Originally Posted by **********

Mars is more interesting. The crevices which look like dried river beds could have been carved by ice or liquid water. If it had water, it might have had life.

Since the moon never had an atmosphere and is too small to have had one, it never had liquid water and therefore no life at all.

Mars on the other hand is a good sized planet that is within the "goldilocks" zone (i.e.: Not too close and not too far away from the sun). The chances of Mars having life on it in the past is high, which makes it worth exploring.

Next stop : Europa!