Water on Mars: Large deposits found below the surface at the equator

Previous discoveries of water on Mars were limited to the poles or deep underground, but water deposits spotted near the surface at the equator could be easily accessed by future astronauts


16 December 2021

Mars Express took snapshots of Candor Chasma, a valley in the northern part of Valles Marineris, as it was in orbit above the region on 6 July 2006. The High Resolution Stereo Camera on the orbiter obtained the data in orbit number 3195, with a ground resolution of approximately 20 m/pixel. Candor Chasma lies at approximately 6? south and 290? east.

Candor Chasma is part of Valles Marineris, near the Candor Chaos region

ESA/DLR/FU Berlin (G. Neukum), CC BY-SA 3.0 IGO

A region of the Valles Marineris canyon system on Mars, one of the biggest in the solar system, appears to contain large amounts of water locked just beneath the surface, making it potentially useful for future astronauts.

This is far from the first time researchers have seen water on Mars, but previous discoveries have been concentrated at the poles or deep underground, rather than relatively accessible at the equator.

Igor Mitrofanov at the Russian Space Research Institute in Moscow and his colleagues used data from the European Space Agency’s Trace Gas Orbiter (TGO) probe, which arrived at Mars in 2016, to spot an unusually high amount of hydrogen in the upper metre of the Martian surface.

The team used the Fine Resolution Epithermal Neutron Detector instrument aboard TGO to detect changes in the level of neutron emissions at the Martian surface, finding a reduction in neutrons at the Candor Chaos region of the Valles Marineris that indicates a large amount of hydrogen, suggesting the material below the surface contains about 40 per cent water.

Though the team couldn’t tell whether the hydrogen is mainly in the form of water ice or locked up inside hydrated minerals, the unusually high percentage of hydrogen indicates that at least some would be in water ice.

“Even if it’s bounded in minerals, it’s still accessible,” says Colin Wilson, ESA’s TGO project scientist, who wasn’t involved in the research. “If you were to take some sort of mineral and then put it in an oven on your lander, it’d be quite easy to get a lot of water out of it.”

As the water appears to be so close to the surface, it could be reached by the 2 metre drill aboard ESA’s Rosalind Franklin rover, which is due to launch to Mars as part of a joint mission with Russia next year. While the rover isn’t scheduled to travel to Candor Chaos, the relatively easy access of the water could make it a good candidate for future rovers equipped with similar drills.

Journal reference: Icarus, DOI: 10.1016/j.icarus.2021.114805

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