Ever since the Opportunity and Curiosity Rovers began their research stint on the red planet, evidence has been pouring in that indicates that the planet once supported life. And now, by examining the compositions of Martian meteorites found on Earth and data provided by the Mars rovers, Scientists from the Department of Earth Sciences at the University of Oxford have determined that the planet once boasted an oxygen-rich atmosphere.
The key determinant was the fact that the Martian surface rocks were five times richer in nickel than the meteorites found on Earth, a find which cast doubt on whether the meteorites were typical volcanic products. Whilst it is possible that the geological composition of Mars varies immensely from region to region, the team believes that it is more likely that the differences arise through a process known as subduction – in which material is recycled into the interior.
The scientists suggest that the Martian surface was oxidized very early in the history of the planet and that, through subduction, this oxygen-rich material was drawn into the shallow interior and recycled back to the surface during eruptions 4 billion years ago. The meteorites, by contrast, are much younger volcanic rocks that emerged from deeper within the planet and so were less influenced by this process.
As Professor Bernard Wood, the senior author of a study that appeared in Nature magazine, put it:
What we have shown is that both meteorites and surface volcanic rocks are consistent with similar origins in the deep interior of Mars but that the surface rocks come from a more oxygen-rich environment, probably caused by recycling of oxygen-rich materials into the interior. This result is surprising because while the meteorites are geologically young, around 180 million to 1.4 billion years old, the Spirit rover was analyzing a very old part of Mars, more than 3.7 billion years old.
In addition to evidence that Mars once had a sizable amount of surface water, in the form of rivers and lakes, this latest study demonstrates that Mars was once very much like Earth. In all likelihood, it would have been home to countless forms of bacteria, single-celled organisms, and possibly larger creatures as well. But being at the edge of our Sun’s habitable zone, it was unable to maintain the conditions for life to thrive.
Sad news, but encouraging when it comes to the prospect of making Mars able to sustain life again. And in the coming years and decades, that’s precisely what a number of space agencies, private companies and citizens want to do. And if these plans are to succeed long term, the planet will have to be converted into something that can independently support life.
In short, the colonization of Mars requires that the planet become something akin to its old self.