From: vince@offshore.ai (Vincent Cate) Newsgroups: sci.space.policy Subject: Tethers and Radiation (was Re: beanstalks ... References: <40C0B48F.F477E3F7@mchsi.com> <832ea96d.0406041927.6fe214cb@posting.google.com> <832ea96d.0406051245.1c648e2d@posting.google.com> <40C2419C.97375E5A@hate.spam.net> <40C2F8F2.2C7B3E7E@nospam.com> <9186edb5.0406060628.1f7d3ce@posting.google.com> <40C3B4A9.673AAF6D@nospam.com> NNTP-Posting-Host: 209.88.68.230 Message-ID: <9186edb5.0406070445.43283f5a@posting.google.com> Andrew Nowicki wrote in message news:<40C3B4A9.673AAF6D@nospam.com>... > Vincent Cate wrote: > > Are you saying a rotovator that touches Earth's surface has to extend > > into the Van Allen belts? (not arguing just was not clear) > > No, it does not, but the skyhook by definition extends into > the Van Allen belts. But you have this claim that plastics can not be used in the rotovator section (http://www.islandone.org/LEOBiblio/SPBI122.HTM). So once again the bad name of beanstalks or skyhooks tarnishes the good name of rotating tethers. Please move the comment so it is clear that skyhooks have the problem. 1/2 :-) > Plastic parts of old solar panels are often warped, and > aluminized Mylar balloon named Echo has crumbled. I guess that high > temperature does more damage to plastics than space radiation. > Fortunately, the temperature can be reduced by shading the tether. > I hope that shaded plastic tether in low Earth orbit can survive long > enough to do useful work. Atomic-Oxygen, Ultraviolet radiation, and max temperature can all be very hard on plastic in space. These seem to be the big problems in LEO. All of these can be controlled with a coating on the tether (though how well is not tested yet). Since living things can survive the ionizing radiation of space for reasonable periods of time (more than a year) it really seems that a plastic rotating tether should also survive the radiation with limited degradation (outside the Van Allen Belts). It would be so nice if we had an orbiting laboratory that could do little experiments like putting some Spectra-2000 kite string outside and seeing how much force it took to break off the end each month for a year or more. Could do this with different coatings and see how things worked out. -- 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