A team led by scientists at California Institute of Technology (Caltech) and the Jet Propulsion Laboratory (JPL) has calculated that if liquid water exists on Mars, the planet could contain more oxygen than previously thought.
According to the model, published in Nature GeoScience, the levels could even theoretically exceed the threshold needed to support simple aerobic life.
That theory goes against what was previously thought about Mars as the existence of liquid water on the red planet is not a given. Even if there was, researchers have long dismissed the idea that it might be oxygenated, given that Mars's atmosphere is about 160 times thinner than that of Earth and is mostly carbon dioxide.
"Oxygen is a key ingredient when determining the habitability of an environment, but it is relatively scarce on Mars," said Woody Fischer, professor of geobiology at Caltech and a co-author of the findings.
"Nobody ever thought that the concentrations of dissolved oxygen needed for aerobic respiration could theoretically exist on Mars," adds JPL's Vlada Stamenković, lead author of the paper.
In recent months, data from a European spacecraft has suggested that liquid water may lie beneath a layer of ice at Mars's south pole. It has also been hypothesised that water could exist in salty subsurface pools, because perchlorate salts have been detected at various places on Mars.
This is because salt lowers the freezing point of water, which means that water with perchlorate in it could potentially stay liquid despite the freezing temperatures on Mars, where summer nights on the equator can still dip down to -100 degrees Fahrenheit.
That hypothetical salty water is what interested Fischer and Stamenković. Oxygen enters water from the atmosphere, diffusing into the liquid to maintain an equilibrium between the water and the air. If salty water were close enough to the surface of the Martian soil, then it could effectively absorb oxygen from the thin atmosphere.
To find out just how much oxygen could be absorbed, the researchers developed a chemical model describing how oxygen dissolves in salty water at temperatures below the freezing point of water. They then examined the global climate of Mars and how it has changed over the past 20 million years, during which time the tilt of the axis of the planet shifted, altering regional climates.
The solubility and climate models together allowed the researchers to infer which regions on Mars are most capable of sustaining high oxygen solubilities, both today and in the planet's geologically recent past.
The team found that, at low-enough elevations and at low-enough temperatures, an unexpectedly high amount of oxygen could exist in the water - a value several orders of magnitude above the threshold needed for aerobic respiration in Earth's oceans today.
They also found that the locations of those regions have shifted as the tilt of Mars's axis has changed over the past 20 million years. During that time, the highest oxygen solubilities have occurred within the past five million years.
The findings could inform future missions to Mars by providing better targets to rovers searching for signs of past or present habitable environments, Stamenković added.
There's a new wave of automation hitting big business and the public sector, and organisations that fail to prepare or implement properly will, literally, be left for dead.
Hear from end users and other organisations about how you can effectively automate the enterprise at Computing's Automation: streamlining your essential business processes IT Leaders' Forum.
To reserve your FREE place for the event on Wednesday 7 November, check out the dedicate IT Leaders' Forum website
Some parts of Atacama have not received rainfall for 500 years - but a sudden deluge of water upset the Desert's delicate biological balance
Spitzer Space Telescope could not spot Oumuamua, suggesting that it is actually pretty small
Greenland crater one of the 25 largest impact craters on Earth
This long-sought progenitor star was identified in an image captured by Hubble in 2007