The rock appeared exactly where it should have been – captured in the drill bit of NASA’s newest Mars rover, Perseverance.

After a baffling failure last month, NASA’s newest Mars rover, Perseverance, successfully collected a rock sample on Wednesday. The rover took pictures of the rock in the tube and sent the pictures back to Earth so the mission leaders could be sure they didn’t come up empty again. The stone was there.

Adam Steltzner, the rover’s chief engineer, raved on Twitter on Thursday morning and described it as “a beautifully perfect core sample”.

Holding the tube vertically, Persistence shook the tube, which was held vertically with the opening up. Five shakes of one second each should help the rock core to settle deeper into the collection tube.

The core could no longer be seen in the following photos. Was it gone? Did Mars play with us?

On Thursday evening, NASA announced in a press release that the mission team was still confident that the rock was still in the collecting tube, hidden in the shade. It would be surprising if the shaking had caused the rock to bounce up and out of the pipe. But NASA said the rover would take more pictures if the lighting was better before sealing the tube and putting it in the belly.

“We did what we came for,” said Jennifer Trosper, the mission’s project manager, in the press release. “We’re going to work through these little hiccups with the lighting in the images and we are encouraged that there is a sample in this tube.”

One of the main jobs of Perseverance is to collect rocks and soil that will eventually be returned to Earth from another mission so that scientists can exhaustively examine them with state-of-the-art instruments in their laboratories, as they did with the moon rocks from the Apollo and Soviet missions of the 1960s and 70s.

What the scientists and engineers didn’t want was a repeat of August 6th when Perseverance first drilled, collected, and sealed a rock sample. Everything seemed to be going just fine – except that the tube was empty.

“It was definitely a bit of desperation,” said Kenneth A. Farley, professor of geochemistry at the California Institute of Technology and project scientist for the mission, in an interview prior to the final drill attempt. “Everyone was so ready to declare victory. And then someone said: ‘Yes, there is a picture here, there is nothing in the tube.’ It was very sobering. “

The rover looked around with its cameras and saw if the rock core had somehow fallen to the ground. But there was no trace of it. The rock sample had apparently disappeared.

The main concern was that Perseverance’s intricate drilling mechanism had suffered a crippling malfunction and was unable to collect samples at all. But after reviewing the data, the engineers and scientists concluded that it was not the rover but the rock that was to blame.

“The rock just wasn’t our kind of rock,” wrote Ms. Trosper on August 19 in a NASA blog post. The rover’s systems had worked as expected – “pretty well actually,” wrote Ms. Trosper – but the rock was too fragile.

“The drilling resulted in the rock breaking into powder and small fragments of material that were not retained in the pipe because of their size,” said Ms. Trosper.

Dr. Farley admits there have been warning signs that August Rock may not have been the best to try first. Its brown color indicated rust, it contained salts and was full of holes. That meant it had stood in a lake or groundwater for a very long time. That was possibly a fantastic scientific find. The mineralogical changes caused by water could light up billions of years ago when Mars was wet and habitable.

But even a rusty, salty stone filled with holes can be very brittle. “We learned a lesson,” said Dr. Farley.

The operation on August 6 was not a complete loss. The tube contains sealed, uncontaminated Martian air that the scientists planned to collect at another time.

For the second attempt at drilling on Wednesday, the rover drove about 400 meters up a ridge that was slightly higher than the surrounding landscape, “and we picked the hardest rock you could find up there,” said Dr. Farley. Nicknamed Rochette, this boulder has stood the test of time and has not been wind eroded, strong evidence that it is not crumbly.

The boulder looks like a piece of hardened lava that can be accurately dated. In this way, scientists can determine the age of this boulder and determine the age of lower, older strata.

“This was a high quality goal,” said Dr. Farley.

It will be more than a decade before Dr. Farley and other scientists get their hands on it. Persistence will likely at some point drop the hermetically sealed tubes onto the Martian surface, waiting to be picked up by a future rover that is still on the drawing board.

This rover will take the rock samples to a small rocket that will take the samples on a trip back to Earth, but they won’t arrive until the 2030s.

Persistence will continue to explore a 45 kilometer wide crater called Jezero, specifically an old, parched river delta along the western edge. The rover is escorted by a small robotic helicopter called Ingenuity, which was added to the mission to test its ability to fly through the thin air of Mars.

While NASA had planned to leave Ingenuity behind after a series of test flights, it proved so successful that the helicopter, along with Perseverance, continued to follow and act as a scout of the terrain ahead. And it also improves the rover’s scientific mission.

The scientists planned to visit a place that looked impressive in pictures from orbit. “Then we looked at the helicopter pictures,” said Dr. Farley and was less impressed.

“We’re going to save a lot of time by not going there,” he said.