March 2020: NASA unveiled the site where the rover will look for traces of life
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| March 2020: NASA unveiled the site where the rover will look for traces of life |
NASA has just announced that the March 2020 rover will land in the Jezero crater where the mission team is convinced that this site is home to many fossils of micro-organisms, if they existed of course. NASA has also paved the way for a mega-mission! Indeed, at the end of its initial mission, the rover will probably be directed to Midway, another site conducive to the discovery of traces of life. The interest of exploring two sites with different geological characteristics increases the scientific return; It is also a pragmatic strategy for the return of the samples that the rover will collect. Indeed, several points of collection are planned which are as many possible options for the rover which will come to recover them. Our explanations on this mega-mission with Cathy Quantin-Nataf, director of the ERC e-Mars team, in charge of the selection of the landing site of the ExoMars 2020 rover.
NASA has chosen Jezero Crater as the landing site for the rover March 2020. This rover is due to leave Earth in 2020, inside a launch window that opens July 17 and closes August 5, 2020 Its main objectives are the direct search for signs of past microbial life, collecting samples that will be recovered by another mission, and preparing for the arrival of a first inhabited mission on the red planet. His landing on Mars is scheduled for February 2021.
It will therefore land inside the crater Jezero which has an environment of interest for exobiology as well as for its geological diversity. Of the four competing sites, the Jezero crater was also the favorite of the project's scientific team. It had also proposed to Nasa a mega-mission combining not one site, but two! An unprecedented strategy made possible by the confidence inspired by Curiosity, which has been rolling for more than 6 years on the planet, and whose design of the rover March 2020 is inspired by yet additional improvements.
March 2020: two sites to maximize scientific return
Concretely, Mars 2020 will first land inside the crater Jezero then, at the end of its initial mission, will join Midway, a site that also has an environment of interest for exobiology and offers a great geological diversity. Distant about twenty kilometers from the crater Jezero, several months will be necessary to join him.
The Jezero Crater was once, about 3.5 billion years ago, a lake draining streams from a basin of about 15,000 square kilometers. Many fossils of microorganisms, if they existed, could become trapped in its clay layers. As for Midway, this site has the particularity of having geological layers, which are not the ejectas of the crater, even older than those of Jezero. They are very diverse in their composition and some are rich in olivine and carbonate. An association of materials that, on Earth, is very favorable to life.
Samples to better date the history of Mars
While they both favor the search for bio-signatures and potential proofs of a past life, Midway and Jezero have been shaped by different geological processes. A strategy that will optimize the scientific return and collection of samples by taking them from several different locations. It also has the advantage of offering several collection sites and therefore, option, for the future mission that will collect these samples to return to Earth.
If the search for an extinct form of life is the main objective of the study of these samples, dating is one of the great scientific interests of this return of Martian samples. It should be known that the ages given on Mars are established thanks to the method borrowed from the Moon and based on the number of craters per square kilometer. This method assumes that the older a land is, the more it is cratered. It made it possible to establish three major Martian periods, the Noachian, the Hesperian and the Amazonian (periods classified from the oldest to the most recent), themselves divided into sub periods. But, if it is accurate enough to date the history of the Moon, this method applied to Mars has a lot of bias. The dating error can be very important. Thus for periods of Martian history between 1 and 2 billion years, the uncertainty can be a billion years! By cons, around four billion years, this uncertainty is less (some 200 to 300 million years).
Note:
This article was written with the scientific lighting of Cathy Quantin-Nataf, professor at Lyon 1 University and researcher at the Geology Laboratory of Lyon. She is also the director of the ERC e-Mars team, in charge of the selection of the Space Agency's ExoMars 2020 rover landing site.
