From: vince@offshore.ai (Vincent Cate) Newsgroups: sci.space.policy Subject: Re: Cheapest fastest extraterrestrial resources References: <1085645273.270442@kyle.snap.net.nz> <1085663181.86393@kyle.snap.net.nz> <40B6235A.A1C2FA57@earthlink.net> <40B630EE.4030304@tabletoptelephone.com> NNTP-Posting-Host: 207.42.133.252 Message-ID: <9186edb5.0405272120.3d6b0748@posting.google.com> Doug... wrote in message news:... > It seems to me that picking up *any* mass at one end of the rotating > tether is going to change the center of mass of the tether, and thence > the center of rotation. Yes. But if you have a 2,000 Kg probe picking up 5 Kg from the moon at a time it does not change by much. > And since the center of rotation is the > "point" that will define the tether's orbit, grabbing or dumping mass > from either end ought to cause such tremendous force on the tether that > it will either oscillate itself to death or become a hopeless set of > twists and loops. No. There is a wave but you can remove this by using the winch to pull more/less at the right times. The normal way is to pickup something at your perigee. This lowers your apogee. To fix things back you can pickup extra mass, winch in partway so you spin faster, and toss some of the extra mass backwards the next time you pass through your perigee. > Do the computer simulations take into account the tensile strength, > flexibility, etc., of available materials, I wonder? Of course the simulations take this into account. My simulator is free and a simple to run Java applet. The source code is also online. Check it out at: http://spacetethers.com/spacetethers.html -- Vince