Scientists have dreamed of finding evidence for past life on Mars, where they believe there was once plenty of liquid water. But now they’re saying it might have been too salty.
“Not all water is fit to drink,” said Andrew Knoll, a Harvard University biologist who is on the science team for the NASA Mars rover Opportunity.
High concentrations of dissolved minerals as well as acids may have thwarted microbes from developing on the red planet, he added.
Opportunity and its twin, Spirit, began their fifth year on Mars last month after proving about 16 times longer-lasting than expected, according to scientists.
Mars as seen by the Hubble Space Telescope (credit: Lisa Frattare/STScI)
At a meeting of the American Association for the Advancement of Science in Boston on Feb. 15, researchers discussed the rovers’ recent discoveries.
Opportunity spent recent months examining a bright band of rocks around the inner wall of a crater in the planet’s Terra Meridiani region. The crater turned out to lie atop an underground water table, according to scientists. Knoll said the rover—which serves as a robotic geologist—found that the water, which once covered the area, left behind evidence of its high acidity and salinity.
“This tightens the noose on the possibility of life,” considering salt is a preservative, he added. Conditions may have been more hospitable earlier, with water less briny, Knoll said. But “life at the Martian surface would have been very challenging for the last 4 billion years. The best hopes for a story of life on Mars are at environments we haven’t studied yet—older ones, subsurface ones.”
Courtesy Jet Propulsion Laboratory and World Science staff