Set for a 1:28 p.m. liftoff Monday, Maven will study the Red
Planet's upper atmosphere and history of climate change.   Water
is believed to have flowed through rivers and lakes on ancient
Mars, supported by a thicker, warmer atmosphere.  Microbial life
might have flourished in that climate more than 3.5 billion
years ago.  STORY: NASA's Mars orbiter remains on track for Nov.
18 launch STORY: Mars mission preparations continue despite
shutdown  But today the Red Planet is a cold, dry desert.  "Why
do we appear to have had a climate on Mars that could have
supported life at the surface early on, and we don't today?"
asked Bruce Jakosky of the University of Colorado's Laboratory
for Atmospheric and Space Physics, the lead scientist for NASA's
Maven mission. "Something fundamentally changed, and we want to
understand what those changes were."  The $671 million Maven
mission hopes to begin solving that puzzle with a 1:28 p.m. EST
blastoff Monday atop an Atlas V rocket from Launch Complex 41 at
Cape Canaveral Air