Washington, 3 March 2004 (RFE/RL) -- Has there ever been life on Mars? The answer, announced yesterday by U.S. scientists, is a definite "maybe."
"Our ultimate quest in Mars is to answer the age-old question -- was there life, is there life, on Mars? Today's results are a giant leap to achieving that long-term goal."
Steve Squyres, the chief scientist for a Mars exploration mission being conducted by the U.S. space agency NASA, said the purpose of the mission “was to go to Mars and see whether or not it once had habitable environments.” He says they now believe that for certain periods of time, parts of Mars could have supported life. Areas such as groundwater environments, Squyres says, are the “kind of place that would have been suitable for life."
Squyres was speaking at a Washington news conference in which NASA announced that "Opportunity" -- one of two robotic rovers currently exploring Mars -- has found evidence that the planet was once drenched in water and could have supported some forms of life.
"Now, that doesn't mean life was there,” he says. “We don't know that. But this was a habitable place on Mars at one point in time."
"Opportunity" landed on Mars on 24 January in a small crater in a vast area near the planet's equator called the Meridiani Planum. The rover has since spent most of its time studying finely layered bedrock in the crater's wall and beaming images back to NASA.
The rover also conducted chemical analyses of the outcropping, including a rock nicknamed El Capitan. In it, scientists found a concentration of sulfur rich in magnesium, iron, and other sulfate salts. The rover also detected jarosite, an iron sulfate mineral. On Earth, such minerals form in water, while the presence of jarosite is often found in acid-rich lakes or hot springs.
John Grotzinger, a NASA geologist from the Massachusetts Institute of Technology, says other evidence of water includes three visual observations -- the presence in El Capitan of small voids called "vugs," as well as round particles called spherules and the rock's own pattern of layering.
Coupled with all this is a shiny gray mineral called hematite, which on Earth is formed in water. NASA says the clues, taken together, all point to one conclusion -- the onetime presence of extremely salty water, of a density and makeup similar to that in the Dead Sea between Israel and Jordan.
The scientists say it remains unclear whether the rocks lay under a pool of water, such as a lake or ocean, or whether they percolated in water shot up from the ground, such as a spring. Nor is it clear, says NASA scientist Jim Gavin, how much of Mars may have been covered in water.
"We have a lot of questions. How extensive is this outcropping material? Are there other examples of it on Mars? Is Meridiani the one place where we had this window into that record book of Mars where it tells us about this maybe ancient groundwater environment, or are there others?" Gavin said.
Grotzinger says the vugs were probably created by crystals of salt minerals that disappeared and left centimeter-long voids in El Capitan.
The spherules -- tiny round particles -- could have been formed by meteor impacts or volcanic explosions. But they can also precipitate from liquid in porous rock. And since the spherules appear randomly, scientists concluded that they probably formed in water.
Then there are El Capitan's layers. The scientists say their pattern is called cross-bedding and is typically caused by water or wind action.
NASA says more will be known when a mission can be sent to Mars to bring rocks back to Earth. Gavin says NASA hopes to be able to do that over the next decade or so.
"We would hope to [be able to] implement a landed vehicle, not unlike the rovers, that would use a roving vehicle to collect the samples of outcrops like the Meridiani ones, drive them up to the mother ship, and then robotically return those, after measurements on site -- return them to Earth to the Earth labs," Gavin said.
Meanwhile, NASA says "Opportunity" may soon be sent to a nearby crater to see if deeper layers of rock can be examined.
A second six-wheeled NASA rover -- called "Spirit" -- is examining another area of Mars but has yet to find anything as groundbreaking. But the scientists held out hope that "Spirit" can yet stumble upon something big.
Edward Weiler, NASA's associate administrator for space science, concluded that the latest findings -- coupled with U.S. President George W. Bush's recently stated plans for exploring Mars -- appear to augur well for further studies of the Red Planet.
"Our ultimate quest in Mars is to answer the age-old question -- was there life, is there life, on Mars? Today's results are a giant leap to achieving that long-term goal," Weiler said.
More information on the Mars missions can be found on the Internet at http://marsrovers.jpl.nasa.gov/home/index.html