NASA’s Perseverance rover begins key search for life on Mars

Perseverance arrived at the base of an ancient river delta on Mars in April.Credit: NASA/JPL-Caltech

More than fifteen months after landing in Jezero Crater on Mars, NASA’s Perseverance rover has finally begun its hunt for ancient life in earnest.

On May 28, Perseverance crushed a circular slab 5 centimeters wide into rock at the base of what was once a river delta in the crater. This delta was formed billions of years ago when a long-extinct river deposited layers of sediment in Jezero, and it’s the main reason NASA sent the rover here. On Earth, river sediments are usually teeming with life.

Images of the freshly crushed stain show small grains of sediment, which scientists hope will contain chemical or other traces of life. “To see a world in a grain of sand” by poet William Blake comes to mind,” wrote Sanjeev Gupta, a planetary geologist at Imperial College London. on Twitter.

Close-up view of a sampling site photographed by NASA's Mars Perseverance rover.

The rover crashed into its first rock in the river delta in late May, clearing a circular area for inspection.Credit: NASA/JPL-Caltech/ASU

The rover will spend the next few months exploring the Jezero Delta, while mission scientists decide where they want to drill and extract rock samples. NASA and the European Space Agency (ESA) plan to retrieve these samples and return them to Earth for study no earlier than 2033, in the first-ever sample return from Mars.

“Go to the buffet”

Perseverance landed in February 2021, several kilometers from the edge of the delta. He spent most of his first few months exploring the floor of the crater – which is unexpectedly made of igneous rock, a type that forms when molten material cools. It was a science jackpot because scientists can date igneous rocks based on the radioactive decay of their chemical elements. But many researchers have been keen for Perseverance to go to the delta, whose fine-grained sediments have the best chance of harboring evidence of Martian life.

The rover finally arrived at the delta base in April. He quickly spotted thin-layered gray rocks called mudstones, which could have formed from sediments deposited by a slow-moving river or lake. He also found coarse-grained sandstone, which could have formed in a fast-flowing river. These types of rocks are excellent targets for studying a variety of Martian environments where life could have thrived, said Katie Stack Morgan, associate scientist for the Perseverance Project at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. May during the online portion of the 2022 Astrobiology Scientific Conference.

A color-enhanced image of the Jezero Crater Delta, which once housed a lake.

A delta formed in Jezero Crater billions of years ago, when an ancient river (whose bed is shown at left) flowed through the formation and deposited sediment (center of l ‘image). Sediments tend to contain organic matter, making them a good place to look for signs of ancient life.Credit: NASA/JPL/JHUAPL/MSSS/Brown University

Mission engineers then chased Perseverance out of this area, named Enchanted Lake, and to another area known as Hawksbill Gap, where he is currently working. The freshly abraded patch was made into a sandstone in one of the lowest rock layers in the delta, which means it is one of the oldest rocks formed by the ancient Jezero River and therefore an excellent place to look for signs of ancient life.

The delta rises about 40 meters above the crater floor. Rover drivers plan to send Perseverance to the front of the delta and then back down, assessing where and how to take samples. “It’s like going to the buffet before filling your plate,” says Jennifer Trosper, mission project manager at JPL. As it ascends, it will explore the rocks, including abrading more patches to see inside the rocks. As it descends, it will drill and collect some of the most intriguing samples.

Like a child assembling a set of gemstones for its treasured collection, mission scientists deliberate which rocks the rover should sample to amass the most geologically diverse cache. Perseverance carries 43 sample tubes, each slightly thicker than a pencil. NASA and ESA plan to bring around 30 filled tubes back to Earth.

Mission scientists are already considering where to deposit the first set of samples that a future spacecraft can pick up. Once the rover descends, it could place tubes at the base of the delta, in a large flat area between Enchanted Lake and Hawksbill Gap. “There is a very strong possibility that we will set up the first cache” when the rover arrives there, says Kenneth Farley, mission project scientist and geochemist at the California Institute of Technology in Pasadena. “This is where it gets real.”

Mission planners didn’t expect to drop samples so soon, but the location is excellent – flat and with few rocks that could get in the way of a future sample-returning spacecraft. “It’s just a great place to land on Mars,” Trosper says.

NASA plans to hold a community meeting for planetary scientists in September to assess whether the collection it has so far is “scientifically worthy” enough to recover. This is a key issue due to all the time and money it takes to return tubes. NASA wants the wider community to assess the mission team’s view that “we have assembled the highest value cache that we believe this site has available to us,” Farley says.

A productive mission

NASA and ESA are working on a $5 billion plan to send two landers to Mars — carrying a rover that would collect the samples and a rocket that would send them to Mars orbit — as well as a spacecraft that would retrieve them from Mars. orbit and bring them back to Earth. The first launches were supposed to take place in 2026, but this schedule was changed by Russia’s invasion of Ukraine. ESA interrupted all cooperation with the Russian space agency during the war. Tensions have derailed a planned Russian-European Mars rover – and now NASA and ESA are redrawing their Mars landing plans. They have time: Perseverance’s sample tubes are designed to last for decades in Martian conditions.

In addition to collecting rock samples, Perseverance made other discoveries at Jezero, including how dust devils kick up large amounts of dust into the air.1 and how the speed of sound fluctuates in Mars’ carbon dioxide-rich atmosphere2. The rover has so far covered more than 11 kilometers, and it set an extraterrestrial distance record by covering 5 kilometers in 30 Martian days, in March and April.

Perseverance’s sidekick, the small helicopter Ingenuity, has been instrumental in some of the rover’s accomplishments, but its time on Mars may be coming to an end. Originally designed to perform just 5 flights, it defied expectations by performing 28. From its vantage point in the sky, it helped spot the best routes for Perseverance, and it surveyed the flat area at the delta base where future missions could land.

Animated footage acquired by NASA's Ingenuity Mars helicopter during its 25th flight.

The rover’s companion helicopter, Ingenuity, captured the footage during its 25th flight on April 8. It was his longest and fastest flight to date (although this GIF was sped up by a factor of five, for visibility).Credit: NASA/JPL-Caltech

In early May, however, Ingenuity lost communication with the rover when dust in the atmosphere blocked sunlight, which the helicopter needs to charge its solar panels and battery. Ingenuity now faces dusty skies and colder temperatures as the Martian winter descends, and may eventually struggle to fly.

“No matter what happens,” says Farley, “the ingenuity has succeeded.”

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