To reach Australia's Kalgoorlie lakes, you fly west from Sydney, across the outback to Perth. From there, you can drive inland for 12 hours, or catch a plane. But after landing in the dusty gold-mining town, you'll have to rent a Jeep before the shops close at 5 p.m., and then strike off into the desert on your own.
Kathleen C. Benison and her geology team made the long trip from Central Michigan University in 2001 to study the cluster of highly acidic salt lakes, which she says bear a striking resemblance to waters that once flowed on Mars.
Data from NASA's Mars rover Opportunity have convinced scientists that the planet's Meridiani Planum once flowed with salty, acidic water sufficient to sustain life.
While there's no evidence yet that Martian life did evolve to swim at Meridiani Planum, Benison said there's life in Kalgoorlie's equally inhospitable waters: So why not Mars?
"In recent decades we have found all these microbes on Earth that we didn't know could exist," she said. "Maybe there are different types of life on Mars than we understand. The key is being open-minded, trying to think of all the possibilities and ... how to test for them."
Mars rovers
Since its landing on Jan. 25, Opportunity has been looking for evidence that Mars once had enough liquid water to sustain life.
Last month, scientists announced they had identified a rocky outcrop bearing the mineral jarosite. It's rare on Earth because it forms under unusual circumstances - in lakes, hot springs or ground water that contain sulfuric acid.
Close-up pictures of Mars rocks revealed curious pockmarks and tiny, BB-size spheres which scientists dubbed "blueberries."
Geologists recognized the pocks as "vugs," or cavities left in rocks after the erosion of fragile salt crystals. The crystals first formed in the porous rock as the ground water evaporated. The spheres, they said, are hematite "concretions," formed as salty ground water evaporates and dissolved minerals come out of solution.
Last week, geologists said Opportunity had found sedimentary rocks that contained evidence of rippling in Martian sediments. Such rippling is caused by flowing water.
After 58 days on Mars, Opportunity had answered the central question the $840 million mission was designed to resolve: "This was a shallow sea very suitable for life," said Steven Squyres, science team leader for the Mars rovers.
