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Scientists have found signs of abundant water in Mars' Gale Crater, long after the planet was deemed dry and inhospitable. This finding, made possible by data from NASA's Curiosity rover, challenges our understanding of Mars' changing climate and potentially habitable zones.
Overview of the Feòrachas structure, showing the geometries of the lineaments and the locations of key observations. The context map shows the path of the rover (white line). The framed map shows the orientation of the ridges. The pink diagram illustrates the orientation of these ridges (result 215°, n = 10).
Credit: NASA/JPL-Caltech/MSSS. Credit: Geology (2024). DOI: 10.1130/G51849.1
NASA's Curiosity rover, while exploring Gale Crater and the northern slope of its central mountain, Mount Sharp, collected images of sediment layers indicating the action of water. These structures, formed in what is now a desert of sand, reveal the presence of water in the form of pressurized liquid, ice, or brine, much more recent than previous estimates suggested.
Gale Crater, a basin with a diameter of 96 miles (154 km) located just south of the Martian equator, was once a lake, indicating a Mars rich in water before becoming the desert world we know today. This discovery suggests that water was, in fact, still abundant but close to the surface of Mars, towards the end of the Hesperian period, between 3.7 and 3.0 billion years ago.
This finding has implications for the search for signs of life beyond Earth, potentially extending the period during which Mars could have been habitable. Desert sand formations, such as the Stimson formation, were considered less promising targets in the quest for biosignatures, or evidence of primitive life. However, the presence of structures formed by water in the sediments changes this perspective.
Future exploration of Mars could, therefore, focus on such formations to discover new clues about the planet's ability to support life. Despite the current absence of signs of life on Mars, this discovery underscores that water, a crucial element for life as we know it, persisted on Mars much longer than we thought.