According to French researchers, the ravines on Mars were the result of the melting not of water ice, but of frozen carbon dioxide.
Just months after NASA scientists presented the most compelling evidence for liquid water on Mars, French planetary scientists questioned at least one of them.
This is reported by the journal Nature Geoscience. "The role of liquid water in gully formation must be redefined," write the authors of the article, Cédric Pilogre from the University of Paris-South (France) and his colleague François Forge from the Sorbonne (France).
Scientists in their work offer an alternative version of the origin of small channels carved into the walls of craters, hills and other protrusions on Mars. When planetary scientists first discovered the Martian ravines, they assumed that the source of their origin was melting ice or underground water leaks that occurred hundreds of thousands of years ago. However, then it was found that the formation of ravines continues, despite the temperature too low on Mars for liquid water. This allowed the researchers to assume that the planet still has reserves of liquid water.
French scientists using computer simulations have shown that ravines can arise without the participation of water flows. The authors of the article explain that the surface of Mars is covered with frozen carbon dioxide, or dry ice, which becomes much thinner closer to the equator, where it melts and turns into gas.