National Geographic Today
Next month three missions to Mars are scheduled to lift offtwo American and one Europeanin a rush to take advantage of a trajectory between Earth and the Red Planet that only happens every 26 months.
NASA's Mars Exploration Rovers (MER) A and B are twins, to be launched on June 5 and June 25, respectively, bound to land in January 2004 in different areas of Marsthe Gusev Crater and the Meridiani Planum.
The European Space Agency's Beagle II is due to land in Isidis Planitia, where it will stay put for its six-month mission. The compact Beagle II will look for traces of life.
Scientists have tested the rovers and other Mars instruments in what they call the sandboxa large room at the Jet Propulsion Laboratory (JPL) in Pasadena, California, with volcanic rocks, dirt, and sand that simulate the Martian landscape.
The rovers are robo-geologists. Their goal is to search for water past and present.
"There is strong evidence from orbital missions that liquid water was once [on the Gusev Crater and Meridiani Planum]," says Steven Squyres, a planetary scientist at Cornell University in Ithaca, New York, and a team leader for the scientific instruments in the MER program.
"Mars today is cold, dry, and barren, not particularly friendly to life," says Squyres, "but data from orbiters [like Mars Global Surveyor and Mars Odyssey] suggest a very different history."
Hints of Water
Dramatic images of what appear to be river channels, lake beds, and mineral deposits suggest that Mars may once have been warmer, wetter, and more livable.
The Meridiani Planum contains gray hematite, a mineral that is a "powerful clue" to water's former presence, Squyres says.
In Michigan's upper peninsula, for example, gray hematite formed in deep water bodies millions of years ago. Deposits also appear in hot springs and in fine veins in underground rock where cold water trickles through.
The Gusev Crater is completely different from the Meridiani Planum, says Squyres. "It is a big hole in the ground with a water-carved channel, or dry river bed, running into it. If you know how to make these formations without water, tell me about it."
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