Robotic Operations for the First Sample Depot on Mars

The Perseverance rover has completed a very successful2.5 years on Mars. It has filled 24 of the 43 sample tubes itbrought to Mars and completed the Three Forks Sample Depoton January 28, 2023, where it deposited 10 of these samples onthe surface of Mars. Each deposited sample was sealed within aReturnable Sample Tube Assembly (RSTA) and attached gloveassembly (RGA). Creation of this sample depot has satisfied allof the prime mission requirements. The Mars Sample Returnmission aims to bring some of the samples that Perseverancecollects from Mars to Earth, either via direct delivery from thePerseverance rover to the Sample Retrieval Lander (SRL), orby deploying Sample Recovery Helicopters (SRH) to fly to thesamples and collect them. This paper describes the strategicplanning and tactical execution of the mobility, robotic arm,sampling and imaging activities that led to the very successfuldepot creation. A number of factors had to be consideredincluding SRH access, communication obstructions, view forimaging, and contingency handling. It discusses how the strategicplanning arrived at the plan for alternating two main typesof sols: drop and image, and drive and photoshoot. Drop andimage choreographed moves between the Perseverance externalrobotic arm and the Adaptive Caching Assembly (ACA) insidethe rover, which has a second robotic arm - the Sample HandlingArm - to image the sample before and after depositing it on theground. Drive and photoshoot consists of backing up and takingmid-drive images of the dropped sample. During the 42 Martiandays (sols) that it took to create and document the Three Forksdepot, the rover drove 207.93 meters, dropped 10 sample RGAs,and took 4000 images. Completion of this sample depot ensuresthat there will be samples for the Mars Sample Return missionto bring back to Earth for the first time.