QUESTION:
My science teacher has just assigned a project and my group and I 
have chosen a "Mission to Mars".  The purpose of our project is to 
prove wheather bacterial organisms exist on Mars. If you could please 
send back information on how bacteria moves and what instruments in 
space could help find them.

ANSWER from Mike Mellon on November 16, 1999:
You could look for bacteria by how it breaths when it eats food. Put a
martian sample that you suspect may contain some bacteria into a
closed chamber. Add some food, water and oxygen. Then look for a decrease
in the oxygen and an increase in other byproducts such as carbon dioxide,
or the production of hydrocarbons like methane. If you see these changes
in the gases in the chamber containing one of the martian samples, you
can then confirm your result by looking for the bacteria in a microscope.
You could also heat the sample to sterilize it and test it again to make
sure the changes in the gases are not due to non-biological chemical
processes.

Experiments similar to this were conducted by the Viking Lander spacecraft
which were sent to Mars in the 1970's.