To sample or not to sample


One of the primary goals of the Perseverance mission is to collect a diverse cache of rock samples for eventual return to Earth. Among the highest priority rocks to sample are those that make up the well-preserved delta located on the west side of Jezero Crater. This delta was one of the main attributes that made this landing site so attractive for the search for ancient Martian life. Careful examination of deltaic rocks is essential to interpret their depositional environment and establish whether this paleoenvironment may have been habitable.

Mars Perseverance Sol 424 – Right Camera Mastcam-Z: Mastcam-Z image of rocks at Enchanted Lake. Credits: NASA/JPL-Caltech/ASU. Download picture ›

Since landing in Jezero Crater last year, the rover has surveyed and drilled rocks from the crater floor to add to the sample cache. But the rover hadn’t yet had access to the coveted delta rocks – until now, of course. After making a “quick traverse” to the delta, Perseverance finally arrived at the front of the delta. Last week, the rover parked at a site called Enchanted Lake, where the team hoped to sample delta rocks for the very first time. But the rover can only collect a finite number of samples. The team must therefore weigh all options carefully, keeping in mind what has already been sampled and also trying to anticipate what we might encounter along the rest of the traverse. Although we are eager to drill in the delta, we have to be judicious.

So our first action at Enchanted Lake was to examine the rocks using the rover’s remote scientific instruments to decide if they meet the desired sampling criteria. The rocks at this site had many distinct – and interesting! – compared to the others we have studied so far in Jezero. However, after a thorough evaluation, the team decided to forego sampling at this location. It was a difficult decision to make, but we are optimistic about the opportunities that lie ahead. Rather, the data collected at Enchanted Lake will be used to set the context for future delta investigations.

The rover is now heading east toward a place called Hawksbill Gap, another promising spot for delta sampling. While traversing the front of the delta, Perseverance will continue to collect data to help characterize the contact between the crater floor and the delta rocks before ascending the delta itself. But our long-awaited sample of delta rocks? For that we will have to wait a little longer.

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