The Mars Science Laboratory Curiosity rover Mastcam instruments: Preflight and in-flight calibration, validation, and data archiving

The NASA Curiosity rover Mast Camera (Mastcam) system is a pair of fixed-focal length, multispectral, color CCD imagers mounted similar to 2m above the surface on the rover's remote sensing mast, along with associated electronics and an onboard calibration target. The left Mastcam (M-34) has a 34mm focal length, an instantaneous field of view (IFOV) of 0.22mrad, and a FOV of 20 degrees x15 degrees over the full 1648x1200 pixel span of its Kodak KAI-2020 CCD. The right Mastcam (M-100) has a 100mm focal length, an IFOV of 0.074mrad, and a FOV of 6.8 degrees x5.1 degrees using the same detector. The cameras are separated by 24.2cm on the mast, allowing stereo images to be obtained at the resolution of the M-34 camera. Each camera has an eight-position filter wheel, enabling it to take Bayer pattern red, green, and blue (RGB) true color images, multispectral images in nine additional bands spanning similar to 400-1100nm, and images of the Sun in two colors through neutral density-coated filters. An associated Digital Electronics Assembly provides command and data interfaces to the rover, 8Gb of image storage per camera, 11bit to 8bit companding, JPEG compression, and acquisition of high-definition video. Here we describe the preflight and in-flight calibration of Mastcam images, the ways that they are being archived in the NASA Planetary Data System, and the ways that calibration refinements are being developed as the investigation progresses on Mars. We also provide some examples of data sets and analyses that help to validate the accuracy and precision of the calibration. Plain Language Summary We describe the calibration and archiving of the images being obtained from the Mastcam multispectral, stereoscopic imaging system on board the NASA Curiosity Mars rover. Calibration is critical to detailed scientific analysis of instrumental data, and in this paper we not only describe the details of the calibration process and the steps in our resulting data calibration pipeline but also present some examples of the kinds of scientific analyses and discoveries that this calibration has enabled.