NASA's Mars Reconnaissance Orbiter (MRO) has captured stunning images of giant frozen sand dunes in the northern hemisphere of Mars, previously mistaken for edible beans. Taken in September 2022 and published in December 2024, these images show the dunes covered with a layer of carbon dioxide frost, indicating winter conditions on the planet.
Typically, sand dunes on Mars migrate due to wind, but the presence of frost prevents this movement until spring thaw. These observations are crucial for scientists studying the planet's past, as they provide insights into whether liquid water existed long enough on Mars to support life.
While the frost is made of carbon dioxide, its behavior impacts the likelihood of historical liquid water on Mars. The amount of carbon dioxide varies with Mars' axial tilt, which has changed significantly over millions of years, affecting seasonal conditions.
During periods of greater tilt, carbon dioxide can evaporate enough to create a thicker atmosphere, potentially allowing liquid water to remain stable for extended periods. Understanding the current dynamics of carbon dioxide frost will enable scientists to make more accurate predictions about Mars' climatic history.
This research could also help identify geological formations caused by carbon dioxide, providing further details about the planet's changing climate. If there were times when liquid water was stable, it enhances the possibility that microbial life could have existed on Mars, possibly still hidden beneath its surface.