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NASA wisely chose the landing site for its Perseverance Mars rover, a life hunter.
Perseverance landed in February on the floor of the 45-kilometer-wide Jezero Crater, which was chosen primarily because previous observations from Mars orbiters suggested it was home to a large lake and river delta in the ancient past.
Photos taken by Perseverance at the start of its mission, even before the car-sized robot begins to move, confirm this interpretation, reports a new study.
“Without driving anywhere, the rover was able to solve one of the big unknowns, which was that this crater was once a lake,” said Benjamin Weiss, co-author of the study, professor of planetary science at the Massachusetts Institute of Technology. declaration. “Until we landed there and confirmed it was a lake, it was still a question.”
Related: Where to find the latest Mars photos from NASA’s Perseverance rover
A good site for a daring mission
Perseverance has two main tasks during its $ 2.7 billion mission: to search for signs of past life on Mars, and to collect and cache dozens of samples for future return to Earth. (The rover also supported and documented the early sorties of its travel companion, NASA’s Ingenuity Mars helicopter, which now flies more independently on the Red Planet.)
Jezero Crater was considered a good place to do this job, based on data collected by spacecraft such as NASA’s Mars Reconnaissance Orbiter. Orbital imagery showed a fan-shaped feature in Jezero that mission team members interpreted as a delta – a place where a river flowed into a lake about 3.7 ago billions of years ago, depositing sediment that could harbor evidence of ancient Martian microbes, if any.
In the new study, which was published online today (October 7) in the journal Science, researchers analyzed the first photos Perseverance took from a distance of this putative delta with its Mastcam-Z imaging suite and a camera on his SuperCam instrument. .
These photos captured the edge of the large delta outcrop as well as an isolated mound dubbed “Kodiak,” which the team believe is an eroding remnant of the same formation. The Kodiak imagery was particularly sharp, and the team saw distinct layers of sediment in it that could only have been deposited by a river flowing into a lake.
Kodiak’s observations “unambiguously indicate a river deposit [sediments] with a delta and a lake, ”study co-lead author Nicolas Mangold from the French National Center for Scientific Research and the University of Nantes told Space.com by email. (The other co-lead author is Sanjeev Gupta of Imperial College London.)
“This helps us to limit the level of the lake and will help us build a scenario of delta formation and lake activity along the Perseverance crossing, and also identify the right layers to analyze and sample” said Mangold.
Interestingly, observations from Perseverance show that ancient Lake Jezero was about 330 feet (100 meters) lower than orbital data had suggested, “marking a phase of the delta long after it began to form.” said Mangold.
“We cannot extrapolate at the start of Jezero’s evolution, before the material was deposited at Kodiak, as the corresponding layers are hidden further down the delta,” he added. “But Perseverance may be able to produce more results on this when it crosses the delta.”
Water on Mars: exploration and evidence
A changing Jezero
Jezero is dry today, like the rest of the Martian surface. Scientists believe the Red Planet dried up around 3.5 billion years ago, after its global magnetic field died away and its once thick atmosphere became susceptible to being stripped by charged particles from the sun. .
The newly analyzed photos can provide intriguing insight into this big change. For example, imagery from Perseverance also shows large boulders, some up to 5 feet (1.5 m) wide, in the upper (younger) layers of the main outcrop of the Jezero Delta. It took a powerful flow to transport such large rocks – likely a flood that displaced up to 106,000 cubic feet (3,000 cubic meters) of water per second, study team members said.
Such fluxes may have resulted from “glacial surges” or precipitation-induced flash floods like those occurring today in some desert regions of Earth, Mangold said. Whatever the cause, the rock deposits could indicate a very different Jezero than the one that produced the earlier lake sediments.
“The most surprising thing that emerges from these images is the potential opportunity to capture the moment this crater has gone from an Earth-like habitable environment to this desolate landscape that we now see,” Weiss said in the same. communicated. “These rock beds may be records of this transition, and we haven’t seen this in other places on Mars.”
Perseverance will eventually see the formation of the delta up close, if all goes according to plan. The team aims to drive the rover, which has traveled 1.62 miles (2.61 km) over Jezero soil to date, to the delta outcrop and collect samples deposited during the calm lake era. (Perseverance has already collected two of several dozen planned samples, which will be transported to Earth by a joint NASA-European Space Agency campaign, possibly as early as 2031.)
But Perseverance, and NASA’s other Martian robots, are temporarily halted because the red planet is currently on the other side of the sun from Earth. Our star may corrupt Mars-related commands in the current planetary setup, so NASA has imposed a two-week communications blackout that ends on October 16.
Mike Wall is the author of “The low“(Grand Central Publishing, 2018; illustrated by Karl Tate), a book about finding alien life. Follow him on Twitter @michaeldwall. Follow us on twitter @Spacedotcom or Facebook.
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