Are Mars' Dark Streaks Really Evidence of Liquid Water?

Darkish streaks referred to as recurring slope lineae (RSL) emanate from the partitions of Mars' Garni Crater on this picture by NASA's Mars Reconnaissance Orbiter. These RSL are up to a couple hundred meters in size.

Credit score: NASA/JPL/College of Arizona

SAN FRANCISCO — The intriguing story of Mars' mysterious darkish streaks could have a brand new twist.

The streaks, referred to as recurring slope lineae (RSL), happen seasonally on steep, comparatively heat slopes at many places on the Pink Planet. They have been found in 2011 by scientists learning pictures captured by NASA's Mars Reconnaissance Orbiter (MRO).

Many researchers initially speculated that RSL could also be indicators of liquid water at or close to the Martian floor, and this speculation received a giant increase final yr when a examine reported that MRO had detected hydrated salts inside the streaks. [Liquid Water on Mars: The Discovery in Pictures]

The hydrated-salts discovery generated numerous pleasure, as a result of it steered that some locations on the in any other case dry Pink Planet's floor could also be able to supporting life as we all know it at present. The presence of accessible liquid water — even salty water, because the stuff inside the RSLs would doubtless be — may additionally assist efforts to ship astronauts to Mars, NASA officers have mentioned.

However it might be prudent to rein in that pleasure a bit, in line with a brand new examine. Hydrated salts are crystalline solids, and it is doable that the water the RSL salts include comes from the Martian environment reasonably than liquid water at or close to the floor, mentioned Raina Gough, a analysis scientist on the College of Colorado, Boulder.

Gough and her colleague, Margaret Tolbert, additionally of UC Boulder, carried out lab experiments to check this concept. They uncovered varied anhydrous (dry) salts to Mars-like atmospheric circumstances and located that a few of them — calcium perchlorate and calcium chloride — did certainly turn out to be hydrated. (The RSL salts on Mars seem like perchlorates of some sort, the researchers who noticed them wrote of their 2015 examine.)

These outcomes, which Gough introduced Tuesday (Dec. 13) right here on the annual fall assembly of the American Geophysical Union (AGU), do not show something; it is nonetheless very doable that liquid water is concerned within the formation of the hydrated salts inside the RSL throughout Mars, Gough confused. However that thrilling state of affairs should not be taken as a given, she added.

"Hydrated salts should not all the time proof of liquid water," Gough informed House.com on the AGU assembly.

Future lab work ought to try to find out which salts can't be hydrated through atmospheric water alone, Gough and Tolbert wrote within the new examine. Such salts, if recognized on Mars, would offer very sturdy proof for the presence of liquid water, they added.

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