Our red neighbor known as Mars has for long been depicted as a dead planet with rough conditions, not fit to support life. However, recent discoveries have shown that the dead planet might have had enormous liquid water seas, like we have here on earth.
Thanks to the Curiosity rover, now know that Mars was once a planet able to support earth-like life-forms, and even had a warmer climate than it currently does. The rover which has been roaming the red planet’s surface since August 2012 is equipped with a ChemCam instrument, which analyzes the geochemistry of rocks it stumbles upon. Curiosity has determined that the surface of the Gala crater, which it’s exploring, has high levels of manganese oxide, which indicated that there used to be high quantities of free oxygen in the atmosphere.
Even though it is hard to know how much oxygen Mars had in its atmosphere, but it is thought to have happened similarly to Earth’s Great Oxygenation Event some 2.5 billion years ago.
The Great Oxygenation Event that happened on our planet must have been started by the emergence of photosynthesizing life, like bacteria, plants and algae. Photosynthesizing life slowly absorbed the vastly abundant carbon dioxide from the Earth’s atmosphere and replaced it with free oxygen molecules. Over a period of millions of years, the levels of oxygen built up to compose about 21% of our air.
Another theory is that the oxygen could have been released when liquid water molecules started breaking down once the planed lost its gravity.
Even though the discovery might raise more questions than it answers, what is undebatable is that manganese oxide simply cannot form without extremely high quantities of free oxygen in the atmosphere, as we know from the history of our own planet.