What The project is part of NASA's Mars 2020 Rover Mission, aiming to identify, select, drill and cache samples of high scientific value for later return to Earth by a joint NASA/ESA mission. Supported by the Carlsberg Foundation, the Niels Bohr Institute at UCPH has provided a set of radiometric reference calibration targets for the main camera of the Mars rover, Mastcam-Z. Mastcam-Z is a zooming stereo-camera for reconnaissance, spectroscopy and planning of traverses. The camera can record visible and near infrared spectra, but without precise calibrations, quantitative interpretation of the radiometric data would not be possible. Using codes by Kjartan Kinch all spectroscopic data will be calibrated using these targets and we will use this data to support science and operations on Mars. Why NASA’s 2020 Mars Rover is the first to actively select samples from known context at a well characterised site on Mars for later return to Earth. The Danish provided calibration targets will make Mastcam-Z a truly quantitative scientific instrument for visual and near infrared spectroscopy. Mastcam-Z will be the main reconnaissance instrument to help select the most promising samples to return for detailed investigation. These investigations include precise dating based on radioactive isotopes and search for potential biosignatures from extinct or extant microorganisms. In this way NASA’s Mars 2020 Rover mission may provide the first answers to important questions about prevalence of life in the Solar System. This is the first step towards establishing whether we are alone in the Universe. How The research will be conducted using data directly returned from Mars – at first from the Science Operations Center at NASA’s Jet Propulsion Laboratory in California – later remotely from the Niels Bohr Institute, UCPH. As Co-Investigators select Danish scientists have full and immediate access to all scientific data from the mission, and activities include operations of the instruments on Mars, analysis and calibration of received data, scientific interpretation of data and its context and publications. In addition to performing the first ever exploration of a well-preserved delta in Jezero crater on Mars, the project will produce a scientific legacy consisting of characteristics of each cached sample. This will hopefully serve as a very compelling incentive to bring them back to Earth. SSR The collected samples will be returned to Earth for detailed investigations and scrutiny. This will initiate decades of studies of these unique samples and will inevitably inspire new future scientists. The returned samples will contribute knowledge about the prevalence of life in the Universe and thereby bring a new perspective to life on Earth. They will help synchronise the clocks that measured the evolution of the Solar System. Finally, when the city of Copenhagen and most of Denmark is eroded by the glaciers of the next ice age, NASA’s Mars 2020 Rover and the calibration targets contributed by Denmark will be somewhat dusty. But, below a thin veneer of reddish dust they will appear almost as pristine as when they arrived in 2021 leaving Earthly greetings to future explorers of Mars.