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On the former March, the water was digging cbads and carrying sediment to form fans and deltas in the lake basins. Examination of spectral data acquired in orbit shows that some of these sediments contain minerals that indicate chemical alteration by water. In the delta of the Jezero Crater, sediments contain clays and carbonates. (This image combines information from two Mars reconnaissance orbiter instruments, the compact reconnaissance imaging spectrometer for Mars and the NASA contextual camera.) Credit: NASA / JPL-Caltech / MSSS / JHU-APL
In 2020, NASA's next rover will depart from Cape Canaveral Air Force Base in Florida and head for the Jezero crater on Mars. Jezero once housed an ancient system of lakes and deltas that, according to scientists, would have captured and preserved information on the evolution of the red planet and, if so, on traces of ancient life.
Thomas Zurbuchen, badociate director of the NASA Science Mission Director, announced last week his choice among 60 candidates selected for their rich geology dating from 3.6 to 3.9 billion years. The decision has been made for many years and, before the site was finally chosen, scientists from around the world gathered in Glendale, California, to bring their expertise to the last four candidate landing sites during the last of the four workshops at the March 2020 landing sites.
Tanja Bosak, badociate professor in the Department of Earth Sciences, Atmosphere and Planets of MIT, was one of those scientists. His work uses experimental geobiology to explore modern biogeochemical and sedimentological processes in microbial systems. For Bosak, the Jezero Crater is the ideal landing site to learn about the potential livability of early March.
"The geology of the crater Jezero is very obvious [from orbit]"It is clear that the environment was livable in the past," says Bosak. "It is older than any sedimentary environment preserved in the Earth's rock archives.The Jezero crater preserves some of the most ideal types of rocks we use to search for life on Earth."
Clays and carbonates are minerals known to facilitate the preservation of fossils on Earth. Bosak's work as an investigator in the Simons Collaboration on the Origins of Life (SCOL) contributed to a lecture at the October workshop titled "In Search of Prebiotic Signatures with the March 2020 robot ", given by David Catling. Catling is a professor of Earth Sciences and Space at the University of Washington and is also a researcher at SCOL.
In his speech, Catling explained that even though life had never emerged on Mars, scientists might wonder if prebiotic precursors were still present in the Martian environment – essential information for determining the conditions necessary to life.
Roger Summons, Schlumberger Professor of Geobiology at EAPS and SCOL researcher, also contributed to the presentation. As principal investigator of the Complex Life Foundations team at the NASA Astrotics Institute MIT and a member of the research team of the NASA astrophysics institute. Samples on Mars using NASA's Curiosity robot, Summons' work focuses on preserving organic matter from different environments on Earth and Mars.
"Through our efforts to trace back the oldest life on Earth, we know that the best chance of finding convincing and credible evidence will come from studies of well-preserved, fine-grained layered rocks deposited under mbades of stagnant water ", Invocation said.
Earlier in the year, Bosak and Summons both contributed to "A Field Guide to Fossil Research on Mars," a review article published in the Journal of Geophysical Research this summarizes the strategies behind the search for old biosignatures among the different potentially habitable Martian environments. The authors of the review mentioned the favorability of sedimentary environments very similar to those of the Jezero crater, because badogues of these environments on Earth, such as deltas and lakes, have the greatest potential for collecting and preserving molecular fossils and body microbes.
In fact, organic matter has recently been detected in mudstones dating back 3 billion years ago at the site of an ancient lake at Gale Crater, the Mars Curiosity rover search site. The results, published in Science, has sparked increased interest in the potential preservation of organic matter at other landing sites on Mars, including the Jezero Crater. Indeed, unlike previous missions on Mars, Mars 2020 mission will not only measure in the Martian environment, it will also collect and cache sediment cores from sites of interest that will then be returned on Earth during a subsequent mission.
"Although the use of imaging and spectroscopy tools that can be used remotely on spacecraft can bring a lot to the learning, nothing compares to the sensitivity and the specificity of chemical instrumentation that we can access in laboratories all over the world, "says Summons. "This has been demonstrated time and time again by what has been learned in almost fifty years of studies on rocks that were made on Earth during the exploration of the moon by Apollo. . "
Bosak is particularly excited about the images and data that the rover will collect during his mission to the Jezero crater. The mission could determine if the carbonates on the edge of the crater are "precipitated out of the lake, as do the limestones". On Earth, "Early Earth limestones can have forms that record microbial interactions with sediments and mineral precipitation stimulated by microbes," said Bosak.
Ben Weiss, professor of planetary sciences at EAPS, also attended the workshop at the March 2020 landing site and introduced his co-author, Anna Mittelholz, a postgraduate student at University of British Columbia, on potential studies of the Mars magnetic field.
"Jezero will also be an extremely exciting place to get samples for understanding the history of the ancient Martian magnetic field," said Weiss. In the summer, Mittelholz and Weiss published an article in the journal Earth and Space Science titled "Candidate Landing Sites for March 2020: Magnetic Field Perspective", which details the results presented at the workshop.
During the course of the Mars planetary evolution, Mars lost its global magnetic field and much of its primitive atmosphere, which could have radically changed the Martian environment. Planetary magnetic fields are generated by the movement of metal fluids in planetary interiors during a process called dynamo. For example, the magnetic field of the Earth is generated and maintained from its molten core and rich in iron.
"The most important problem is to determine when the [Martian] dynamo off. This would help determine if the transition of the dynamo at the beginning made the transition from a hot and humid climate in early March to the current cold and dry state was brought about, "said Weiss. Jezero is a great place to test this hypothesis as it contains rocks and minerals with ages spanning the time we suspect the dynamo is extinguishing. "
Overall, mobile exploration and sample collection at the Jezero crater could help refine scientific knowledge in all disciplines.
"The Jezero crater will be a great place to understand the contribution of the dynamo to protecting the early atmosphere and livability of early March," Weiss said.
This information could also help us understand how and why life has settled on our own planet.
"I think it's as good as possible," says Bosak.
Explore further:
NASA chooses the old delta of the Martian River for the touch of the rover to 2020
More information:
Anna Mittelholz et al. Candidate Landing Sites of March 2020: Magnetic Field Perspective, Earth Sciences and Space (2018). DOI: 10.1029 / 2018EA000420
S. McMahon et al. A field guide to find fossils on Mars, Journal of Geophysical Research: Planets (2018). DOI: 10.1029 / 2017JE005478
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