> Suppose we've already got a couple of dozen asteroids captured, orbiting
> Earth somewhere outside geosynch. If the motors that put them there
> haven't been dismantled, could one of these rocks be shifted into the
> path of a killer comet, to deflect it and/or break it up?
Sounds like a fun idea. The trick would be to get them into a
collision course; changing orbit would be rather slow, so you still
need plenty of warning to change the inclination and phase to get a
hit. The precision required is very high, on the order of hundreds of
meters, but in principle it could be done (caveat: comets are a bit
wobbly due to their irregular gas eruptions).
If a "tame" almost stationary (in the Earth frame) asteroid split a
killer comet, we would likely still get plenty of debris swishing
around our ears (and satelites!). A better solution would be
deflection, which requires it to move fairly quickly. Sounds like we
want very powerful engines on those tame asteroids.
(This system also has an unfortunate weapons potential: just
neutralize the momentum of the asteroid, and it will drop on the
continent of your choice. Ouch!)
-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y