March 6, 2005
Happy Hunting Grounds on the Red Planet
While most planetary scientists believe water on Mars is the best clue to finding interesting rock samples, there are big questions that remain about where exactly that water may be found. New results give a short-list for some who track the water history on the red planet.
Astrobiology Magazine -- Mars Express, Europe's first mission to the Red Planet, has generated a slew of new data about the mineral composition of the planet's dry, dramatic surface. In six new papers published online by the journal Science, an international team reveals clues about the planet's past hidden in the rock.
Brown University geoscientist John Mustard co-authored three of the Mars papers, currently published on the Science Express Web site. Mustard said this research shows areas that contain water or may have otherwise been amenable to life forms millions of years ago.
"If you want to resolve the big question about life on Mars, you want to go to the right places and get samples," Mustard, associate professor of geological sciences, said. "The new research tells us where some of those places may be."
Mustard is part of a French-led team studying data from OMEGA, a spectrometer aboard Mars Express that uses visible and infrared light to map the surface composition of the planet.
Using the OMEGA data:
- Researchers found a diverse and complex mix of surface materials: silicates, ices and frosts, and hydrated minerals and sediments. Some areas, such as Terra Meridiani, where the Opportunity rover now operates, were rich in acidic sulfates. Rocks in other places, for example around the Syrtis Major volcanic plateau, were richer in clay and hydrated minerals. These are more neutral in pH, and thus more likely to support life.
- Researchers found kieserite, gypsum and polyhydrated sulfates - all sulfate minerals that contain water in their crystal structure - in canyons and buttes around the planet. Mustard said this shows that water was common and widespread during the first billion years of Mars' roughly 4.6-billion-year history. These minerals were even found inside Valles Marineris, the largest canyon in the solar system.
- Researchers found the rock-forming mineral olivine as well as low- and high-calcium pyroxene across the Mars surface. Scientists expected to find hydrated minerals in the northern lowlands because of a theory that an ancient ocean once covered these rolling plains. But OMEGA data showed that the northern lowlands are composed of volcanic rock not altered by water, making the ocean theory less likely.
Based on these findings, Mustard said Syrtis Major, Valles Marineris and Terra Meridiani would all be strong candidates for rock and soil sampling for future Mars missions.
Mustard has designed a next-generation spectrometer that will be on board the Mars Reconnaissance Orbiter, which NASA plans to launch in August.
On the Net: