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One of the deepest similarities between Earth and Mars, which makes it a prime target for research and exploration, is the presence of water ice on its surface (mainly in the form of of its polar caps). But perhaps even more interesting is the presence of glaciers beneath the surface, which scientists have speculated on well before their presence is confirmed.
These underground water caches could tell us a lot about Martian history and could even be an invaluable resource if humans ever decided to install Mars on their land. According to a recent study by two scientists from Texas universities in Austin and Arizona, layers of ice beneath the northern polar ice cap may be the largest reservoir of water on the planet.
The results were the subject of a study recently published in Geophysical Research Letters. The study was led by Stefano Nerozzi, a graduate student from the University of Texas at Austin Institute of Geophysics (UTIG) and was assisted by Professor Jack Holt of the Lunar and Planetary Laboratory (LPL) at the University of Arizona.
As part of their study, Nerozzi and Professor Holt relied on data collected by the Shallow Radar instrument (SHARAD) aboard the Mars Reconnaissance Orbiter (MRO), capable of penetrating up to 2, 4 km below the surface. surface using radar waves. What they reported is the discovery of several layers of sand and ice about 1.6 km (1 mi) below the north pole of Mars.
It was found that these layers were 90% water in some places and that it was the remains of old polar ice sheets. In the event of a merger, the researchers indicate that they would create a global ocean at a depth of at least 1.5 meters (5 feet). As Nerozzi explained in a press release from UT News, this discovery was quite surprising. "We did not expect to find so much ice here," he said. "This makes it probably the third largest reservoir of water on Mars after the polar ice caps."
The results were corroborated by a separate study (on which Nerozzi was the co-author) led by researchers from Johns Hopkins University and also appeared in the Geophysical Research Letters. For this study, the team relied on gravity data to impose constraints on the density of the area below the polar ice cap. From the low density readings obtained, they estimated that the ice and sand layers contained more than 50% of the water as a whole.
This discovery is a boon to scientists because these layers are essentially a record of past climate change, and their analysis could reveal very interesting information about the planet's history. In short, the geometry and composition of these layers could help scientists determine whether the Martian climate was conducive to life.
In terms of how all this water has gotten there, the authors theorize that they were formed during previous warming and cooling periods on Mars. Scientists have known for some time that glacial events occur on Mars, which are caused by variations in the orbit and tilt of the planet (much like the Earth). Over periods of about 50,000 years, Mars sinks further towards the Sun before gradually returning to the vertical.
When Mars sits straighter, the equatorial region heats up as the northern polar region cools, pushing the ice sheets forward. When the planet tilts towards the Sun, the polar region heats up, causing the icecaps to melt. It is during these periods that the remnants of the ice caps will be covered with sand, which has historically protected them from exposure to the sun and their dispersion in the atmosphere.
Professor Holt, who has been a researcher at ITUU for 19 years before joining the University of Arizona in 2018, has been a co-investigator of the SHARAD science team since l 39; the arrival of the MRO to Mars in 2006. Using the data from this instrument, MRO was also able to confirm the presence of underground glaciers around the middle of the planet Mars.
"Surprisingly, the total volume of water enclosed in these buried polar deposits is about the same as any ice-water known to exist in glaciers and ice layers buried at low latitudes on Mars, and they are about the same age "
Previously, scientists thought the old ice caps had been lost, but this study reveals that the northern ice cap has survived beneath the planet's surface, arranged in alternating bands of ice and sand. This study not only contradicts this hypothesis, but also provides important new information on the ice-water exchange between the Mars poles and mid-latitudes.
The study of these glaciers could also determine whether Mars was habitable or not. As Nerozzi explained:
"Understanding the amount of water available in the world relative to the poles is important if you want to have liquid water on Mars. You can have all the right conditions for life, but if most of the water is blocked at the poles, then it becomes difficult to dispose of sufficient amounts of liquid water near the equator . "
With the increasing number of robotic missions sent to Mars, what we know about the planet has grown by leaps and bounds. And with each new discovery, the need to explore further becomes apparent. Someday, we may be able to step up these efforts by sending human astronauts, which could even pave the way for a human settlement.
And when these people arrive, the presence of underground glaciers will play a major role in their efforts.
Further reading: UT News, Geophysical Research Letters
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