NASA’s Perseverance Rover explores the geologically rich terrain of Mars
The latest discoveries provide more details about an area of the Red Planet that has a watery past and yield promising samples for the NASA-ESA Mars Sample Return campaign. NASA’s Perseverance Rover, well into its second science expedition, is collecting rock core samples from features in an area scientists have long considered a prime prospect for finding signs of ancient microbial life on Mars. Since July 7, the rover has collected four samples from an ancient river delta in the Red Planet’s Jezero crater, bringing the total number of scientifically exciting rock samples to 12. “We chose Jezero Crater for Perseverance to explore because we thought it had the best chance of providing scientifically excellent samples – and now we know we sent the rover to the right location,” said Thomas Zurbuchen, NASA’s associate science officer in Washington. “These first two science missions have yielded an amazing variety of samples that will be brought back to Earth by the Mars Sample Return campaign.” Jezero Crater, which is 28 miles (45 kilometers) wide, is home to a delta—an ancient fan-shaped feature that formed about 3.5 billion years ago at the convergence of a Martian river and lake. Perseverance is currently examining the delta’s sedimentary rocks, which formed when particles of various sizes settled into the once-aquatic environment. During its first science expedition, the rover explored the crater floor, locating igneous rocks, which form deep underground from magma or during volcanic activity on the surface. Perseverance Explores Jezero Crater Delta: NASA’s Perseverance Mars Rover has reached an ancient delta in Jezero Crater, one of the best places on the Red Planet to look for possible signs of ancient life. A delta is an area where scientists hypothesize that a river once flowed billions of years ago into a lake and deposited sediments in a fan shape. Credit: NASA/JPL-Caltech/ASU/MSSS “The delta, with its varied sedimentary rocks, contrasts beautifully with the igneous rocks — formed by magma crystallization — discovered on the crater floor,” said Perseverance project scientist Ken Farley of Caltech in Pasadena, California. “This juxtaposition provides us with a rich understanding of the geological history after the formation of the crater and a variety of samples. For example, we found a sandstone bearing grains and rock fragments created far from the Jezero crater – and a mudstone that includes interesting organic compounds.” A remarkable rock about 3 feet (1 meter) wide was given the name “Ridge Wildcat”. It probably formed billions of years ago as mud and fine sand settled into an evaporating saltwater lake. On July 20, the rover skimmed part of the surface of Wildcat Ridge. This allowed him to analyze the area with a sophisticated scientific instrument called Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals, or SHERLOC. According to the SHERLOC analysis, the samples include a class of organic molecules spatially correlated with those of the sulfate minerals. Sulfite minerals found in layers of sedimentary rock can provide important details about the aquatic environment in which they formed. Two Perseverance Sampling Sites in Jezero Delta: NASA’s Perseverance rover collected rock samples for possible future return to Earth from two sites seen in this image of Mars’ Jezero Crater: “Wildcat Ridge” (lower left) and “Skinner Ridge” (top right). Credits: NASA/JPL-Caltech/ASU/MSSS
What is organic matter?
Organic molecules are made up of a wide variety of compounds consisting mainly of carbon and usually also including hydrogen and oxygen atoms. In addition, they may contain other elements such as nitrogen, phosphorus and sulphur. Although there are chemical processes that produce these molecules that do not require life, some of these compounds are the chemical building blocks of life. The presence of these particular molecules is considered a potential biosignature – a substance or structure that could be evidence of past life but may also have been produced without the presence of life. In 2013, NASA’s Curiosity Mars rover found evidence of organic matter in rock dust samples, and Perseverance has previously detected organics in Jezero Crater. But unlike that earlier discovery, this latest detection was made in an area where, in the distant past, sediments and salts had been deposited in a lake under conditions in which life could have existed. In the analysis of Wildcat Ridge, the SHERLOC instrument recorded the most abundant organic detections on the mission so far. “In the distant past, the sands, silts and salts that now make up the Wildcat Ridge sample were deposited under conditions where life could potentially have thrived,” Farley said. “The fact that organic matter was found in such sedimentary rock – known for preserving fossils of ancient life here on Earth – is significant. However, as capable as our instruments on Perseverance are, further conclusions about what is contained in the Wildcat Ridge sample will have to wait until it returns to Earth for in-depth study as part of the agency’s Mars Sample Return campaign.” Sample collection and rock analysis at ‘Wildcat Ridge’: Consisting of multiple images from NASA’s Perseverance Mars rover, this mosaic shows a rocky outcrop called ‘Wildcat Ridge’, where the rover extracted two rock cores and ground a circular piece for to investigate the composition of the rock. Credits: NASA/JPL-Caltech/ASU/MSSS The first step in the NASA-ESA (European Space Agency) Mars Sample Return campaign began when Perseverance cored the first rock sample in September 2021. Along with the rock core samples, the rover has collected an atmospheric sample and two control tubes. All of this is stored in the rover’s belly. The geological diversity of the samples already brought to the rover is so good that the rover team is considering depositing selected pipes near the base of the delta in about two months. After depositing the cache, the rover will continue its delta explorations. “I have studied the habitability and geology of Mars for much of my career and know firsthand the incredible scientific value of returning a carefully curated collection of Martian rocks to Earth,” said Laurie Leshin, director of NASA’s Jet Propulsion Laboratory. . “That we are weeks away from developing Perseverance’s fascinating specimens and just years away from bringing them to Earth so scientists can study them in exquisite detail is truly amazing. We will learn so much.”
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Astrobiology is a key goal for the Perseverance mission to Mars, including storing samples that may contain signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, help pave the way for human exploration of the Red Planet, and be the first mission to collect and store Martian rocks and regolith. Subsequent NASA missions, in collaboration with ESA, will send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis. The Mars 2020 Perseverance mission is part of NASA’s exploration approach from the Moon to Mars. This includes crewed Artemis missions to the Moon to help prepare for human exploration of the Red Planet. JPL, managed by Caltech for NASA, built and operates the Perseverance rover.
