QUESTION: 
If there is life on Mars, would a meteor hitting Mars kill the life?

ANSWER from Jack Farmer on November 11, 1996:
The Earth and Mars are both vulnerable to the effects of large impacts,
and we really don't know what all those effects might be. But NASA has
scientists at the Ames Research Center who worry about such issues,
and they have models that suggest impacts of objects several hundred
kilometers in diameter might well extinguish much of the higher life forms
on the surface of the planet and down to a certain depth in the oceans. It
may actually be quite hard to extinguish subsurface microbial life by
impact, and in that respect, both the Earth and Mars would be likely to
hang onto at least the microbial part of their biospheres (assuming Mars
has one of course!) during giant impacts.