Post
by ajhil » Thu Nov 10, 2005 5:52 pm
An interesting concept, which probably shouldn't be dismissed out of hand.
(1) Collisions may be more efficient at transferring momentum, but this method is feasible only for rocky asteroids, which won't shatter. A comet or water-ice asteroid might fragment on impact, making the problem potentially worse.
(2) As some postings point out, 20 tons is a modest size for towing an asteroid. The small gravitational attraction would certainly limit the acceleration that could be achieved.
(3) Rather than rely on any kind of tether, physical or otherwise, why not land on the asteroid and install a reactor and ion drive on its surface? Unless the asteroid was a conglomerate of separate bodies, this would allow much greater thrust to be applied.
(4) Another method (which would preserve the visual impact of this painting) involves a "tug" with diametrically opposed ion thrusters. By hovering close to the asteroid and directing one thruster at its surface, while the other thruster maintained the tug's position, substantial momentum could be transferred to the asteroid. In addition, this might also transfer a large electrical charge, raising the interesting possibility of an "electrostatic" tether, which could be orders of magnitude stronger.
(5) I understand the purpose of showing the half-illuminated Earth in the background, but, since its apparent size approximates that of the moon from Earth, it must be on the order of only a million miles away. One would hope that the tug's work has already been accomplished at this point!
(6) As for the asteroid towing the rocket vs the other way around, neither viewpoint is technically accurate. In fact, the rocket's ion thrusters will accelerate the combined mass of the rocket-asteroid system. Neither one "tows" the other [/i]per se.
A.J. Hill
"The sun is but a morning star." - HDT