The Mars Perseverance rover's sample collection has run into a snag. NASA reports the rover stopped caching samples after debris partly blocked the bit carousel (the device that stores drill bits and passes sample tubes for internal processing). The rover encountered the anomaly on December 29th, but the mission team had to wait until January 6th to send a command to extract the drill bit, undock the robot arm from the carousel and take images to verify what happened. The obstacles are believed to be pebbles that fell out of the sample tube when dropping off the coring bit, preventing that bit from sitting neatly in the carousel. The storage is crucial for NASA's plans to eventually return the samples to Earth.