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Friday, May 20, 2022

Martian buried lakes may very well simply be clay

This picture taken by NASA’s Mars Reconnaissance Orbiter exhibits ice sheets at Mars’ south pole. The spacecraft detected clays close by this ice; scientists have proposed such clays are the supply of radar reflections which were beforehand interpreted as liquid water. Credit score: NASA/JPL-Caltech/College of Arizona/JHU

The place there’s water, there’s life — however Mars will not be as watery as we thought. We already knew that liquid water can’t actually final on the floor: it might evaporate very quickly. We additionally knew that water ice is plentiful in some areas on Mars. However what about liquid water?

Based mostly on observations in 2018, astronomers began to suspect that Mars could have underground lakes beneath some lots of ice. This was primarily based on observations from a radar instrument aboard the ESA (European Area Company) Mars Categorical orbiter.

The concept isn’t as loopy because it sounds. Earth additionally has a variety of underground water, and even frozen moons like Europa or Ganymede are thought to have massive lots of subsurface water. Mars having a subsurface lake beneath its ice cap wouldn’t be all that bizarre — particularly as the info appeared to again it up.

However the knowledge could not again it up in spite of everything.

The south pole on Mars — frozen, however perhaps not as wealthy in subsurface water. Picture credit: ESA.

Radar devices ship out pulses of electromagnetic waves; the wave passes by totally different supplies (on this case, the layers of Mars), and primarily based on the electromagnetic properties of the fabric, a receiver captures the mirrored waveform.

The preliminary evaluation of this radar knowledge confirmed some robust reflections, which researchers interpreted as our bodies of water. However in a brand new examine, Isaac Smith of Toronto’s York College now has a special concept.

Smith didn’t go to Mars or something like that — he labored in a lab, freezing clays with liquid nitrogen, till they reached temperatures like these on Mars.

Isaac Smith of Toronto’s York College bundled up whereas working in a lab, freezing smectite clays with liquid nitrogen to check how they reply to radar indicators. The outcomes have challenged the speculation that subsurface lakes may be discovered at Mars’ south pole.
Picture credit: York College/Craig Rezza

“The lab was chilly,” Smith stated. “It was winter in Canada on the time, and pumping liquid nitrogen into the room made it colder. I used to be bundled up in a hat, jacket, gloves, scarf, and a masks due to COVID-19. It was fairly uncomfortable.”

The clays on this case are referred to as “smectites” — a kind of rock shaped by liquid water very long time in the past. He then subjected them to radar devices much like these used on Mars, to see their response. It was precisely like what the Mars Orbiter noticed.

In a latest paper revealed in Geophysical Analysis Letters, researchers discovered that most of the “water” indicators got here from areas near the floor, the place it must be too chilly for water to stay liquid, even when blended with minerals generally discovered on Mars (that may decrease freezing temperature of water).

The coloured dots characterize websites the place shiny radar reflections have been noticed by ESA’s Mars Categorical orbiter at Mars’ south polar cap. Such reflections have been beforehand interpreted as subsurface liquid water, however their prevalence and proximity to the frigid floor recommend they could be one thing else. Picture credit: Credit: ESA/NASA/JPL-Caltech.

So we all know that it’s in all probability too chilly for liquid water to exist in these areas, and we now have one other doubtless candidate that could possibly be liable for the sign. Though it’s not but doable to instantly affirm whether or not what was on the radar knowledge was liquid water, smectites, or perhaps even one thing else, water is wanting much less and fewer doubtless.

However it is a win for science. In the end, the truth that researchers are capable of derive a lot details about a special planet, working with so little knowledge, is exceptional.

“In planetary science, we regularly are simply inching our means nearer to the reality,” stated Jeffrey Plaut of NASA’s Jet Propulsion Laboratory. “The unique paper didn’t show it was water, and these new papers don’t show it isn’t. However we attempt to slender down the probabilities as a lot as doable as a way to attain consensus.”

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