The Curiosity rover has found evidence that ancient Mars experienced a cyclical climate similar to that of Earth’s seasons, potentially increasing the planet’s past habitability.
Though Mars is now an arid and dry place, liquid water did once flow across its surface.
A day on Mars is rather similar to a day on Earth, because the planets are relatively similar, and in their ancient past were even more so.
Observations by NASA’s Curiosity rover in a region believed to have once been a lake show deposits of salt that were laid down 3.6 to 3.8 billion years ago.
The deposits are marked with a ridged pattern of hexagons.
On Earth, similar patterns are created in basins that dry out seasonally, suggesting Mars experienced wet and dry seasons in the past.
Water is one of two ingredients necessary for the emergence of life (at least as we know it) found on Mars.
The other is organic molecules which form the building blocks of life.
Curiosity and sibling rover Perseverance have both found several simple organic molecules, but for life to emerge these must first arrange themselves into more complex forms, such as RNA.
One way this can happen is by repeatedly changing the concentration of the chemicals in water.
This is something that happens in areas which dry out seasonally, meaning such salt flats could have once been the breeding ground for emergent Martian life.
