by A European Space Agency (ESA) probe has found enough water to cover. Mars in an ocean between 4.9 and 8.9 feet (1.5 and 2.7 meters) deep, buried in the form of dusty ice below the planet’s equator.
The discovery was made by ESA’s Mars Express mission, a veteran spacecraft that has been conducting science operations around Mars for 20 years now. Although this is not the first time that evidence of ice has been found near the Red Planet’s equator, this new discovery is the largest amount of water ice detected there to date and appears to be consistent with discoveries of water previously frozen on Mars.
“Excitingly, the radar signals match what we expect to see from layered ice and are similar to the signals we see from the polar caps of Mars, which we know to be very ice-rich,” the researcher said. lead Thomas Watters from the Smithsonian Institution in the United States of America in an ESA statement.
The deposits are thick, extending 3.7km (2.3 miles) underground, with a crust of hardened ash and dry dust hundreds of meters thick. The ice is not a clean block but is heavily contaminated by dust. Although its location near the equator makes it a more accessible location for future crewed missions, it means being buried so deep that accessing the water-ice would be difficult.
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About 15 years ago, Mars Express detected deposits under a geological formation called the Medusae Fossae Formation (MFF), but scientists weren’t sure what those deposits were. The geography of Mars is divided between northern highlands and southern lowlands, and the vast 5,000 km long CMA lies close to the boundary between the two.
It is suspected that the CMA itself was formed in the last 3 billion years from a lava flow and was covered by volcanic ash during a long ago period when Mars was volcanically active. Today, the CMA covered in a pile of dust rising several kilometers high – it is the most abundant source of dust on the entire planet, fuel for the giant dust storms can engulf Mars on a seasonal basis. Were the deposits just dust, perhaps filling a deep valley?
New observations from MARSIS, a subsurface radar on board Mars Express, now have the answer – and it’s not dust.
“Given its depth, if the CAI were just a giant pile of dust, it would be expected to compact under its own weight,” Andrea Cicchetti of Italy’s National Institute of Astrophysics said in a press release. “This would create something much closer than what we actually see with MARSIS.”
Instead, the deposits are low in density and relatively transparent to the MARSIS radar, which is exactly what water ice would be expected to show in the data.
More relevant is the question of how the water ice was placed at the equator. Subsurface ice has previously been found in large quantities on Mars; NASA’s Phoenix mission dug up ice just below the dust surface at the lander’s polar landing site in 2008. Meanwhile, early in its mission, Mars Express detected a lot of water ice extending down to mid-latitudes, and NASA. Mars Odyssey There were even hints of the presence of water in the CMA in 2009.
Later, ESA’s Trace Gas Orbiter hydrogen detected from water ice just below the surface of Candor Chaos, which is part of the huge crater on the surface of Mars that we call Vallis Marineris. In addition, the remains of ancient glaciers, called remnant glacierswho saw in the East Noctis Labyrinthuswhich is exactly 7.3 degrees south of the equator.
The presence of subsurface water ice at low and equatorial latitudes suggests that the climate of Mars was very different in the distant past.
“This latest analysis challenges our understanding of the MFF and raises as many questions as answers,” said Colin Wilson, ESA’s Project Scientist for Mars Express and the Trace Gas Orbiter, in the statement. “How long did these ice deposits form, and what was Mars like at the time?”
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The ice may have been there as a result of Mars’ nomadic axis. Throughout the Red Planet’s history, the axial tilt of the planet’s poles is understood to have varied comfortably. Currently the poles of Mars are tilted to the ecliptic by 25 degrees (compared to Earth, which has a tilt of 23 degrees) but in the past this could have ranged from an angle as shallow as 10 degrees, to to angles as extreme as 60 degrees. .
During periods of high obliquity, when the poles are pointing closer to the sun than the equator, water-ice may form in large quantities on the surface at the equator. That ice could then be buried with ash and dust falls, to remain covered to this day.
The variable obliquity could also explain features 400,000 years old the Chinese rover Zhurong discovered on Marsas well as the have gutters made by liquid water where such water should not exist.
The new discovery is described in a paper published in Geophysical Research Letters.
