This is the landscape that the Perseverance rover will travel over the next few years: the crater named Jezero, about thirty miles in diameter. It is estimated that it was formed about four billion years ago by the impact of a meteorite.
About three billion years ago, Mars had an atmosphere and liquid water. In fact, this crater was a lake. Five hundred million years later, the water began to disappear and the lake dried up.
On the left side of the photograph you can see the meanders created by an imposing ancient river, between five hundred meters and one kilometer wide. This river transported sediments that, when deposited, shaped a delta whose fan-shaped relief can be seen at the entrance of the lake.
Choosing the landing site
When you decide to send a rover to Mars, it is clear that the specific location is not chosen at random. It is the researchers and engineers who make the decision. Researchers prioritize the scientific interest of the area, while engineers are in charge of ensuring technical viability.
Jezero was already known from previous missions (this crater had been selected and later discarded as a Curiosity landing site), but a very precise area had to be defined to ensure a successful landing. Now new navigation techniques will be used that will allow the rover to be located in the fixed location.
The main motto of the mission is to “follow the water”, the indispensable element for all known forms of life. The choice of an ancient lake provided with a delta that an ancient river created satisfies this goal.
This enclave will also allow geological studies to be carried out and to learn more about the evolution of Mars. A sufficiently rich and diverse area had to be found. There is no doubt that heading to a totally desert area would have been much less interesting. Here, the rover can explore the bottom of the lake, the delta and even the areas less affected by the impact. In the case of Jezero, the presence of clay in the delta offers additional advantages, as this structure has the ability to absorb organic matter.
If there are fossil remains of life or, at least, of molecules that could have acted as precursors of it, there is a possibility of detecting them in the clay or nearby rocks. The main mission of the Perseverance rover will be the extraction of a few dozen samples selected with the help of on-board instruments (cameras, spectroscopic analysis, etc.). Much more accurate analysis can be done once they are back on Earth.
Michel Cabane, Emeritus Professor at the LATMOS laboratory, Pierre Simon Laplace Institute (IPSL), Sorbonne University
Este artículo fue publicado originally in The Conversation. Lea el original.
