Mars as seen by NASA’s Hubble Space Telescope on July 18, near its closest approach to Earth since 2003. (NASA / ESA / STScI)

Modern-day Mars may be more hospitable to oxygen-breathing life than previously thought.

A new study suggests that salty water at or near the surface of the red planet could contain enough dissolved O2 to support oxygen-breathing microbes, and even more complex organisms such as sponges.

“Nobody thought of Mars as a place where aerobic respiration would work because there is so little oxygen in the atmosphere,” said Vlada Stamenković, an Earth and planetary scientist at the Jet Propulsion Laboratory who led the work. “What we’re saying is it is possible that this planet that is so different from Earth could have given aerobic life a chance.”

As part of the report, Stamenković and his coauthors also identified which regions of Mars are most likely to contain brines with the greatest amounts of dissolved oxygen. This could help NASA and other space agencies plan where to send landers on future missions, they said.

The work was published Monday in Nature Geoscience.