Date: Sun, 22 Dec 2002 19:23:17 -0800 Subject: Re: Technical obstacles to cheap LEO access From: vince@offshore.ai (Vincent Cate) Newsgroups: sci.space.tech References: <3eb6e2ae.934151178@nntp.ix.netcom.com> <497d06a6.0212012307.3b9d17e@posting.google.com> NNTP-Posting-Host: 207.42.133.230 Message-ID: <9186edb5.0212221923.7711d058@posting.google.com> whmook@hotmail.com (William mook) wrote in message news:<497d06a6.0212012307.3b9d17e@posting.google.com>... > For example, cables >in orbit that spin in a way to reduce the speed of the tips to near >zero, as they come into contact with the Earth's upper atmosphere. >These can be built with existing materials. Unfortunately, even small >systems weight 10,000 tons or more, and they must be reenergized by a >process yet to be developed. A buildable spinning tether can make it so your rocket only needs to get to half orbital speed. Then it is as if you only need the second stage of a 2 stage rocket. This could easily cut the cost by a factor of 10. This type of tether system may be 100 times the mass of the payload, but this is very reasonable for a small payload. Also, a re-usable rocket that goes to half orbital speed is far easier to make. If you have re-usable rocket that gets to a tether, your costs get amazingly low. To reenergize a tether you can use an electrodynamic tether that pushes on the Earth's magnetic field. The process needs development, but it is not magic. See http://spacetethers.com/ for more on this approach. -- Vince