the drawing board, what do you think??
Why do you need carbon nanotubes? Surly it would be easier to build a bloody great tower out of composite materials and just used one of these wonder materials in the cable instead? I think it could be done if it was a collaboration of technologies and we had a bugger load of funding.
Wind shear would be a huge problem though.
How do you get the cable from space to earth or visa versa?
The cable needs to be a minimum of about 36,000 km long - that's why you need a stupidly strong material, and carbon nanotubes look like the best candidate at the moment.
A manufacturing plant opened earlier this year just the the purpose of producing nono-tubes for an elevator. I'll see if I can find a link...
http://science.slashdot.org/article.pl?sid=05/05/01/0415248&tid=160&tid=126&tid=14
Edited for link. Seems it's not just for the lift.
>> Edited by uriel on Wednesday 17th August 08:18
>> Edited by uriel on Wednesday 17th August 08:20
http://science.slashdot.org/article.pl?sid=05/05/01/0415248&tid=160&tid=126&tid=14
Edited for link. Seems it's not just for the lift.
>> Edited by uriel on Wednesday 17th August 08:18
>> Edited by uriel on Wednesday 17th August 08:20
Hmm carbon cable, gonna be a bit of lightning coming down around that then? Gassing Station | The Pie & Piston Archive | Top of Page | What's New | My Stuff