NASA’s Persevering Mars rover is preparing for another attempt, in the coming weeks, to collect Martian rocks after its first attempt earlier this month wasn’t what engineers expected. Engineers say the rover’s sampling arm worked, but the sampling tube appeared empty.
Now, it will drive the rover, a science laboratory on wheels that landed on Mars in February, to a new location called Citadelle for a second shot of capturing its first rock sample. This time, to make sure the sample was actually collected, the engineers would wait for the sample tube images to come back before they were processed and stored inside the rover’s belly.
“We were so excited because the devices worked from start to finish without any errors. Then there was that surprise—no sample? What do you mean no sample?” Louise Gandora, chief engineer for sampling and caching on NASA’s Perseverance Team, says of the attempt. The first is on August 5th. “Quickly, then, we started the investigation.”
The rock in which the perseverance drill samples were dug was not as strong as scientists thought. What was supposed to be a fairly hard rock core turned out to be a crumbly powder that slipped out of the rover’s sampling tube. After finding the sample tube was empty, the expedition crew used the rover’s cameras to analyze the remains of the hole dug by Perseverance. They discovered the pile of dust around the crater and that some material at the bottom of the crater had slipped.
“Rocks simply weren’t our type of rock,” Jennifer Trosper, project manager at NASA’s Jet Propulsion Laboratory, wrote in a blog Thursday. “Although we managed to get over 100 positions in a range of different test rocks on Earth, we never encountered a rock in our test group that behaved exactly that way.”
The seven-foot-long, five-joint tenacity sampling arm extends from the front of the rover toward an important rock with a large shoebox-sized head or tower at the end weighing 100 pounds. This head packs a hollow drill bit, officially called a Rotary Drill Bit, which drills into the rocks and traps the material inside the tube, which is stored back in the rover and processed inside another tube until it’s ready to be left somewhere on the surface of Mars.
The drill bit used in the first sampling attempt from Perseverance is to collect the rock core. Some of the rover’s nine drill bits are better suited for collecting regolith – the most crumbly, dirt-like material that engineers accidentally encountered during the first sampling attempt.
The Perseverance mission to collect up to 35 samples of Martian rocks is the first stage of a three-dimensional quest to return those samples to Earth sometime in the 1930s. The rocks, stored inside tiny sample tubes the size of chalk, will represent the first samples of pristine Mars captured and returned to Earth by humans. Perseverance will leave tubes somewhere on the surface of Mars to collect a future NASA robot and launch into Mars orbit, where it will be picked up by another ESA-built spacecraft and carried home.
NASA engineers spent nearly a decade designing and building the rover’s sampling system, which Perseverance Chief Engineer Adam Seltzner described as “the most complex and complex thing we know how to build.”