From: vince@offshore.ai (Vincent Cate) Newsgroups: sci.space.tech Subject: Re: Beanstalk for a Billion Bucks References: <3E5F78D7.887D89ED@netscape.net> NNTP-Posting-Host: 209.88.68.230 Tom Carman wrote in message news:<3E5F78D7.887D89ED@netscape.net>... > I notice that all of the discussions are focussed exclusively on the > beanstalk concept. Do you have any opinion on something like the > "hypersonic skyhook"? Granted that it doesn't have nearly the utility > of a beanstalk; on the other hand, it is do-able with the materials > already in hand. I think the beanstalk concept is easy for anyone, including reporters, to understand. So it gets more press. Both the beanstalk and the non-rotating tether talked about in "hypersonic skyhook" have the problem that you need to climb the tether, and you need power to do that. Wires are really heavy, so you probably only have solar power. We can make cars that do 100 km/hour on flat ground, but climbing a rope with a solar powered elevator is probably much slower. The distances are so large that you are probably talking like 10 to 30 days for climbing the beanstalk. The payload might only be 1/100th the mass of the beanstalk tether. So not only does a beanstalk need a rope 10 times stronger than any rope you can buy today, it would take it years to lift its own weight. The "hypersonic skyhook" is not so bad, but still probably days to climb as it is covering the high gravity part of the beanstalk. A spinning tether seems more promising because it can built with real materials you can buy today, and it can accelerate and toss something in like 10 minutes. It does not matter too much how heavy your solar cells and ion-drives are that keep your tether up to speed, because they are not with the payload. See my site at http://spacetethers.com/ for more info and a simulator. -- Vince ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Vincent Cate Space Tether Enthusiast vince@offshore.ai http://spacetethers.com/ Anguilla, East Caribbean http://offshore.ai/vince ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You have to take life as it happens, but you should try to make it happen the way you want to take it. - German Proverb