Giant “beans” that are actually frozen sand dunes in the northern hemisphere of Mars have been captured in a satellite image. The image released recently by NASA ’s Mars Reconnaissance Orbiter (MRO) shows a top-down view of the frozen “legumes,” taken to help scientists determine whether conditions on the Red Planet could have sustained life long ago.
See also: Perseverance rover: Studies some of the oldest rocks on Mars
In the photo, taken in September 2022 and released to the public in December 2024, the dunes appear surprisingly still. Dunes on both Mars and Earth typically migrate as the wind picks up grains of sand from one side of a dune and drops them on the other, making deserts look like slow-moving seas. However, the bean-shaped dunes in the photo are covered in a layer of frozen carbon dioxide during the winter in the northern hemisphere of Mars. The frost prevents the wind from picking up sand, preventing the dunes from migrating until the spring thaw arrives.
Images of ice-covered dunes are helping scientists learn whether water ever existed on the planet long enough for life to evolve and survive on Mars. Even though ice is made of carbon dioxide, not water, it still affects the chances that Mars had water for long periods of time in the past.
See also: China: Will bring samples from Mars around 2031
The amount of carbon dioxide on Mars varies depending on how the planet is angled relative to the sun. Earth wobbles a little as it spins on a slightly tilted axis, and that gives us different seasons. But Mars’ axial tilt wobbles a lot over millions of years, drastically changing its seasons. When Mars tilts enough, the carbon dioxide ice turns into gas on a large scale—enough to give the entire planet a thicker atmosphere. This thicker atmosphere may have been enough to support liquid water for long periods.
See also: A NASA mission may have “killed life” on Mars
With a better understanding of how carbon dioxide permafrost comes and goes under current conditions on Mars, scientists can make better predictions about the planet's past climate. Studying how permafrost changes with the seasons can also help scientists identify geological formations caused by carbon dioxide, revealing more details about the planet's changing climate . If there were periods of time when the climate consistently supported liquid water, there's a good chance Mars also supported microbial life — and it may still be lurking somewhere.
Source: livescience
