Perseverance Has Pebbles Stuck in its Sample Caching System

The Perseverance rover has already made history by collecting the first-ever rock cores on another planet, but NASA says a pebble problem has delayed operations. The rover’s advanced sample collection mechanism has become obstructed by some debris, and the team doesn’t want to continue until it can get the rocks out of the way and ensure there is no damage to this irreplaceable scientific resource.

Perseverance landed on the red planet almost a year ago, following in the tire tracks of Curiosity. While the two rovers share the same chassis, Perseverance has a more advanced camera suite, a helicopter buddy, and the Sample Caching System. With the caching system, Perseverance can collect several dozen rock cores from Mars and store them in sealed containers. Eventually, another mission will arrive to pick up the tubes and send them into orbit. There, a third mission will pick up the payload and ferry the samples back to Earth.

Before any of that can happen, Perseverance has to collect the samples. This has never been done before — as NASA points out, only six rock cores have ever been drilled on another planet, and all of them were Perseverance. That’s why NASA wants to move forward very carefully to address this issue.

NASA initially got data suggesting there was an obstruction in the rover’s bit carousel. This is where the nested sample tube is removed from the drill bit. During previous sampling procedures, the coring bit traveled 5.15 inches before sensors detected resistance. When unloading the seventh sample, the sensor recorded higher resistance 0.4 inches sooner. The team pinged the rover for additional data, but Mars is on the other side of the solar system right now. In this period of “restricted sols,” it took several days to get a handle on what’s wrong.

Data from the rover shows several small rocks lodged in the bit carousel. The team is confident these pebbles came from the sample tube as it was being transferred. The designers of the carousel took into account the possibility that debris could collect in this area, but everything happening up there is a first for humanity. The team is going to take time to assess the situation and ensure the pebbles are cleared safely. Once that’s done, the team expects Perseverance will be ready to “hit the un-paved Martian road again.”

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