Asri-unix.641
net.space
utcsrgv!utzoo!decvax!duke!chico!harpo!mhtsa!ihnss!ucbvax!menlo70!sri-unix!CARLF@MIT-AI
Mon Jan 25 12:42:23 1982
Collisions with skinny skyhook
CARLF@MIT-AI 01/25/82 12:59:41 Re: Collisions with skinny skyhook
To: Space-Enthusiasts at MIT-MC
	Mr. Moravec is quite correct about the width of the skyhook.
I erroneously assumed that anything that strong had to be big. However,
I believe that he has erred in his calculation of the damage rate for the
skinny skyhook. It is true that the skinny version has 1/50 of the area
of the fat version, but this does not reduce the damage rate by a factor of
50, since it is now possible to break the cable with very much smaller
projectiles. Instead of a 17cm diameter projectie, we now need only a 0.34cm
projectile, which would wiegh about 0.2 g. The flux of such particles is
about 0.1 impacts / m^2 / yr. A 500 km section of 5 cm wide cable has
an area of 25,000 m^2, and thus will be hit 2,500 times per year, or about
once every four hours.
	The problem is that the danger rises exponentially with the skinniness
of the cable. It is hard to see how to solve this.

			-- Carl

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