This week’s image shows the Perseverance Mars rover looking back on its work – the depositing of 10 titanium sample tubes on the surface of the Red Planet should they be needed as backups (see image below marking the sample locations). The rover is carrying the official samples, but this depot was set up just in case something happens to the rover.
Here is a little more from NASA:
Eight of those tubes are filled with rock and regolith (broken rock and dust), while one is an atmospheric sample and one is a “witness” tube...
The depot represents a backup collection of samples that could be recovered in the future by the Mars Sample Return campaign, a joint effort between NASA and ESA (European Space Agency) that aims to bring Mars samples to Earth for closer study. The rover began building the depot on Dec. 21, 2022, precisely spacing the tubes in case they need to be retrieved at a future date.
The primary tubes reside in the belly of Perseverance, which would pass them, along with future samples taken during the mission to a Sample Retrieval Lander as part of the campaign. If anything were to happen to the rover to prevent it from delivering tubes directly to the lander, samples could be retrieved from the depot instead. (Learn more about all 18 samples taken so far.)