QUESTION:
Since it looks like a microbial life could exist on almost every planet or
moon, is it possible that such life still exists on Mars?

ANSWER from Jack Farmer on October 4, 1997:
The prospect of extraterrestrial life is in fact limited to only a few
places in the Solar System, and not "almost every planet or moon" as you
suggest. The search for extant life is thought to be equivalent to the
search for liquid water, and that appears to be limited to only a few other
places in the Solar System. In that context, the two most exciting prospects
to date include 1) the subsurface of Mars and 2) the subsurface of Europa.
In both of these examples we would need to access the deep interior of the
planet or moon via deep (kms depth) drilling. At those depths, pressures and
temperatures would be high enough that we have the chance of encountering
liquid water, and therefore life.

Jack Farmer