Written by: Alexandra Fitz
More than 15 months after landing at Jezero crater on Mars, NASA’s Perseverance rover has begun its relentless search for signs of past life on the planet.
On the 28th of last May, the rover blew up a boulder to obtain a circular sample, 5 centimeters in diameter, from the rocks located in the delta of a river in the crater, or as it was in the past. This delta was formed billions of years ago, when an ancient river dumped its sediments to form layers in that crater, and primarily for it, “NASA” sent the rover there; Because the sediments of the rivers of the planet are usually teeming with life.
The images of the rover sample show tiny grains of sediment that scientists hope may contain chemical or other traces of life on the Red Planet. In a tweet, Sanjeev Gupta, a planetary geologist at Imperial College London, wrote that the images recalled a line from a poem by William Blake, which he translated: “Seeing a world in a grain of sand.”
The rover will spend the next few months exploring the Jezero delta, while scientists decide where to dig for samples of Martian rock. NASA and the European Space Agency intend to capture these samples and return them to Earth by 2033 at the earliest, to be the first samples brought from Mars to Earth.
The Perseverance rover landed on Mars in February 2021, several kilometers from the edge of the delta. She spent much of her first months on Mars exploring the bottom of the crater, which turned out, unexpectedly, to be made of igneous rocks; They are rocks that form when molten materials cool. Thus, scientists are lucky, as they will be able to determine the age of igneous rocks based on the radioactive decay of the chemical elements in them. But many researchers were eager for the rover to reach the delta, believing that its sediments, with their fine grains, could hold the most significant evidence of life on Mars.
The rover finally reached the base of the delta last April, finding thin, gray rocks that scientists called “mudstones”, which may have formed from sediments that formed on the banks of a slow-flowing river or lake. I also found coarse-grained sandstones, which may have been formed by a fast-flowing river.
These stones are an ideal target for studying a wide range of Martian environments in which life may have arisen, said Kitty Stack-Morgan, the mission’s undersecretary for scientific affairs at the Jet Propulsion Laboratory (JPL) in Pasadena, California, on May 17th. , in the online segment of the 2022 Astrobiology Conference.
Next, mission engineers directed the craft out of the so-called Enchanted Lake toward the so-called Hawksbill Gap, where the craft is currently operating. The sample was burrowed out of sandstone in one of the lowest layers of delta rocks; Evidence that this rock is one of the oldest rocks formed by the extinct Jezero River, and therefore it is an ideal place to search for traces of previous life.
Exploration tour before sampling
The delta rises about 40 meters above the crater bottom. They will ride the craft to the front of the delta and back, and in the meantime, they will study where and how they should dig for samples. “It’s like taking an overview of the dining table, exploring what’s on it, before you start filling your plate,” says Jennifer Trosper, mission project manager at the lab. The spacecraft will examine the rocks on its way up, and in the meantime, it will work through more samples so that scientists can see the interior of the rocks. On the way back, the craft will dig into the rocks that the scientists found intriguing, in order to collect samples of them.
Like a child collecting precious stones to add to his favorite collection, scientists debate among themselves which rocks they should sample, so that their sample collection is as diverse as possible geologically. The craft is carrying 43 sample tubes, each a bit thicker than a pencil. NASA and the European Space Agency plan to bring to Earth 30 of these tubes after filling them.
In fact, scientists are now researching which locations the first batch of samples could be left in, for future spacecraft to bring. Once the craft completes its return journey, it may deposit some samples at the base of the delta, in a wide flat land between the “Enchanted Lake” and the “hawk’s beak gap”. “It’s very possible that the rover will create its first cache of samples there,” says Kenneth Farley, the project’s scientific supervisor and a geochemist at the California Institute of Technology in Pasadena.
Mission supervisors weren’t expecting to start getting samples and depositing them so quickly, but the spacecraft is ideal for future spacecraft, as Trosper describes it: “It’s a really excellent location for landing on Mars.”
NASA intends to hold a public meeting of planetary scientists next September; To assess the samples it collected, and whether their scientific value makes them worthy of another expedition to bring them to Earth.
This is a central question, given the time and money it takes to return samples. NASA wants to involve a broader spectrum of the scientific community in order to evaluate the samples and see if they are, as the mission team sees them, “the most valuable set of samples we think we can get from this site,” Farley says.
The mission pays off
NASA and the European Space Agency are working on a $5 billion plan to send two landers to Mars, carrying a sample rover and a rocket that will launch into Mars orbit, as well as a Mars orbiter sampler and back to Earth. The first missions were scheduled for 2026, but that schedule changed due to the Russian invasion of Ukraine; The European Space Agency suspended all of its joint activities with the Russian Space Agency due to the war. Existing tensions have also hampered plans for a joint Russian-European project to send a rover to Mars. Now, NASA and the European Space Agency are working on new plans for their future missions on Mars. The two agencies have plenty of time; The sample tubes carried on board Perseverance are designed to withstand the harsh conditions of Mars for decades.
In addition to taking samples of Martian rocks, Perseverance has made other discoveries in Jezero crater, including learning how cyclones throw large amounts of dust into the air (CE Newman et al. Sci. Adv. 8, eabn378; 2022), and how the speed of sound oscillates in the carbon dioxide-rich climate of Mars (S. Maurice et al. Nature 605, 653–658; 2022).
The spacecraft Perseverance has so far traveled more than 11 kilometers and set a new extra-terrestrial distance record, when it traveled 5 kilometers in 30 sols, in March and April.
The small helicopter Ingenuity, Perseverance’s companion on its mission, was pivotal in some of the rover’s accomplishments, but its life on Mars appears to be coming to an end. The helicopter was originally designed to perform only 5 flights, but it exceeded all expectations, performing 28 flights. From an overhead perspective, it helped determine the best paths for Perseverance, and a flat area at the base of the delta, which might be a suitable landing pad for new missions in the future.
But in early May, the Ingenuity lost contact with the Perseverance spacecraft, when dust in the atmosphere blocked the sunlight the helicopter needs to charge its solar cells and battery. The helicopter is now suffering from dusty skies and low temperatures, coinciding with the Martian winter, and may eventually be unable to fly.