QUESTION:
Why do you want to find life on Mars and what will you do if you find 
life on Mars? What might this indicate?

ANSWER from Cheick Diarra on November 18, 1996:
If we find life on Mars, this would help answer a question we have always
asked: "are we alone in the universe?"  We would know that life is not unique
to Earth.  We might find out if life on Earth came from Mars, or vice versa.
Also we could start to understand the conditions under which life
can exist.  Later, with the help of technology, we might be able to 
catalogue the planets in other solar systems that present those conditions. 

ANSWER from Jack Farmer on February 3, 1997:
We visited Mars several times in the 1970's with robotic missions 
called Mariner 9 (an orbiter) and Viking(2 orbiters and 2 landers).
We would like to go back  to better understand how the Earth and Solar
System originated, and to see if life ever developed elsewhere,
beyond Earth.  Mars is really the best place to go to study such
things for basically two reasons: 

1) the surface of Mars is very old and preserves a record of the
earliest events that shaped the inner solar system (this early rock
record has been lost on Earth because of plate tectonics and weathering
and erosion). 

2) Mars was more Earth-like early in its history and is the other
planet in our solar system most likely to have supported extensive
liquid water environments where life could have developed and survived.
 During the early history of Mars, at the time life first developed on
Earth, the planet had water at the surface where it formed extensive
valley networks and may have even pooled to form large lakes.  If life
developed here on Earth, we have to ask "Why not on Mars?". 

Finding life elsewhere would help us better understand life on Earth
and how unique our biosphere is in the Universe.  And by understanding
the way life developed on another planet, or why it did not develop, we
can better determine how to manage environmental changes taking place
on our own planet.  For example, very early in the history  of Mars
(around 3 billion years ago) the planet appears to have lost its
atmosphere, eventually refrigerating to form an icy cold desert where
all the water, so crucial for life, is frozen.  The surface of Mars
today is far to harsh for life as we know it to exist. This is mainly
because liquid water is unstable there and can only exist as vapor in
the atmosphere or as ice (Mars has ice caps at both poles). Our other
nearest neighbor, Venus, may have also had a period early in its
history when liquid water was present on the planet along with the
opportunity for life.  But something also went wrong on that planet
sending it into a "runaway Greenhouse effect" that has allowed the
surface to heat far above the  stable point for liquid water and life. 
So far, the Earth has managed to stay within the habitable zone where
liquid water is stable.  If we can better understand the processes that
have destroyed habitability on Mars and Venus, we can better plan our
own future, and perhaps mitigate some of the problems of pollution and
resulting climate change that are causing problems for our biosphere.