A study published in Astrobiology on November 13 has revealed the challenges posed by cosmic radiation 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 salt-rich conditions. This adds to concerns about the preservation of biosignatures in regions on Mars that were once considered the most likely to host life.
As reported Anais Roussel, an astrobiologist at Georgetown University, highlighted the issue of salt-rich environments on Mars. Roussel stated to Space.com, that they go for salt-rich environments, but they could be one of the most damaging under radiation. These findings raise concerns about whether the surface of Mars, constantly exposed to cosmic radiation 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 the molecules degrading into smaller fragments. Comparatively, some Martian rocks, like those in Gale Crater, have been exposed to radiation for approximately 80 million years. The inclusion of salts in the samples accelerated the breakdown, suggesting a chemical reaction between radiation-induced compounds and organic molecules. The exact mechanisms driving this rapid degradation remain under investigation.
Deeper Exploration May Hold Answers
Reportedly, while existing NASA rovers, including Curiosity and Perseverance, can 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 metres. This capability could bypass much of the radiation-affected surface. In statements to Space.com, Roussel advocated for missions targeting Martian caves or lava tubes, which might offer pristine conditions. She said that it would be extremely challenging from an engineering point of view, but this increases hope.
The study emphasises the importance of revisiting exploration strategies to account for the limitations posed by radiation and environmental factors on Mars.