Given that there, at one time, was h20 on mars, even though (at
this time),
we don,t know for how long, what is your probability estimate
that at least
some bacteria will be found by one of the current probes on the
surface.
Something like this isn't amenable to "probability estimates."
There is no
way to estimate a probability, because probabilities are based
on
statistical outcomes of previous experiments (of which there are
none).
So the answer is: I don't know. I'm certainly hopeful, and
my suspicion is
that water + carbon + energy = life. However, even if life had
exsited on
Mars, or even if it exists now, it's unlikely to be found by one
of the
current probes for the same reason that you're unlikely to find
a fossil in
your back yard: fossilization is a fickle process and large areas
must be
searched to find one. It's unlikely that anything other than a
manned
mission will discover fossils on any planet.
Answers provided by HSU Astronomy Professor David Kornreich.