Posers and Puzzles
23 Jul 06
26 Jul 06
Originally posted by FabianFnasNo, the space elevator is in a 24 hour orbit but it has to be done by centrifugal and centripital forces not a real orbit. The elevator people are proposing a rope 62,000 miles high, about 100,000 Km I think.
Then you have to look harder. We've been discussed the geosync orbits for a while. That's the answer.
Do I have to write it out? Isn't it enough to hint the anser? So you know that I know?
I don't like to spoil the fun for the others...
So Presumably at an altitude of 22,241 miles you will be in that orbit if you stepped off. However you have to add a couple more Km/sec.
velocity if you want to escape the earths gravity. However, since the rope is many thousands of Km longer than that, at some place going outward on the rope, you will find you can step off the rope and not come back down to earth unless you either have a rocket to do that or can come back down the rope. You will be at an altitude where the orbit of the rope produces a velocity greater than escape velocity. The question is, how high up the rope do you have to go to find that you are at escape velocity just by being on that rope. Like I said, its a lot less than 100,000 Km but more than 36,000 Km which is about the distance of a geosync orbit if you were actually orbiting which in this case you are most decidedly not.
26 Jul 06
Originally posted by sonhouseThen I think you have to rethink.
No, the space elevator is in a 24 hour orbit but it has to be done by centrifugal and centripital forces not a real orbit. ... [text shortened] ... Like I said, its a lot less than 100,000 Km but more than 36,000 Km which is about the distance of a geosync orbit if you were actually orbiting which in this case you are most decidedly not.
Geosync orbit it is. About 36 000 km.
But if you mean the distance you need to once in for all leave the gravitational filed of the eartch alltogether. Then I agree that the length of the rope has to be quite longer. But just to step off the rope and find yourself in a circular orbit - then your're at the geosync orbit, as said earlier.
27 Jul 06
Originally posted by FabianFnasThats what I am getting at here. The cable design calls for it to be about 100,000 Km long with a big weight at the end, a space station if you will. It has to be accelerated to a speed of about 12 Km/sec so the cable will be taut. If they do that correctly the cable will jutt straight away from the earth into space and stay that way. I imagine a continued need for rockets on the upper end to adjust the velocity every now and again to keep it vertical but in that situation, you can crawl up the cable and at 36,000 Km step off and you will be in a 24 hour orbit. However the cable is some 60,000 Km longer than that so you can keep on riding up the cable. At some point the velocity of the cable itself will be faster than escape velocity of the earth and you can step off and never come back down and if you keep going up you can step off and if you do it right, aim yourself at the moon or a distant planet and you will be off and running without further need for rocket fuel, of course you need more to stop at the other end but you have just gotten out of earths gravity for practically free. So how high up the cable do you have to climb to be able to step off and not fall back to earth?
Then I think you have to rethink.
Geosync orbit it is. About 36 000 km.
But if you mean the distance you need to once in for all leave the gravitational filed of the eartch alltogether. Then I agree that the length of the rope has to be quite longer. But just to step off the rope and find yourself in a circular orbit - then your're at the geosync orbit, as said earlier.
27 Jul 06
Sonhouse writes in his first posting of this thread::
"... like at what altitude can you step off and be in orbit ..."
Here we have geosync orbit. When you've climbed up the beanstalk, then at an altitude of 36 000 km you find yourself hanging with no velocity relative to the bean stalk itself.
And then he continues:
"and what altitude can you step off the cable and be at or above escape velocity?"
And this question I havn't answered. Very interesting question problem!
I'm sorry that I overlooked the second part. My fault.
27 Jul 06
Originally posted by FabianFnasI don't see this second idea talked about. I think it would make the idea of the orbital route secondary in importance, the idea that you can just send stuff up to a certain altitude and at a certain time let go and you would continue on your way but faster than escape so you just keep going and the fact that the elevator would be on the equator would mean you would be automatically in the plane of the ecliptic which means you can theoretically aim at most any destination in the solar system with not much more energy needed, since you have already climbed out of the gravity well of earth. The earth spins pretty close to the plane of the rest of the planets in the solar system so not a lot of manouvering needs to be done. Very interesting way to get to other planets in our system. I am sure we can calculate the exact time around the orbit to let go and be correctly aimed to most any spot in the solar system. Of course it would just be the opening round of acceleration, probably more would be needed but you would be able to have a much larger payload because you are already starting off a something greater than escape velocity.
Sonhouse writes in his first posting of this thread::
"... like at what altitude can you step off and be in orbit ..."
Here we have geosync orbit. When you've climbed up the beanstalk, then at an altitude of 36 000 km you find yourself hanging with no velocity relative to the bean stalk itself.
And then he continues:
"and what altitude can you step ...[text shortened]... y interesting question problem!
I'm sorry that I overlooked the second part. My fault.
13 Aug 06
1 edit
Originally posted by ThudanBlunderNo, not yet, Thanks for the link, I haven't been there for a couple of years and thats the link I had asked for earlier, remember?
Have you posted it at http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi#riddles_cat?
You aren't trying to say you think its too tough a problem for YOU? I can't believe that.
The only thing you need to realize is we are already about 6400 Km from the center of the mass of the earth, everything else just falls over after that.