Mars’ dry riverbeds and lake basins suggest liquid once flowed on its surface, but was it water? A new Perspectives article in Nature Geoscience proposes an alternative: liquid carbon dioxide (CO2) may have been just as likely—or even more plausible—under ancient Martian conditions.
Liquid CO2: a viable candidate
While mineral evidence on Mars often points to water, studies on carbon sequestration show that liquid CO2 can alter minerals similarly, sometimes faster. Michael Hecht, lead author and principal investigator for NASA’s Perseverance rover, explains, “There is likely no one right answer, and we are merely suggesting another possible piece of the puzzle.”
More questions than answers
The conditions tested in carbon sequestration experiments on Earth differ significantly from the cold, low-pressure environment of early Mars. To confirm whether liquid CO2 could have existed and caused similar mineral alterations, further laboratory experiments are needed under more realistic Martian conditions.
Hecht emphasizes, “It’s difficult to say how likely it is that this speculation about early Mars is actually true. What we can say, and we are saying, is that the likelihood is high enough that the possibility should not be ignored.”
A new perspective on Mars’ wet past
This theory does not rule out water as a significant force shaping Mars’ landscape. Instead, it suggests a more complex history where liquid CO2, water, or both may have contributed to the planet’s striking features. By considering alternative explanations, scientists can better understand the mysteries of ancient Mars.
Source: MIT News.
