On Mar 9, 8:37*pm, Orval Fairbairn wrote:
In article ,
*"John F. Eldredge" wrote:

On Tue, 05 Mar 2013 08:31:02 -0800, Robert Clark wrote:

Speculation here that such an impact could make Mars habitable:

Rush to Mars: Comet impact could make Red Planet inhabitable. Published
time: February 28, 2013 16:32
http://rt.com/news/mars-comet-tito-flyby-601/

* Bob Clark

You would need thousands of comets' worth of gas to make Mars' atmosphere
dense enough for human life, plus you would probably have to introduce
some sort of genetically-engineered plant to release free oxygen, then
wait a long time.

That's a pretty good assessment.

if theres enough water under the mars surface it could be electrically
turned into oxygen and hydrogen to provide breathable air. or
genetically engineer some lichen that would produce air.