Here's what Australian scientists say about liquid water on Mars

Mars seen from low-elevation orbit by NASA’s Viking 1 spacecraft.

The scientific community in Australia is excited by research suggesting the dark streaks which seasonally appear and fade away on the surface of Mars are caused by running, salty water.

Jonathan Clarke, president of the Mars Society Australia, says the announcement is further confirmation of what has been suspected for some time.

And this means that astronauts will have a source of water to help them survive on the surface of the red planet.

The seasonal release of water to form dark streaks on steep slopes, perhaps by salts through a process called deliquescence, or by melting of seasonal ice, provides potential habitats for microbes.

“This makes these areas an important target for any future mission to search for life on Mars,” says Dr Clarke.

“Possible liquid droplets forming round salty soil particles were seen on the legs of the Phoenix spacecraft during its mission to the Martian Arctic in 2008.

“As well as being a potential habitat for Martian life, such water-rich salts could, with appropriate planetary protection, also serve as a water source for human-crewed expeditions to the Martian surface.”

Geraint Lewis, professor of astrophysics at the University of Sydney, says many questions remain, including the source of the briney water, be it locked up ice under the surface or rarified vapours in the atmosphere.

“But this new result bolsters the argument for water on the surface of our planetary companion,” he says.

These dark, narrow, 100 metre streaks called recurring slope lineae flowing downhill on Mars are inferred to have been formed by flowing water. Image: NASA/JPL/University of Arizona

Alan Duffy, a research fellow at the Centre for Astrophysics and Supercomputing at Swinburne University of Technology, says NASA is guided in its science by following the water — where there’s liquid water there’s life.

“The brine on Mars might not directly support life but it suggests that the arid world isn’t as dry as once thought,” Dr Duffy says.

“We can’t tell if there’s life there yet but these dark streaks can tell us where to search in future.”

Eriita Jones, a postdoctoral researcher at the University of South Australia, says an observation of salty liquid water flowing across the Martian surface is extremely significant.

“Liquid water is not stable on the Martian surface in the present day, due to the low atmospheric pressure and cold temperatures,” says Dr Jones.

“Water ice is the dominant phase of water observed on Mars, but even this is restricted to near polar latitudes where the surface temperatures are cold.”

This new evidence suggests that liquid water accumulates tens of centimetres beneath the Martian surface, and to eventually grow to sufficient volumes that it leaks and flows down slope.

“The new results may indicate that currently the low latitudes of Mars may have subsurface water environments that would be habitable to microbial life,” she says.

Alice Gorman, a lecturer in space archaeology at Flinders University, has a warning about contaminating water on Mars.

She says the discovery of the salty, seasonal flows on a planet thought of as nearly dead dramatically increases the chances it might support life.

“But to get close enough to the flows to sample them, we also risk introducing terrestrial micro-organisms,” Dr Gorman says.

“We know bacteria from Earth have made it into orbit on spacecraft. This discovery means that future Martian surface missions are going to have to adhere to an even higher standard than is already the case.”

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