Mars had oxygen, water, everything. Mars had it all - but still no life

Scientists believe they have discovered evidence which shows Mars once had an oxygen-rich atmosphere about 1.5 billion years before Earth did. That means four billion years ago, the Martian atmosphere might have been more hospitable to life.

LOS ANGELES, CA (Catholic Online) - Scientists have concluded that the Martian atmosphere was rich in oxygen about 1.5 billion years before oxygen was common on Earth. They reached this conclusion after examining meteorites and rocks on the Martian surface and comparing them to those on Earth. Key differences in the rocks are best explained by shifts in the amount of oxygen in both planets' atmospheres.

Their research has been published in the journal Nature.

What's most tantalizing to consider is how oxygen may have occurred on Mars. On Earth, early microbial life consumed carbon dioxide, which was rich in the early atmosphere, and produced oxygen. Eventually, enough oxygen built up to the point that animal life became possible.

More mysterious is Mars. It is possible that chemical reactions made the early Martian atmosphere oxygen rich, but it is also possible that primitive life could have made it too. 

By applying Occam's razor to the question, it seems more logical to assume that chemical processes were responsible for the Martian oxygen; however only by means of scientific study will we be able to discern the truth.

Several studies have previously hinted at the possibility of life, but no study has ever been conclusive and the majority of studies suggest that Mars has always been sterile.

Nonetheless, as the best candidate for primitive life in the solar system, beyond Earth, the search for life continues on Mars. The prevalence of oxygen in the early atmosphere is a tantalizing mystery that suggests life could have once existed. Certainly, billions of years ago, Mars was once warmer, wetter, and had a thicker, more Earth-like atmosphere.

The prevalence of oxygen in the Martian atmosphere is also the reason why the planet is covered in reddish dust, the product of oxidization in an environment rich in oxygen and water. That reaction produces rust.

The search for life on Mars is important because if life can occur on Mars, it would suggest that life could be abundant throughout the universe. Conversely, if Mars was once hospitable, but never harbored any life, then it suggests that the processes needed to create microbial life are far more difficult to achieve without complex input.

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