Since July, NASA’s Perseverance rover has dug into sedimentary rock on Mars and brought back four thin cores. Scientists are ecstatic because at least two of the cores likely contain organic molecules, and they are the first of this sort of rock to be gathered on another Earth.
Organics, which are carbon-containing molecules, are commonly linked to life on Earth, but they can also be created independently of living beings. These rocks were gathered by the Perseverance rover from an old delta in Mars’s Jezero Crater, where a river once deposited layers of sediment and potentially other stuff. It’s not uncommon for river deltas to be teeming with life on Earth. If life ever existed in Jezero, NASA has the best chance of discovering it in these cores.
Tanja Bosak, a geobiologist at the Massachusetts Institute of Technology in Cambridge, believes that having access to the cores is “wonderful” if scientists are ever going to figure out the answer to that issue. NASA and the European Space Agency intend to send additional spacecraft to Jezero in the following years in order to retrieve the cores that Perseverance has collected and bring them back to Earth, where they will be analyzed by scientists using cutting-edge laboratory methods. This will be the first time ever that Martian soil has been returned to Earth, and it won’t happen until at least 2033.
The director of the Jet Propulsion Laboratory in Pasadena, California, Laurie Leshin, remarked at a press briefing on September 15 that “we need a great suite of rocks to bring back” in order to take on the difficulty and cost of a Mars sample-return mission. We’ve gotten off to a terrific start. The Perseverance landed in February of 2021 in Jezero Crater, which is 45 kilometers across. The 3.5 billion year old river delta, where sediments eventually transformed into rock, is its primary destination and primary purpose in the search for clues of ancient life.
It took Perseverance over a year to get to the delta, where it would conduct its primary research. Scientists had hoped to land closer to the delta, but instead it landed further away. As it drove about Jezero’s floor, it made an unexpected discovery: rocks called “igneous” that are produced when magma cools and hardens. Sedimentary rock was what researchers anticipated seeing at the bottom of the crater, which was formerly a lake. When the Perseverance reached the delta in April 2022, scientists finally located the object of their search. The rover has gathered two sets of cores from the sedimentary rocks that make up the delta’s margin over the past few months.
One pair is sourced from the Skinner Ridge outcrop, which is composed of fine-grained sandstone like that found in many locations on our planet. The Skinner Ridge cores, when examined closely in the sampling tubes of the Perseverance, appear to be a pale color and to be studded with rounded granules of black material. These darker grains most likely originated from locations hundreds of kilometers away and were brought by the old river that previously flowed into Jezero. Researching the grains could perhaps provide clues to the distant past of Mars.
The second set of newly retrieved cores comes from a location known as Wildcat Ridge, which is only around 20 meters away from Skinner Ridge. These swatches have a brighter hue and are more consistent in tone. Even finer-grained than the Skinner Ridge cores, they appear to be a mudstone. There is a higher probability that a rock with smaller grains ever contained life. Small grains on Earth have a habit of sinking to low-energy locations, like the bottom of a pond, where they can preserve decomposing creatures or other evidence of life that have settled there.
As previously mentioned, the organic compounds were discovered by scientists at Wildcat Ridge. The rover ground a 5-centimeter-wide circle into the rock adjacent to where Perseverance dug its two cores. This revealed the rock’s internal texture. The robotic arm of the rover was extended and used to analyze the composition of the rock’s minerals. Sunanda Sharma, a planetary scientist at the Jet Propulsion Laboratory, said it turned out to be richer in organics than any site analyzed by Perseverance so far. In addition, sulfate mineral abundance correlates with the presence of organics, suggesting that these areas may be favorable for the preservation of life. According to Sharma, this indicates that organics and sulfate minerals became concentrated during the evaporation of the lake that formerly filled Jezero.
The intrepid rover Perseverance has gone on to another previously visited region, this one known as Enchanted Lake. There, it will do its thing, bringing back two more samples of fine-grained rock and whatever else it can find on Mars’s surface. Before the year is up, it will likely deposit six or more core samples on the ground as a preliminary assemblage of rocks that could be recovered at a later date. The Perseverance will continue its exploration of Jezero with the remaining tubes, some of which will be empty. It will eventually rise above the delta and roll out of the crater onto the prehistoric landscape beyond. The little helicopter Ingenuity, which accompanied Perseverance, has lasted far longer than its creators anticipated. It’s already made 31 flights despite being built for just 5. The rover’s forward progress has been scouted in large part due to the pilot’s creative thinking.