Mars Scientists Intensify Search for Water Spurred on by the apparent discovery of evidence of very recent liquid water on Mars, researchers are boosting their efforts to determine whether water is flowing on the red planet's surface right now.
At the same time, new findings from the satellites and rovers studying Mars are unraveling the central role water has played in shaping the planet.
This week scientists announced a plan to use powerful imaging instruments on NASA's newest red planet spacecraft, the Mars Reconnaissance Orbiter, to focus on gullies. Sediment deposits found in such areas would unmistakably confirm the presence of water.
"We've moved it up the priority list," said Roger Phillips of Washington University in St. Louis, Missouri, a leader of the orbiter's radar team.
"We hope for results by the end of next month."
Phillips and other NASA researchers presented their new Mars findings Wednesday in San Francisco at a meeting of the American Geophysical Union.
Below the Surface
The Mars Reconnaissance Orbiter entered the planet's orbit in March. The spacecraft has already peeked below the planet's ice-covered poles, revealing complicated layers just beneath the surface.
These strata represent "a tape recorder of the climatic history of the planet," Phillips said.
The findings allow scientists to begin piecing together the planet's climate cycles as far back as hundreds of millions of years.
The orbiter has also found deposits of ancient, water-bearing clays and gypsum, added John Mustard of Brown University in Providence, Rhode Island.
Such minerals "record the history of the interaction between water and the surface of Mars," he said.
Meanwhile the European Space Agency's Mars Express spacecraft has probed beneath Mars's northern hemisphere, revealing 11 buried impact craters beneath the hemisphere's relatively smooth surface. The buried craters range from 80 miles (130 kilometers) to 290 miles (470 kilometers) in diameter.
The findings, reported in this week's issue of the journal Nature, help explain why Mars's sparsely cratered northern hemisphere differs so drastically in appearance from the southern hemisphere's craggy highlands.
The scientists speculate that the northern craters were covered up fairly recently, geologically speaking, by the smother, younger crust visible at the surface. Exactly what caused this burial remains a mystery.
NASA's twin Mars rovers, Spirit and Opportunity, are also making new finds—nearly 900 days after their original, 90-day mission was originally slated to end.
Opportunity recently completed a 21-month, four-mile (seven-kilometer) uphill trek to arrive at the edge of a large crater known as Victoria.
The rover has snapped high-resolution images of the crater's interior, revealing layers of ancient rock characteristic of windblown deposits.
It "looks just like a place on Earth," said Steve Squyres of Cornell University in Ithaca, New York, principal investigator for the rovers' mission.
Opportunity also reencountered "blueberries," tiny spherical deposits filled with minerals that typically form in the presence of water.
The blueberries were probably created in the area when subsurface water rose, reaching the surface at lower elevations, such as Opportunity's landing site, Squyers said.
But at the higher elevations Opportunity traveled on in recent months, the blueberries most likely remained below the surface. The newfound blueberries were probably flung free during the impact that created Victoria Crater.
The blueberry-forming water seems to have evaporated pretty quickly, even on the rare occasions when it reached the surface, Squyers added.
"Mostly it was an arid environment," he said.
Opportunity's twin, Spirit, is also back on the move after its second Martian winter—though it has had to travel mostly backward ever since one of its front wheels was damaged.
The rover has found water-altered minerals and basalt rocks in the Columbia Hills, an area typical of much of Mars's surface.
Spirit has also spotted water-ice clouds.
"We didn't see that last winter," said Ray Arvidson, NASA's deputy principal investigator for the rovers.
"This shows that Mars has significant interyear variability."