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.
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