Hopes of finding liquid water on Mars are fading , according to a team of NASA scientists who predict that what was once thought to be a large lake under the south pole is likely nothing more than a dusty mirage.
In 2018, the European Space Agency’s Mars Express spacecraft detected bright reflections beneath the ice cap that seemed to indicate a 20-kilometer-wide lake of liquid water. But a new study shows that the signal could simply indicate iron-rich volcanic rocks beneath the ice.
Although the radar signal was quite promising, it did not agree with the possibility that the Martian climate could support a lake like this.
“We don’t understand how there could be liquid water there, because it wouldn’t have enough energy and pressure to melt water on Mars, even if the water were salty,” says Cyril Grima, from the University of Texas at Austin and leader of the work that collects the Geophysical Research Letters journal.
Mars, a dusty and windy planet and has frozen water locked up at the poles. But how much water there might actually be below the planet’s surface is still unknown. The amount of Martian water that once existed and could exist today could provide valuable information for our understanding of life and the possibility of life on Mars.
The truth is that it is difficult to do science on another planet.
Using an exceptionally detailed radar map of Mars based on three years of data from MARSIS, a radar instrument launched in 2005 aboard the European Space Agency’s Mars Express, the team superimposed an imaginary global ice sheet on the entire planet, looking for features that might produce radar signals consistent with those from the pole if they were similarly buried under thick ice. The results were overwhelming: the reflective signals that had held the promise of water were scattered across the surface, at all latitudes. In as many as could be confirmed, they matched the locations of known volcanic plains.
This study is a sobering lesson in the scientific process, showing that it is as relevant to studying Earth as it is to Mars, and that it is not foolproof on the first try.
Referencia: The Basal Detectability of an Ice-Covered Mars by MARSIS Geophysical Research Letters.
C. Grima, J. Mouginot, W. Kofman, A. Hérique, P. Beck
First published: 24 January 2022
https://doi.org/10.1029/2021GL096518
