for National Geographic News
NASA's THOR mission may blast an enormous crater on Mars to search for water ice in latitudes that could support life on the red planet.
Intriguing gully- and glacier-like features, spotted by telescopes and orbiting spacecraft, suggest there may be a large body of frozen water beneath the planet's dusty surface.
The proposed mission aims to break new ground in search of the truth.
"The time has come to take Martian studies a step furtherand deeper," said principal investigator Phil Christensen of Arizona State University's Mars Space Flight Facility.
"At the moment, the deepest we've dug on Mars is probably a foot [30 centimeters]," he continued.
"A lot of people, myself included, believe that the upper surface may be dry and desiccated, bombarded with ultraviolet rays, and that the interesting stuff may not start until you're down a meter or two [three to seven feet]."
The THOR plan is part of NASA's Mars Scout program, which funds outside projects that complement the space agency's ongoing Mars Exploration Program based at JPL.
The relatively low-cost missionbudgeted at 450 million U.S. dollarsis designed to capture a first glimpse of subterranean Mars and possibly pave the way for more detailed study.
THOR (Tracing Habitability, Organics, and Resources) is one of several candidate projects up for the latest round of Mars Scout grants. NASA will narrow its list to three contenders by November of this year and will make a final decision on a winner by January 2008.
If green-lighted, THOR would crash a copper "impactor" projectile into Mars at high speed. No one knows exactly how big of an impact the collision would make, but scientists expect to form a crater more than 30 feet (10 meters) deep.
An observer spacecraft would release the projectile while in orbit around Mars.
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