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Mars geology in Gale Crater
This schematic illustrates how the creation and disappearance of a Martian lake created different layers of rock in the region being explored by NASA’s Curiosity rover. (NASA / JPL Graphic)

Scientists say they’re putting together the puzzle pieces provided by NASA’s Curiosity rover to get a better picture of how the outlook for habitability on Mars brightened and dimmed over the course of billions of years.

“We see all the properties in place that we like to associate with habitability,” Caltech planetary scientist John Grotzinger said today during a session at the American Geophysical Union’s fall meeting in San Francisco.

As Curiosity makes its way up the layered slopes of a 3-mile-high peak known as Aeolis Mons or Mount Sharp, it’s encountering different layers of material that hint at how the region around the mountain was formed.

Grotzinger and his colleagues said that clay minerals, boron and an iron-bearing mineral known as hematite are more abundant in the higher layers. Their presence suggests that there was dynamic chemical interaction between the rocks and groundwater in ancient times.

“The more complicated the chemistry is, the better it is for habitability,” Grotzinger explained in a NASA news release. “The boron, hematite and clay minerals underline the mobility of elements and electrons, and that is good for life.”

Boron is particularly interesting because it’s thought to play a role in building RNA molecules. Traces of the element have been found in a Martian meteorite that fell to Earth, but Los Alamos National Laboratory’s Patrick Gasda said Curiosity made the first detection of boron on Mars itself.

The patterns of rock layers, and the veining of minerals within them, are consistent with scientists’ view that the rover’s locale in Gale Crater was once the basin of an ancient watershed.

As the groundwater circulated, it drove chemical reactions that dissolved some minerals and deposited others. Eventually the water evaporated, leaving behind sediments that turned into the mudstone, sandstone and other types of rock documented by Curiosity.

Members of the Curiosity team from NASA’s Jet Propulsion Laboratory said the rover was generally in good health, more than four years after its touchdown on Mars. However, project scientist Ashwin Vasavada said engineers were working through a problem with a motor that moves the rover’s drill.

Engineers thought they had come up with at least a partial fix for the problem earlier this month, but found out “that problem is recurring,” Vasavada said. The rover is staying put while efforts to revive the drill continue, he said.

Watch the whole session on video, courtesy of the American Geophysical Union:

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