Funky Mars Rocks Complicate NASA Rover's Sampling Dreams

NASA's Perseverance rover is investigating the immensely exciting river delta region of Jezero Crater. It has big plans to pick up some rock samples there that might hold evidence of past life. But the rocks aren't cooperating. Yet.

In a mission update this week, Denise Buckner, a student collaborator at University of Florida, detailed the trials and tribulations Perseverance is going through to try to find a good rock to sample. "Sometimes, fragile materials fracture, crack, or even crumble during the abrasion and coring process, and other rocks have tricky shapes and angles that make drilling difficult or impossible," Buckner wrote.

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The rover team had been eyeing an intriguing layered target nicknamed Betty's Rock that appeared to have fallen from an outcrop above. The rock's "jagged layers and awkward shape" foiled plans for collecting a sample from it. It was too tough to get the rover's sampling drill into place.

NASA intends to pick up the rover's samples from Mars and bring them back to Earth with a future mission. Perseverance already has a small rock collection from other areas in the crater, but anything gathered in the river delta will be particularly prized. The delta's history of water makes it a prime place to look for signs of ancient microbial life.  

"The rocks here at the ancient river delta are amazing, but so far none has been perfect for sampling Mars," the rover team tweeted on Wednesday. "Some too fragile, some too jagged, but I'm sure I'll find the right one soon – I'm not called Perseverance for nothing."

The team is looking at a different rock similar to Betty's. Buckner said the new target (called Skinner Ridge Rock) has "a much more approachable shape for potential abrasion and coring." 

Mars has always been fussy with human machines, whether it's wrecking rover wheels or throwing dust on solar panels. The rover's rock problem is more of a minor inconvenience in the grand scheme of what Mars can do. Percy won't give up on its quest for such sought-after samples.