Asri-unix.1347 net.space utzoo!decvax!cca!KING@KESTREL@sri-unix Tue Apr 27 14:46:33 1982 projectile pollution in space From time to time someone proposes electric reaction engines for deep space manouvering, based on the ejection of large numbers of small projectiles. Such a proposal recently appeared in this forum. I made back-of-the-envelope calculations on the effects of using a billion such projectiles (100 per second for several months; hardly an implausible launch schedule). This might be used, say, to move 1/e of an e-million-ton asteroid (100 meters diameter) into Earth orbit (delta-v of 10 KM/sec) using a billion 1-KG. projectiles. Making reasonable assumptions about the volume of space in the Solar System that these projectiles will spread out into, we get an exposure of 1/10e6 KM^2-yr. from this one asteroid movement. This seems like a meager increase, but it seems unlikely that this system will only be used once, to move a single relatively modest asteroid. It also seems unlikely that our space exposure will be forever limited to 1 KM^2. I rather assume that in the future our exposure will be "on the order of" thousands of square KM, and that we will move thousands of asteroids (or bigger ones). To make a long story short, do proposals for deep space propulsion by reaction motors ejecting projectiles properly consider the pollution problem? How does the artificial meteoroid concentration compare with that of the natural population? With that of the natural population in meteor showers? How nonuniform would these non-uniform meteoroid swarms be after (say) a year? I'll do more calculations unless someone can point me to a reference in which this point has already been considered. ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.