NASA NASA’s Perseverance Mars rover has dug up new rock samples at the bottom of a Martian river as part of its search for evidence of past life. Perseverance is in the midst of its second Martian rock collection campaign and has now collected four more samples of sedimentary rock from a river delta that once flowed into Jezero Crater, bringing its collection to a total of 12 samples since it launched on July 7.
NASA chose the river delta because it offered the highest chance of finding signs of ancient microbial life. From antiquity – if NASA ever finds evidence – that microbial life would have existed about 3.5 billion years ago, when the river bed was formed. Persistence removes sedimentary rock from a section where the Martian River and a lake meet in Jezero Crater. The crater itself is 28 miles (45 km) wide. Thomas Zurbuchen, NASA’s deputy administrator for science in Washington, said Perseverance had collected an “amazing variety” of samples that will be shot back to Earth in the Mars Sample Return campaign over the next decade. “We chose the 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,” Zurbuchen said in a press release. For the return campaign, NASA plans to launch the Sample Retrieval Lander to Mars in 2028 and land in Jezero Crater. The aircraft will carry a NASA-led Mars rocket and a pair of small Mars helicopters. Only when the samples are returned to Earth will the NASA scientist know for sure what they are made of. But if SpaceX chief Elon Musk is right, humans could be on Mars before the rock samples return to Earth. Musk’s latest bet is that the earliest date for humans to land on Mars is 2029.
Perseverance and its sister Ingenuity landed on Mars on February 18, 2021, about seven months after launching from Cape Canaveral, Florida. Perseverance’s first expedition explored the floor of Jezero and collected igneous rocks, which contain crystals that can tell exactly when they were formed. Instead of sedimentary rocks being collected now, igneous rocks are formed in molten lava or during volcanic activity. The rover has a SuperCam equipped with a rock evaporation laser, which hit the rocks during the first expedition to determine that it was igneous rock covering the crater floor. The two different rock types give NASA the ability to understand the crater’s geological past. “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 .” The new evidence found for organic molecules on Mars is more promising than the Curiosity rover’s 2013 finding of organic matter, according to NASA. What makes Perseverance’s discoveries interesting is that the organic molecules it found are in an “area where, in the distant past, sediments and salts were deposited in a lake under conditions in which life could possibly have existed.” These were found in a section of the crater called Wildcat Ridge. “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 a sedimentary rock—known for preserving fossils of ancient life here on Earth—is significant. However, as capable as our instruments at Perseverance are, further inferences about what is contained in 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.”