The Exo Mars Trace Gas Orbiter spacecraft has found evidence of “significant amounts of water” in the Valles Marineris canyon system on the red planet. TGO is operated by the European Space Agency and Russian space agency Roscosmos.
The orbiter has an instrument on board that maps hydrogen in the upper layer of Martian soil. Data shows an unusual amount of hydrogen in Candor Chaos, a central region of Valles Marineris, indicating that as much as 40% of the near-surface material in that area could be water.
The water found in Valles Marineris might be tied up with minerals, but the researchers say it’s more likely to be in the form of ice. That leads to questions about how the water ice is preserved in an area of Mars where it would be expected to evaporate. The ESA said that this suggests that some special, as-yet-unclear mix of conditions must be present in Valles Marineris to preserve the water — or that it is somehow being replenished.