Mars rover collects rocks for first time
Second collection attempt yields soil indicative of water once existing on planet
This time, the rock did not disappear.
After a perplexing failure last month, NASA’s latest Mars rover, Perseverance, was able to drill 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. Then Perseverance will seal the collection tube and put it away in its belly.
The success, visible in images posted online Thursday, is most likely a relief to scientists working on the mission.
“You can see a beautiful rock core,” Kenneth A. Farley, a professor of geochemistry at the California Institute of Technology and the project scientist for Perseverance, said in an email on Thursday morning.
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.
And yet, on 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,” Farley 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,” Jennifer Trosper, the mission’s project manager, 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. She added that despite numerous tests on Earth, “we had not encountered a rock in our test suite that behaved in quite this manner.”
Farley concedes that there were warning signs that the August rock might not have been the best one to try first. Its brown color indicated rust, it contained salts, and it was full of holes.
Rust, salts and holes meant the rock 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.
But a rusty, salty rock filled with holes could also be very crumbly. “We learned a lesson,” Farley said.
The operation was not a complete loss. The tube has no rock or soil, but it does contain sealed, uncontaminated Martian air, something the scientists had planned to collect at another time.