QUESTION:
Are there any materials on Mars that could be used to build
a vehicle or use for fuel?

ANSWER from Cathy Davis on December 27, 1996:
Most scientists and engineers consider using the carbon dioxide (C02) 
of the atmosphere as a source for rocket fuel. Using an energy source 
such as a solar cell array, CO2 can be broken down into carbon 
monoxide (CO) and oxygen (O2).  The CO can be burned with O2 as 
rocket fuel.

ANSWER from Phil Christenson on March 24, 1997:
Yes, there are lots of materials on Mars that would be
useful.  Mars very likely has the same
types of minerals we have on Earth, which could be used
for building materials such as concrete.  It also has
rocks and minerals with iron and aluminum in them which
could be used to build buildings, vehicles, and other
things.  Most importantly, Mars has ice made of water
which could be used for drinking water and for growing
food.