Beneath Canyons on Mars, Astronomers Find Potentially ‘Water-Rich Area the Size of the Netherlands’

A Martian orbiter located a large reserve of hydrogen in a mountainous area of the Red Planet

An image of the Valles Marineris on planet Mars. The region is as large as the United States and the biggest canyon in the Solar System. The region looks red and arid.
A region within Mars's Valles Marineris (pictured) called the Candor Chaos had a large amount of hydrogen about a meter below the surface. European Space Agency

Located below the Red Planet's equator, the Valles Marineris is one of the largest known series of canyons in the solar system. About a meter beneath the valley's surface, astronomers have now detected a large amount of hydrogen, reports Michelle Starr for Science Alert. The discovery, published in the journal Icarus, may allow future astronauts to access water on Mars easily.

While water has been previously known to exist on Mars, most of it is found as ice caps near the poles. Water and ice have never been found at the surface near the equator, however, because temperatures are not cold enough for it to be stable, per a statement. Other missions have looked for surface water hidden as ice on dust particles or locked within minerals.

Researchers at the European Space Agency and the Russian Space Research Institute found evidence of water underneath the cosmic tectonic fracture using the ESA-Roscosmos ExoMars Trace Gas Orbiter (TGO) probe, reports Alex Wilkins for New Scientist.

A map of water rich regions on Mars
ESA's ExoMars Trace Gas Orbiter probe mapped the most amounts of water in the deep valleys of the Candor Chaos region on Mars shown in purple and marked as C on the map. The areas shown in purple have the highest concentration of water.
  I. Mitrofanov et al. (2021)

Launched in 2016, TGO detected and mapped hydrogen in the top meter of Martian soil using an instrument dubbed Fine Resolution Epithermal Neutron Detector (FREND), reports Meghan Bartels for By detecting neutrons instead of light, the instrument peers through the Red Planet's dust to search for water reservoirs not picked up by other equipment. FREND can measure the hydrogen content of Mars' soil up to a meter below the surface, Science Alert reports.

"Neutrons are produced when highly energetic particles known as 'galactic cosmic rays' strike Mars; drier soils emit more neutrons than wetter ones, and so we can deduce how much water is in a soil by looking at the neutrons it emits," says co-author Alexey Malakhov, a sceintist at the Space Research Institute of the Russian Academy of Sciences, in a statement.

ExoMars 2016 arriving at Mars (without annotation)

Using TGO's data from May 2018 to February 2021, the team found a large amount of hydrogen beneath the surface of Mars' version of the Grand Canyon, called Candor Chaos. If all of that hydrogen is bound into water molecules, a subsurface region about the size of the Netherlands could be about 40 percent water, explains the study's lead author Igor Mitrofanov of the Space Research Institute of the Russian Academy of Sciences, who is principal investigator of FREND, in a statement

"We found a central part of Valles Marineris to be packed full of water — far more water than we expected," Malakhov said in a statement. "This is very much like Earth's permafrost regions, where water ice permanently persists under dry soil because of the constant low temperatures."

The water, however, does not appear as abundant liquid lakes found on Earth. Instead, scientists suspect the Martian dust is riddled with ice or water bonded to minerals, CNN's Ashley Strickland reports. Minerals in this region, however, are not know to contain much water. While ice may seem more likely based on what researchers know about other potential sources of hydrogen on Mars, the temperatures and pressure conditions in the Valles Marineris, situated just below the Martian equator, prohibit the formation of these types of water preserves, Science Alert reports.

There may be special geologic conditions that allow the water to be replenished and remain in this region, CNN reports. Researchers plan on deciphering what type of water lies within the canyon's grooves and how it remains by planning future missions that will focus on lower latitudes in this region.

"Knowing more about how and where water exists on present-day Mars is essential to understand what happened to Mars's once-abundant water, and helps our search for habitable environments, possible signs of past life, and organic materials from Mars's earliest days," says ESA physicist Colin Wilson in a statement.

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