On Mars, NASA’s rover drilled into rocks it came for

After a perplexing failure last month, NASA’s latest Mars rover, Perseverance, was able to successfully collect a sample of rock on Wednesday. The rover took pictures of the rock in the tube and sent the images to Earth so that mission managers could be sure they had not come up empty again. The rock was there. Adam Steltzner, the chief engineer for the rover, enthused on Twitter on Thursday morning, describing it as “one beautifully perfect cored sample.”

Holding the tube vertically, Perseverance shook the tube, held vertically with the opening on top, Five shakes lasting one second each were to help the rock core settle farther down into the collection tube. In subsequent photographs, the core could no longer be seen. Had it disappeared? Was Mars messing with us? Late in the day on Thursday, NASA said in a news release that the mission team remained confident the rock was still in the collection tube, hidden in shadows. It would be surprising if the shaking could have caused the rock to jump up and out of the tube. But NASA said the rover would take more pictures when the lighting was better before sealing the tube and putting it away in its belly.

“We did what we came to do,” Jennifer Trosper, the project manager for the mission, said in the news release. “We will work through this small hiccup with the lighting conditions in the images and remain encouraged that there is sample in this tube.” One of the key tasks for Perseverance is to collect rocks and soil that will eventually be brought back to Earth by another mission so that scientists can exhaustively study them using state-of-the-art instruments in their laboratories, the way they have with moon rocks from the Apollo and Soviet missions of the 1960s and ’70s. What the scientists and engineers did not want was a repeat of Aug. 6, the first time that Perseverance drilled, collected and sealed a rock sample. Everything appeared to go flawlessly — except the tube was empty. “It was definitely a bit of despair,” Kenneth A. Farley, a professor of geochemistry at the California Institute of Technology and the mission’s project scientist, said in an interview before the latest drilling attempt. “Everybody was so ready to declare victory. And then somebody said, ‘Yeah, here’s a picture, there’s nothing in the tube.’ It was very deflating.”

The rover used its cameras to look around and see if the rock core had somehow dropped to the ground. But there was no sign of it. The rock sample had, it seemed, vanished. The greatest worry was that Perseverance’s intricate drilling mechanism had suffered a crippling malfunction and that it would not be able to collect any samples at all. But after reviewing the data, the engineers and scientists concluded it was the rock, not the rover, that was to blame. “The rock simply wasn’t our kind of rock,” Trosper wrote in a NASA blog post on Aug. 19. The rover’s systems had performed as expected — “quite well, as a matter of fact,” Trosper wrote — but the rock was too fragile. “The act of coring into it resulted in the rock breaking apart into powder and small fragments of material, which were not retained in the tube due to their size,” Trosper said.

Dr. Farley concedes that there were warning signs that the August rock might not have been the best one to try first. Its brown colour indicated rust, it contained salts, and it was full of holes. That meant it had been sitting in a lake or groundwater for a very long time. That was potentially a fantastic scientific find. The mineralogical changes caused by water could illuminate billions of years ago when Mars was wet and habitable.