Friday, December 23, 2016

Boron has been Detected on Mars

Boron has been identified for the first time on the surface of Mars, indicating the potential for long-term habitable groundwater in the ancient past. This finding and others from NASA's Curiosity rover science team will be discussed in a press conference today in San Francisco during the American Geophysical Union conference.

"No prior mission to Mars has found boron," said Patrick Gasda, a postdoctoral researcher at Los Alamos National Laboratory. "If the boron that we found in calcium sulfate mineral veins on Mars is similar to what we see on Earth, it would indicate that the groundwater of ancient Mars that formed these veins would have been 0-60 degrees Celsius [32-140 degrees Fahrenheit] and neutral-to-alkaline pH." The temperature, pH, and dissolved mineral content of the groundwater could make it habitable.

The boron was identified by the rover's laser-shooting Chemistry and Camera (ChemCam) instrument, which was developed at Los Alamos National Laboratory in conjunction with the French space agency. Los Alamos' work on discovery-driven instruments like ChemCam stems from the Laboratory's experience building and operating more than 500 spacecraft instruments for national defense.

Boron is famously associated with arid sites where much water has evaporated away--think of the borax that mule teams once hauled from Death Valley. However, environmental implications of the boron found by Curiosity are still open to debate. Scientists are considering at least two possibilities for the source of boron that groundwater left in the veins: It could be that the drying out of part of Gale lake resulted in a boron-containing deposit in an overlying layer, not yet reached by Curiosity. Some of the material from this layer could have later been carried by groundwater down into fractures in the rocks. Or perhaps changes in the chemistry of clay-bearing deposits and groundwater affected how boron was picked up and dropped off within the local sediments.

The discovery of boron is only one of several recent findings related to the composition of Martian rocks. Curiosity is climbing a layered Martian mountain and finding rock-composition evidence of how ancient lakes and wet underground environments changed, billions of years ago, in ways that affected their favorability for microbial life.

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