What does discovery of liquid water on Mars actually mean?

Cristina Cross
July 29, 2018

Associate Professor Alan Duffy, lead scientist of Australia's science Channel, said the ending of Total Recall where Arnold Schwarzenegger melted vast ice reserves just became less science fiction and more science fact.

Given that the ghostly shadows of Mars' watery past cover the planet, the existence of liquid water beneath its surface had always been suspected by scientists.

Salts in the lake are believed to have kept the water - which has a temperature as low as -68C (-90F) - from freezing over.

Previously, there has been some suggestions about water on Mars, like droplets of water condensing on the Phoenix lander or as the possible cause of recurring slope lineae, which are seasonal dark streaks on Martian slopes.

Chevrier's work, funded by NASA, has involved studying the effects of salt on the stability of liquid water under conditions like those on Mars.

The possibility of life on Mars, either now or historically, is still the greatest question left to answer about our nearest planetary neighbour, and it will now be up to future missions - such as the current European-Russian ExoMars orbiter and future rover - to analyse it up close.

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"On Earth, it's nearly a given that if a ground-penetrating radar spots stronger reflections from the sub-surface than from the surface of the polar ice, then you are seeing liquid water".

"In Antarctica the water can exist because the temperatures below the kilometer-thick ice can reach melting point."

MARSIS now has generated roughly 13 years of data, including multiple passes over the polar regions.

Astronomers used radar data from the orbiting European spacecraft Mars Express to find the water. It sent radar pulses through the surface and polar ice caps and measured how the radio waves reflected back to Mars Express.

"If there is actually a substantial liquid water reservoir or aquifer of some sort, I think that definitely increases the chances of life on Mars - bacterial or microbial life", said Mickol, now a postdoctoral fellow doing research at the Naval Research Laboratory in Washington, D.C.

For their study, they would ideally use the radar signal to measure the material properties of the layer, which would determine how well radar signals could travel through it. The radar cross section has been tilted 90°. "This is something that is to us the tell tale sign of the presence of water", says Prof Orosei. MARSIS is a low-frequency radar and altimeter that features operation altitudes up to 800 km above the Martian surface for subsurface sounding and up to 1200 km for ionospheric sounding. "What helped the liquid water to be stable?" And if you try the same technique on areas outside the highly reflective ones, it produces values that are similar to those of dry volcanic rock on Earth.

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