Carbon dioxide rivers? Ancient Mars liquid may not all have been water
For decades, evidence like massive outflow channels, ancient river valleys, deltas and lakebeds have suggested Mars had a watery past, as these formations resemble those shaped by water on Earth. These widespread features would seem to narrow the possibilities to liquid water — but there are cracks in this theory.
Another possibility is liquid carbon dioxide. Under the dense atmosphere of early Mars, carbon dioxide could have liquefied and plausibly flowed across the Red Planet, carving its surface in ways similar to water. In a new study, a team of researchers argue that our extensive understanding of water-based systems on Earth, combined with limited knowledge of liquid carbon dioxide systems, may have led us to prematurely dismiss a scenario that could have fundamentally shaped Mars as we know it today.
"It's difficult to say how likely it is that this speculation about early Mars is actually true," said Michael Hecht, principal investigator of the MOXIE instrument aboard the NASA Mars Rover Perseverance, in an interview with MIT News. "What we can say, and we are saying, is that the likelihood is high enough that the possibility should not be ignored."
