Nasa's Perseverance rover has drilled into its second rock with a view to collecting samples, after the first one strangely went missing. The space agency has chosen the rock "Rochette", located on a ridge called "Citadelle" near the Jezero Crater on the Red Planet, for examination. A drilling tool on the rover's two metre-long robotic arm will sink into the rock and transfer material into a capture tube that is only slightly thicker than a pencil. The Citadelle ridge is capped with a layer of rock that seems to be resistant to wind erosion, which means it's likely the rock will endure the pressure of drilling. This is a vital quality as Nasa's previous attempt to retrieve a sample resulted in an empty tube.