New Planet Mars Theory Suggests An Oxygen-Rich Environment

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High concentrations of manganese oxide found on planet Mars suggests that in a previous time period, it was more like Earth than we thought.

Thanks to NASA's Curiosity rover, the space agency has learned that many of the rocks on the planet are rich with the element.

"The only ways on Earth that we know how to make these manganese materials involve atmospheric oxygen or microbes," said Nina Lanza, a planetary scientist at Los Alamos National Laboratory in New Mexico, who also led the study. "Now we're seeing manganese oxides on Mars, and we're wondering how the heck these could have formed."

According to the scientists, the manganese-rich rocks cannot form without an abundance of liquid water, as well as highly oxidizing environments. The question is, where did atmospheric oxygen come from?

Lanza and her colleagues suggested that gas began to build up on the planet after its global magnetic field shut down 4.2 billion years ago. Mars' atmosphere was once dense but after losing its magnetic field, it was pummeled by high-energy ionizing radiation, thus splitting water molecules into hydrogen and oxygen. The light hydrogen went off into space, while Mars' gravity kept the heavier oxygen.

"It's hard to confirm whether this scenario for Martian atmospheric oxygen actually occurred," Lanza said. "But it's important to note that this idea represents a departure in our understanding for how planetary atmospheres might become oxygenated."

Although atmospheric oxygen does suggest signs of life, high concentrations of the element can also just accumulate through abiotic processes. Lanza and her colleagues' theory will be difficult to prove, and until the Curiosity discovers something new, they will have to stand by it.

The study was published in the journal Geophysical Research Letters.