X-Message-Number: 22735 From: "Brett Bellmore" <> References: <> Subject: Re: CryoNet #22731 Space Date: Sun, 26 Oct 2003 07:47:23 -0500 "... There is no unobtainium magic material in that scheme, the tower is made of aramide, the rocket may be a simple first stage of a present day booster, the tether is a kevlar-aramide element, the NTR could be a scaled down version of the 40 years old Nerva... The problem is political not technical. ... >van Bozzonetti." Carbon nanotubes, which are more than sufficient for a ground to geosynchronous orbit tether, are hardly "unobtainium" these days. The material exists now, it's just a question of improved manufacturing. And a tether in tension is at least naturally stable, which is more than can be said for a tower in compression. http://www.isr.us/SEHome.asp The basic problem with your proposal, though it might be workable technically, is that it requires the development of four separate systems, resulting in a huge multiplication of potential failure modes. In particular, I'm dubious about launching a chemical booster from the top of an inflated tower. Balloons and huge rockets with a significant tendency to explode do not mix well. Brett Bellmore Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=22735