Perseverance reached the base of an ancient river delta on Mars in April. Credit: NASA / JPL-Caltech
More than fifteen months after landing on Jezero Crater on Mars, NASA’s Perseverance rover has finally begun the search for real life.
On May 28, Perseverance landed a 5-centimeter-wide circular piece on a rock at the base of what was once a river delta in the crater. This delta formed billions of years ago, when a long-lost river deposited layers of sediment in Jezero, and this is the main reason why NASA sent the rover here. On Earth, river sediments are usually full of life.
Images of the freshly ground stain show small grains of sediment, which scientists expect to contain chemical or other traces of life. “Seeing a World in a Grain of Sand” by poet William Blake wrote on Twitter Sanjeev Gupta, a planetary geologist at Imperial College London.
The rover fell to its first rock in the river delta in late May, clearing a circular patch 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, on the first return of samples from Mars.
“Go to the buffet”
Perseverance landed in February 2021, several miles from the edge of the delta. He spent many of his early months exploring the crater floor, which is unexpectedly made of igneous rocks, a type that forms as molten materials cool. It was a scientific award because scientists can date igneous rocks based on the radioactive decay of their chemical elements. But many researchers have wanted Perseverance to reach the delta, whose fine-grained sediments have the best chance of hosting evidence of Martian life.
The rover finally reached the base of the delta in April. He soon detected gray, thin-layered rocks called mud, which could have formed from sediment deposited by a slow river or lake. He also found sandstones with large thicknesses, which could have formed in a fast-flowing river. These rocks are great targets for studying a variety of Martian environments where life could have thrived, said Katie Stack Morgan, an assistant scientist for the Perseverance Project at the Jet Propulsion Laboratory (JPL) in Pasadena, California. May during the online part of the 2022 Astrobiology Science Conference.
A delta formed in the Jezero crater billions of years ago, when an ancient river (whose bed is shown on the left) emptied into the formation and deposited sediment (center of the image). Sediments tend to contain organic matter, making it a good place to look for signs of ancient life. Credit: NASA / JPL / JHUAPL / MSSS / Brown University
Mission engineers moved Perseverance away from this region, called Enchanted Lake, and to another area known as Hawksbill Gap, where he currently works. The freshly burned patch was made of sandstone in one of the lowest rock layers in the delta, meaning it is one of the oldest rocks formed by the ancient Jezero River and therefore an excellent place to hunt for signs of ancient life.
The delta rises about 40 meters above the crater floor. Rover drivers plan to send Perseverance across 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 the plate,” says Jennifer Trosper, project director for the mission at JPL. On the way up, you’ll explore the rocks, including scraping more patches to see the insides of the rocks. On the way down, he will drill and collect the most intriguing samples.
As a child assembling a set of gemstones for his prized collection, mission scientists are deliberating on which rocks the rover should test to accumulate the most geologically diverse cache. Perseverance carries 43 tubes for samples, each a little thicker than a pencil. NASA and ESA plan to return about 30 full tubes to Earth.
Mission scientists are already considering where to put the first set of samples for a future spacecraft to retrieve it. Once the rover comes down again, it could put some tubes at the base of the delta, in a large flat region between Enchanted Lake and Hawksbill Gap. “There’s a good chance we can drop the first cache” when the rover arrives, says Kenneth Farley, a mission project scientist and geochemist at the California Institute of Technology in Pasadena. “That’s when it becomes real.”
Mission planners did not expect to sample so soon, but the location is excellent: flat and with few rocks that could interfere with a future sample return spacecraft. “It’s a great place to land on Mars,” says Trosper.
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 be collected. This is a key question because of all the time and money required to return the tubes. NASA wants the wider community to evaluate the mission team’s view that “we’ve gathered the most valuable cache we believe this site has at our disposal,” says Farley.
A productive mission
NASA and ESA are working on a $ 5 billion plan to send two ground launchers to Mars, with a rover picking up the samples and a rocket sending them into Mars orbit, as well as a spacecraft trauria. orbit them and make them fly back to Earth. The first launches are expected to take place in 2026, but this timeline was changed by the invasion of Ukraine by Russia. ESA stopped all cooperation with the Russian space agency because of the war. Tensions have derailed a planned Russian-European rover from Mars, and now NASA and ESA are redrawing their plans to land on Mars. They have time: Perseverance sampling tubes are designed to last for decades in Martian conditions.
In addition to taking rock samples, Perseverance has made other discoveries in Jezero, such as how dust devils drag large amounts of dust into the air1 and how the speed of sound fluctuates in the carbon-rich atmosphere of Mars2 . The rover has so far covered more than 11 kilometers and set an extraterrestrial distance record when it covered 5 kilometers in 30 Martian days, in March and April.
Perseverance’s companion, the small Ingenuity helicopter, has been instrumental in some of the rover’s achievements, but his time on Mars may be coming to an end. Originally designed for only 5 flights, it defied expectations by completing 28. From its vantage point in the sky, it has helped find the best routes for Perseverance and studied the flat area of the delta base where future missions they could land.
The rover’s auxiliary helicopter, Ingenuity, filmed these images during its 25th flight on April 8. It was his longest and fastest flight to date (although this GIF has been accelerated by a factor of five, for visibility). Credit: NASA / JPL-Caltech
In early May, however, Ingenuity lost communication with the rover when dust from the atmosphere blocked sunlight, which the helicopter needs to charge its solar panels and battery. The craft now faces dusty skies and colder temperatures as the Martian winter descends, and it could eventually have trouble flying.
“Whatever happens,” says Farley, “the ingenuity has been successful.”