Author: Lisa Grossman / Source: Science News
Some signs of water on Mars may have just dried up.
Thanks to the way data from NASA’s Mars Reconnaissance Orbiter are handled, the spacecraft may be seeing signs of hydrated salts that aren’t really there, planetary scientists report online November 9 in Geophysical Research Letters.
That lack of salts could mean that certain sites proposed as places where life could exist on Mars today, including purported streaks of liquid water on the walls of Martian craters, are probably dry and lifeless.
“People think these environments might be inhabitable by microbes,” says planetary scientist Ellen Leask of Caltech. But “there might not actually be any real evidence for it,” at least not from orbit.
Leask and her colleagues found the problem while searching for hydrated salts called perchlorates in maps of Mars taken by the orbiter’s Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM. Perchlorates can lower the freezing point of water by up to 80 degrees Celsius, which could be enough to melt ice in the frigid Martian climate.
Both the Phoenix Mars lander (SN: 4/11/09, p. 12) and the Curiosity rover have detected tiny amounts of perchlorates in Martian soil (SN Online: 9/26/13). “Finding perchlorate was a big deal, because it’s a way to really make liquid water on Mars,” says planetary scientist Bethany Ehlmann of Caltech.
NORTHERN BRINES
To see if the salts showed up in other locations on Mars, scientists turned to CRISM’s chemical maps, which show how light reflects off of the Martian surface in hundreds of wavelengths. The resulting spectra allow scientists to identify specific minerals on the surface based on the…
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