Cosmic rays could wipe out signs of life on Mars, research shows

A study published in Astrobiology on November 13 has revealed the challenges cosmic rays pose in preserving potential traces of life on Mars. Researchers simulated the effects of cosmic rays on lipids, crucial molecular structures found in cell membranes. The findings indicate that lipids deteriorate rapidly when exposed to radiation, especially in high-salt conditions. This adds to concerns about the preservation of biosignatures in areas of Mars once considered the most likely place for life.

As reported, Anais Roussel, an astrobiologist at Georgetown University, highlighted the issue of Mars’ salt-rich environments. Roussel told Space.com that they choose salt-rich environments, but under radiation they could be among the most damaging. These findings raise questions about whether Mars’ surface, which is constantly exposed to cosmic rays due to the absence of an atmospheric shield, can protect molecular evidence of ancient life.

Salt and radiation: a double threat

Research indicated that lipids exposed to simulated cosmic rays deteriorated significantly within the equivalent of three million years, with up to half of the molecules breaking up into smaller fragments. By comparison, some rocks on Mars, such as those in Gale Crater, have been exposed to radiation for about 80 million years. The incorporation of salts into the samples accelerated the degradation, indicating a chemical reaction between radiation-induced compounds and organic molecules. The exact mechanisms driving this rapid degradation are still under investigation.

Deeper exploration may yield answers

While existing NASA rovers, including Curiosity and Perseverance, can reportedly only drill to shallow depths, the European Space Agency’s Rosalind Franklin Rover, scheduled for launch in 2029, is designed to drill up to two meters. This possibility could bypass much of the radiation-affected surface. In statements to Space.com, Roussel advocated missions targeting Martian caves or lava tubes, which could provide pristine conditions. She said it would be a huge challenge from a technical point of view, but this increases hope.

The study highlights the importance of revising exploration strategies to take into account the limitations imposed by radiation and environmental factors on Mars.