Tiny salt crevices could act as miniature 'Greenhouses' for Martian microbes

A new study suggests that on Mars, tiny salt crevices could act as miniature "greenhouses" for microbial life. The research, led by Anna Bognar, found that during the Martian day, when temperatures rise to 0℃, salts absorb moisture, creating a microenvironment where liquid water can remain trapped. The salt crystals expand and contract as temperatures fluctuate, creating microscopic fractures that trap water. This process occurs every day during the summer, allowing water to remain in the crevices at temperatures suitable for life as we know it. The crevices also provide protection from UV radiation, and in theory, could allow photosynthesis by letting in visible light.

The study found that halite (NaCl) salt crystals can contract by up to 1.6% between 150 K and 300 K, creating microscopic fractures. These fractures can trap water, which becomes liquid in the heat but cannot escape because there is no way out of the crevice. The salt also acts as a barrier against harmful UV rays, but not against higher-energy cosmic rays. The research notes that while the crevices may theoretically support life, there are still challenges, such as the salt potentially containing perchlorates, which are deadly to Earth-based life, and the crevices not sealing completely every day.

The paper published in Icarus describes how the salt crystals can trap water during the Martian night and release it during the day, creating a micro-habitat. The study highlights that while the environment is not perfect, it offers a potential niche for microbial life. The research also mentions that similar phenomena occur on Earth, with cyanobacteria living in halite rocks in the Atacama Desert. The study concludes that while it is theoretically possible for life to survive in such an environment, it is unlikely. The paper emphasizes that life "finds a way" and that the discovery could help answer the question of whether life exists on Mars.

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