Mars has sometimes had nice weather in the past

Scientists have suspected that Mars has liquid bodies of water for decades, but it was hard to say that the Red Planet has ever had “nice weather.” Until now.

The climate of young Mars was subject to intermittent periods of warmth due to an increase in greenhouse gases caused by meteorites and volcanism – between longer periods of cold – which opened up pathways for microbial life, according to a new study published in the journal Nature Geoscience.

The study’s authors-who worked under the leadership of Prof. Robin Wordsworth of Harvard University-emphasized the need to reconcile the geology of Mars with models of atmospheric evolution. This is extremely difficult because the Martian geology includes evidence of temporary reservoirs of liquid water in the past, as well as geochemistry that suggests a slow and intermittent change from wetter to drier conditions.

The researchers used a “coupled model of episodic warming, oxidation, and geochemical transformations of young Mars.” With this, they developed a new model that integrates the random release of greenhouse gases to assess the conditions responsible for the extremely diverse geological forms on the Red Planet’s surface.

– Mars was periodically warmed as its atmospheric composition was altered by gases from volcanism and meteorite impactors. These climatic optima allowed water to flow over the surface, forming rivers and lakes, as well as the rocks and minerals we associate with water on Mars, said Professor Joel Hurowitz of Stony Brook University’s Department of Geosciences.

Hurowitz is also a member of the team responsible for leading the Perseverance rover’s research, and was one of the scientists who worked on the Planetary Instrument for X-ray Lithochemistry (PIXL), which the rover’s arm is equipped with.

A newly developed climate model predicts that early Mars was generally cold, with average annual temperatures below -33.33°C. When the rate of greenhouse gas release peaked and background carbon dioxide levels rose to sufficient levels, sufficiently warm climatic periods saw the emergence of plants capable of eroding the crater wall, connecting valley networks, and creating other various fluvial (that is, lake-related) geographic features.

The researchers also explained that the model predicts a temporary accumulation of oxygen in the Martian atmosphere, which would help explain the presence of oxidized minerals such as manganese oxides that have been observed in Gale crater by the Curiosity rover. The research team also added that the large-scale temporal changes in the mineralogy of the Red Planet’s surface can be explained by three combined phenomena.

These are planetary oxidation, reduced groundwater availability, and a waning stream of meteorite impacts, which together have dramatically slowed the remodeling and thermochemical annihilation of sulfates on the Martian surface.

The new Mars climate model suggests unprecedented possibilities for the emergence of life during warm, wet periods. On the other hand, such life would be difficult to survive because of the Red Planet’s regularly occurring climate cooldowns.

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