After failing on its first attempt to collect a sample of Martian soil for eventual return to Earth, Perseverance has successfully scooped a sample on its second attempt. This marks the first time a sample has been recovered on the planet. However, it won't be making the interplanetary journey for analysis any time soon. Any hints of ancient life on Mars it might reveal will have to wait.
Despite the increasing sophistication of the analytical devices on board the Mars rovers, their capacities lag a long way behind laboratories on Earth. Consequently, part of Perseverance's mission is to take samples from particularly interesting-looking rocks or rubble, storing each in one of its 43 sample tubes. At some point in the future, tentatively scheduled for 2026-31, a mission will visit Mars that will be capable of making a round trip, bringing Perseverance's collection home.
Way back on August 5, Perseverance drilled a neat little core hole for its first sample. However, on August 6, NASA acknowledged “One of the steps that occurs after placing a probe into the collection tube is to measure the volume of the sample. The probe did not encounter the expected resistance that would be there if a sample were inside the tube.” It appeared the sample had disappeared. Now it has had more luck.
At a site 800 meters (0.5 miles) or so from where the first attempt was made, Perseverance tried again. This time the results were reported as a success by NASA. “The team determined a location, and selected and cored a viable and scientifically valuable rock. We did what we came to do,” project manager Jennifer Trosper said.
Scientists involved with the mission were more effusive on social media.
The previous failure is now attributed to the first sample having been from an insufficiently robust rock so this time Perseverance selected a more solid target, choosing a rock NASA calls “briefcase-sized” that sits on a ridgeline full of outcrops and boulders.
Even so, not everything ran smoothly. Perseverance’s first images show the sample intact and present in the tube, but follow-up images were inconclusive. It is thought better lighting is needed, so Perseverance will wait most of a Martian day to photograph the sample again in better light. Nevertheless, the evidence from the first images is considered strong enough the mission team is confident that the sample is in the tube, NASA says.
Slipping a core sample into a storage tube might seem an easy task, and the initial problems certainly make the case for why there are advantages in sending humans, despite the much higher cost. Nevertheless, explained NASA systems engineer Dr Rachel Kronyak, collecting a sample is a multi-stage process that can take a week. In particular, once a core has been taken Perseverance must “Deliver the core (inside its sample tube) to the belly of the rover, where it goes through a complex sequence of sample assessment, imaging, hermetic sealing, and eventual storage.”
The first effort was not considered a total failure, with a NASA statement, noting: “The first sample tube still contains a sample of Martian atmosphere, which the mission had originally planned to acquire at a later time.” This is just the first of many sample collections for Perseverance. It has 43 containers, after all. The hope is to sample as many environments as possible while it's there, as the only samples we have of Mars are from meteorites.