The SHERLOC Calibration Target on the Mars 2020 Perseverance Rover: Design, Operations, Outreach, and Future Human Exploration Functions

The Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) is a robotic arm-mounted instrument onboard NASA’s Perseverance rover. SHERLOC combines imaging via two cameras with both Raman and fluorescence spectroscopy to investigate geological materials at the rover’s Jezero crater field site. SHERLOC requires in situ calibration to monitor the health and performance of the instrument. These calibration data are critically important to ensure the veracity of data interpretation, especially considering the extreme martian environmental conditions where the instrument operates. The SHERLOC Calibration Target (SCT) is located at the front of the rover and is exposed to the same atmospheric conditions as the instrument. The SCT includes 10 individual targets designed to meet all instrument calibration requirements. An additional calibration target is mounted inside the instrument’s dust cover. The targets include polymers, rock, synthetic material, and optical pattern targets. Their primary function is calibration of parameters within the SHERLOC instrument so that the data can be interpreted correctly. The SCT was also designed to take advantage of opportunities for supplemental science investigations and includes targets intended for public engagement. The exposure of materials to martian atmospheric conditions allows for opportunistic science on extravehicular suit (i.e., “spacesuit”) materials. These samples will be used in an extended study to produce direct measurements of the expected service lifetimes of these materials on the martian surface, thus helping NASA facilitate human exploration of the planet. Other targets include a martian meteorite and the first geocache target to reside on another planet, both of which increase the outreach and potential of the mission to foster interest in, and enthusiasm for, planetary exploration. During the first 200 sols (martian days) of operation on Mars, the SCT has been analyzed three times and has proven to be vital in the calibration of the instrument and in assisting the SHERLOC team with interpretation of in situ data.