NASA is exploring Mars with the hopes of looking for fossilized life, but the chances organisms currently exist on the Red Planet may have taken a significant nosedive, according to a new study.
What researchers once believed to be lakes of liquid water hiding under the Martian surface may actually be deposits of frozen clay.
Planetary Science Institute research scientist Isaac Smith says a new analysis of radar data from 2018 taken by the MARSIS tool on the European Space Agency’s Mars Express spacecraft delivers ‘a knockout’ to the idea liquid water exists on Mars.
What researchers once believed to be lakes of liquid water hiding under the Martian surface may actually be deposits of frozen clay
They reanalyzed radar data from 2018 taken by the MARSIS tool on the European Space Agency’s Mars Express spacecraft. Minerals know as smectites are ‘extremely abundant’ on Mars, covering nearly 50% of the surface and especially focused in the southern hemisphere
‘To date, all previous papers were only able to suggest holes in the lakes argument,’ Smith said in a statement. ‘We’re the first paper to demonstrate that another material is the most likely cause of the observations.’
He continued: ‘Now, our paper offers the first plausible, and considerably more likely, alternative hypothesis to explain the MARSIS observations. Specifically, solid clays frozen to cryogenic temperatures can make the reflections.
‘Considering the recent work on this topic finding faults with the lake theory, this is like a 1-2-3 punch combination that puts big holes in the lake interpretation and then solves the riddle.’
Given that it would take significant amounts of heat and salt to keep the water liquid at Mars’ southern ice cap, Smith says it’s more plausible that minerals known as smectites, a type of clay that’s similar to volcanic rock and are ‘extremely abundant’ on Mars is what caused scientists to initially interpret the radar readings as liquid water.
Researchers heated the smectite (pictured) in paste state at 295 K and 230 K and then cooled it to -45 degrees Fahrenheit and found at this temperature, it could generate bright radar reflections
In 2018, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) detected areas of radar evidence of a lake beneath the Martian south polar ice
The researchers cooled smectites in the lab to -45 degrees Fahrenheit. At this temperature, smectites laced with water could generate the bright radar reflections that MARSIS detected.
‘Smectites are a type of clay that is extremely abundant on Mars, covering nearly 50% of the surface, especially focused in the southern hemisphere,’ Smith explained.
‘I call them solid state to reinforce the idea that these materials are solid. There is no unbound water. Further, our experiments show that when the clays are frozen to cryogenic temperatures, they become brittle, rather than a soft clay like you might use for pottery.’
He continued: ‘Recent theoretical work had suggested that clays could make bright reflections, but no one had frozen them to temperatures we would see on Mars – namely 40 to 50 degrees below freezing – and measured them, nor had they identified these minerals at the south pole.’
The average temperature on Mars is roughly -81 degrees Fahrenheit on the average, according to NASA.
However, it can range as low as -220 degrees Fahrenheit in the wintertime at the poles to a robust 70 degrees Fahrenheit in the lower latitudes in the summer, according to the National Weather Service.
In 2018, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) detected areas of radar evidence of a liquid lake beneath the Martian south polar ice.
Two years later, researchers found several salty lakes in the area, each about six miles across.
Smith is convinced that the lakes being comprised of liquid water ‘is hard to support at this point,’ but not everyone is convinced, including NASA JPL’s Jeffrey Plaut.
‘In planetary science, we often are just inching our way closer to the truth,’ Plaut said in a separate statement.
‘The original paper didn’t prove it was water, and these new papers [Smith’s and others recently published] don’t prove it isn’t. But we try to narrow down the possibilities as much as possible in order to reach consensus.’
The new study has been published in Geophysical Research Letters.
Last month, ‘dozens’ of lakes less than a mile beneath the surface of the Red Planet were detected, according to a new study.
Scientists believe Mars holds large volumes of water but much of it is stored in ice or in brine patches
How important is the presence of liquid water?
It is now widely believed that Mars holds a reasonably large volume of water.
However, the surface of the planet is so cold, this water exists only as ice.
In order for life to exist on a planet, many scientists believe it is essential for the world to possess liquid water.
Ever since technology has enabled mankind to gaze at Mars in detail, humans have been looking for indications that there was water on the red planet.
Did water used to flow on the surface of Mars?
The Mariner 9 mission revealed clues of water erosion in river beds and canyons, as well as evidence of weather fronts and fogs on Mars in 1971.
Later missions from the Viking orbiters, which first launched in 1975, revealed yet more details about how water flowed on the surface and carved valleys.
Several studies investigated the presence of liquid water for decades. In 2000, the first proof of liquid water on Mars was discovered.
It was claimed the gullies seen on the surface of the planet had to have been formed by flowing water.
Scientists cited the debris and mud deposits left behind as evidence for moving water existing at some point in the history of the red planet.
However, the formation of these gullies has been hotly debated throughout the ensuing years.
Proof of ice in geological samples from Mars
Spirit and Opportunity, the twin rovers, found evidence of the presence of water enclosed in rock in 2007, when one of Spirit’s wheels broke and gorged a piece of stone.
Analysis of the silica-rich layer discovered in the scratch suggested it formed in the presence of liquid water.
In 2008, the Phoenix lander was gathering geological samples, and they disappeared after a few days.
Scientists thought these were pieces of ice. This assessment was confirmed when the lander later detected water vapour in a sample.
In 2012, Curiosity was meandering over an ancient martian seabed when it examined a number of rocks that were exposed to liquid water billions of years ago.
In 2012, Curiosity (pictured) was meandering over an ancient martian seabed when it examined a number of rocks that were exposed to liquid water billions of years ago
Recurring slope lineae and debate causes it
Features known as recurring slope lineae (RSL) were first identified in 2011.
These dark streaks populate the areas of Mars with a sharp incline.
Researchers speculated that these may have been caused by the intermittent flow of liquid water down steep banks on the planet.
In June 2013, Curiosity found powerful evidence that water good enough to drink once flowed on Mars. In September of the same year, the first scoop of soil analysed by Curiosity revealed that fine materials on the surface of the planet contain two per cent water by weight.
In 2015, Nasa claimed to have discovered the first evidence of liquid water on Mars in the present day.
The space agency said that its Mars Reconnaissance Orbiter (MRO) provided the strongest evidence yet that liquid water flows intermittently on present-day Mars.
In 2017, Nasa issued another statement rebuking its initial findings.
Features known as recurring slope lineae (RSL) were first identified in 2011 (pictured). These dark streaks populate the areas of Mars with a sharp incline. Researchers speculated that these may have been caused by the intermittent flow of liquid water
It said the dark features that run down steep inclines on the red planet were actually granular flows, where grains of sand and dust slip downhill to make dark streaks, rather than the ground being darkened by seeping water.
Images from the MRO revealed the streaks only exist on slopes steep enough for dry grains to descend the way they do on faces of active dunes.
Also in 2017, scientists provided the best estimates for water on Mars, claiming it once had more liquid H2O than the Arctic Ocean – and the planet kept these oceans for more than 1.5 billion years.
The findings suggest there was ample time and water for life on Mars to thrive, but over the last 3.7 billion years the red planet has lost 87 per cent of its water – leaving the surface barren and dry.
A subterranean lake
In a study published in the journal Science, ESO researchers have now discovered the first concrete evidence for liquid water on Mars.
Using radar imagery from the Mars Express probe, the ESO team have found a 12-mile long underground lake filled with liquid water.
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