Turns out, Mars once had way more oxygen in its atmosphere than we previously thought.
A new paper has revealed that NASA's Curiosity rover observed high levels of manganese oxides in Martian rocks, which could indicate that higher levels of atmospheric oxygen once existed on our neighboring planet.
This hint of more oxygen in Mars' early atmosphere adds to other Curiosity findings, such as evidence of ancient lakes, revealing how Earth-like our neighboring planet once was.
"The only ways on Earth that we know how to make these manganese materials involve atmospheric oxygen or microbes," said lead author Nina Lanza, adding "Now we're seeing manganese-oxides on Mars and wondering how the heck these could have formed."
Microbes seem a far-fetched explanation for the manganese oxides at this point, said Lanza, but the idea that the Martian atmosphere contained more oxygen in the past than it does now seems possible.
"It's hard to confirm whether this scenario for Martian atmospheric oxygen actually occurred," Lanza added. "But it's important to note that this idea represents a departure in our understanding for how planetary atmospheres might become oxygenated." So far, abundant atmospheric oxygen has been treated as a so-called biosignature, or a sign of existing life.
The next step in this work is for scientists to better understand the signatures of non-biogenic versus biogenic manganese, which is directly produced by microbes. If it's possible to distinguish between manganese oxides produced by life and those produced in a non-biological setting, that knowledge can be directly applied to Martian manganese observations to better understand their origin.
The study appears in Geophysical Research Letters.
-With agency inputs