When it landed on Mars in February of 2021, the Perseverance rover joined a small armada of robotic explorers working hard to characterize Mars’ environment and atmosphere and determine if it ever supported life. But unlike its predecessors, one of the key objectives of the rover is to obtain samples of Martian soil and rock, which it will leave in a cache for later retrieval by a joint NASA-ESA mission.
This will be the first sample return from Mars, and the analysis of these samples will provide new insight into the geological and environmental evolution of Mars. The first attempt to obtain a sample didn’t go so well, with the sample crumbling before it was placed in the cache. Undeterred, the science team moved onto the next site and prepared to try again. A few days ago, NASA confirmed that the rover succeeded in its second attempt and has the pictures to prove it!
The mission team was notified about the successful retrieval of the core sample on Sept. 1st, after two days of preparation and weeks of driving. To ensure that the retrieval went as planned, the mission team took additional photos of the drill site and the sample tube before transferring the tube into the rover chassis for assessment and processing. This is not standard procedure, but the team insisted on adding this extra step after the rover’s failed in its first attempt.
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The first attempt to procure a drill sample took place on August 5th, where the rover’s Sample Caching System (SCS) employed its three robotic elements to drill and procure a sample of Martian rock. The first is the five-jointed robotic arm that can reach up to 2-meters (7 feet) from the rover and carries a large turret with a rotary percussive drill. The second element is the bit carousel, which provides the drill bits and empty sample tubes to the drill.
This same element is also responsible for transferring sample-filled tubes into the rover’s chassis, where they are assessed and processed. The third is the 0.5-meter (1.6-foot) sample handling arm (aka. the “T-Rex Arm”) that is located in the rover’s underbelly and is responsible for moving sample tubes between storage and documentation stations, as well as the bit carousel.
Initially, data sent back from the rover’s percussive drill indicated that it had successfully drilled a core sample. However, hours later, the team was notified by the SCS that the sample tube was empty once it was placed back in the rover’s chassis. It was eventually deduced that the coring sample was too powdery and fell apart between being removed from the ground and put into a tube and stored inside the SCS.
The target for the second sample collection was a large rock the team nicknamed “Rochette,” which is located along a ridgeline known as “Artuby.” This ridgeline is more than 900 meters (984.25 yards) long and borders two geologic units believed to contain the deepest and most ancient layers of exposed bedrock in the Jezero Crater. The data received from the rover on Sept. 1st confirmed that Perseverance had successfully cored a sample from the rock.
Ordinarily, the rover’s science team would not obtain additional imagery before sealing and storing a Martian coring sample. However, given what happened during the previous attempt on Aug. 5th, the team decided that extra assurance was necessary. To this end, Perseverance maneuvered the corer, bit, and open end of the sample tube to be imaged by the rover’s Mastcam-Z instrument.
The initial images showed the end of an intact cored rock within the sample tube, but the team decided to inspect the tube again after clearing it. This involves a procedure known as “percuss to ingest,” which vibrates the drill bit to clear the lip of the sample tube of any residual material. Once this was done, the rover took the second set of Mastcam-Z images (seen above). The light was poor in the second one, and the interior of the sample tube was not visible.
Another round of images was taken on Sunday, Sept. 3rd, which were returned to Earth on the following day. Although the Perseverance team is confident that the sample has been successfully retrieved, additional confirmation is desired at this point. As Jennifer Trosper, the project manager at NASA’s Jet Propulsion Laboratory said in a recent NASA statement:
“The project got its first cored rock under its belt, and that’s a phenomenal accomplishment. The team determined a location, and selected and cored a viable and scientifically valuable rock. We did what we came to do. We will work through this small hiccup with the lighting conditions in the images and remain encouraged that there is sample in this tube.”
On Sept. 7th, the titanium sample tube was transferred into the rover’s interior, where the mission team used the rover’s interior instruments to measure and image the rock core. It then hermetically sealed the tube ((serial number 266), took another image, and stored the tube. As you can see from the images acquired (shown above), the sample is about the thickness of a pencil and is now stowed inside the rover’s chassis. Said Thomas Zurbuchen, the associate administrator for science at NASA HQ:
“For all of NASA science, this is truly a historic moment. Just as the Apollo Moon missions demonstrated the enduring scientific value of returning samples from other worlds for analysis here on our planet, we will be doing the same with the samples Perseverance collects as part of our Mars Sample Return program. Using the most sophisticated science instruments on Earth, we expect jaw-dropping discoveries across a broad set of science areas, including exploration into the question of whether life once existed on Mars.”
Since then, scientists have been using Perseverance’s instruments to analyze Rochette itself. The sample itself will be examined back once it is returned to Earth, where it can be examined using instruments that are far too large to place on a rover. The analysis of these samples is expected to teach scientists a great deal about the early geological history and evolution of Mars, including how it ceased being the warmer and wetter place it once was.
“With over 3,000 parts, the Sampling and Caching System is the most complex mechanism ever sent into space,” said Larry D. James, the interim director of NASA JPL. “Our Perseverance team is excited and proud to see the system perform so well on Mars and take the first step for returning samples to Earth. We also recognize that a worldwide team of NASA, industry partners, academia, and international space agencies contributed to and share in this historic success.”
This initial phase of the rover’s science operations will conclude once the rover has filled eight of its 43 sample tubes and returned to where it first landed – the Octavia E. Butler Landing Site. At that point, the rover will have traveled a distance of between 2.5 and 5 km (1.6 and 3.1 mi) since it arrived on Mars. After that, Perseverance will travel to the location of its second science campaign: Jezero Crater’s delta region.
This fan-shaped feature constitutes the remains of the spot where an ancient river emptied into a lake within the crater, slowly depositing sediment over time. This region is expected to be rich in clay minerals, which are associated with biological processes here on Earth and could contain the fossilized remains of ancient, microscopic life. If life existed on Mars billions of years ago (before it lost its atmosphere and surface water), delta fans are a good place to look for their remains.
On Friday, Sept. 10th, NASA will be holding a briefing to discuss its mission milestone and update the public on the progress of the Perseverance mission. The discussion panel will also address what the rover’s instruments have learned about Rochette and the implications this milestone will have for the sample retrieval mission NASA and the ESA have planned. Known as the Mars Sample Return campaign, which could launch as soon as 2026.
Further Reading: NASA