The accepted view of Mars is red rocks and craters as far as the eye can see. That’s much what scientists expected when the rover Perseverance landed in the Jezero Crater, a spot chosen partly for the crater’s history as a lake and as part of a rich river system.
But what the rover found once on the ground was startling: Rather than the expected sedimentary rocks — washed in by rivers and accumulated on the lake bottom — many of the rocks are volcanic in nature. Specifically, they are composed of large grains of olivine, which are green in colour ( Science).
The rocks and lava the rover is examining on Mars are nearly 4 billion years old. Rocks that old exist on Earth but are incredibly weathered and beaten, thanks to Earth’s active tectonic plates as well as the weathering effects of billions of years of wind, water and life. On Mars, these rocks are pristine and much easier to analyse and study.
Understanding the rocks on Mars, their evolution and history, and what they reveal about the history of planetary conditions on Mars help researchers understand how life may have arisen on Mars and how that compares with early life and conditions on ancient Earth.
Scientists can use conditions on early Mars to help extrapolate the environment and conditions on Earth at the same time when life was beginning to arise. Understanding how, and under what conditions, life began will help scientists know where to look for it on other planets and moons, as well as lead to a deeper understanding of biological processes here on Earth.
The search for life is one of Perseverance’s main goals and one of the reasons it landed in Jezero Crater in the first place.