By Xinhua,
Beijing : Hydrothermal vents similar to those found in America’s Yellowstone National Park may have carried water up through the Martian soil, according to data provided by NASA’s Spirit rover.
The site of these proposed vents could possibly contain preserved traces of ancient Martian life, scientists say. That assumes, of course, that life might once have existed on Mars. No firm evidence for that idea has ever been found, however.
The robotic explorer found deposits of pure silica, a form of the element silicon that occurs when hot water reacts with rocks (quartz is a pure silica), in Mars’ Gusev Crater in 2007. The discovery was announced briefly at the time, but scientists have now had time to fully analyze the deposits. The results are detailed in the May 23 issue of the journal Science.
The silica was found when Spirit was exploring the Columbia Hills, which rise 300 feet from the middle of the flat lava plain that fills Gusev Crater. Scientists were uncertain about just what had formed these hills.
While Spirit was parked near an area known as the Tyrone site, mission scientists used the rover’s Miniature Thermal Emission Spectrometer to look at some nearby “knobby outcrops,” said study team member Steven Ruff of Arizona State University.
“It wasn’t clear what we were seeing in the knobby outcrops because they were contaminated with dust and wind-blown soil. But I thought they might be silica-rich,” Ruff said.
Surveys of other crops showed the same hints of silica, but were likewise contaminated. That’s when the rover’s jammed right front wheel came to the rescue. As the rover was driving in reverse, its crippled wheel dug a trench behind it.
“We aimed the Mini-TES at the trench and it showed a clear silica spectrum,” Ruff said. They also analyzed the trench’s white soil with the rover’s Alpha Particle X-Ray Spectrometer which showed that the soil was more than 90 percent silica. “That a record high for silica on Mars,” Ruff said.
The team eventually found silica deposits in many other places nearby. Because hydrothermal vents on Earth harbor life, scientists suspect that they may once have done so on Mars. And the trace could be left in the silica deposits.