Martian Recurring Slope Lineae: Transient Briny Liquid Water on Mars (poisonous to the extreme with perchlorates)

Mars may be a frigid desert, but perchlorate salts in the planet’s soil are lowering the freezing temperature of water, setting up conditions for liquid brines to form at equatorial regions, new research from NASA’s Curiosity rover shows.

The discovery of subsurface water, even a trickle, around the planets warmer equatorial belt defies current climate models, though spacecraft orbiting Mars have found geologic evidence for transient liquid water, a phenomenon termed “recurring slope lineae.”

The findings, published in this week’s Nature Geoscience, are based on nearly two years worth of atmospheric humidity and temperature measurements collected by the roving science laboratory Curiosity, which is exploring an ancient impact basin called Gale Crater near the planet’s equator.

The brines, computer models show, form nightly in the upper 2 inches of the planet’s soil as perchlorates absorb atmospheric water vapor. As temperatures rise in the morning, the liquid evaporates.

The levels of liquid, however, are too low to support terrestrial-type organisms, the researchers conclude.

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