The Mars 2020 Perseverance Rover Mast Camera Zoom (Mastcam-Z) Multispectral, Stereoscopic Imaging Investigation

Abstract

Mastcam-Z is a multispectral, stereoscopic imaging investigation on the Mars 2020 mission's Perseverance rover. Mastcam-Z consists of a pair of focusable, 4:1 zoomable cameras that provide broadband red/green/blue and narrowband 400-1000 nm color imaging with fields of view from 25.6° × 19.2° (26 mm focal length at 283 μrad/pixel) to 6.2° × 4.6° (110 mm focal length at 67.4 μrad/pixel). The cameras can resolve (≥ 5 pixels) ∼0.7 mm features at 2 m and ∼3.3 cm features at 100 m distance. Mastcam-Z shares significant heritage with the Mastcam instruments on the Mars Science Laboratory Curiosity rover. Each Mastcam-Z camera consists of zoom, focus, and filter wheel mechanisms and a 1648 × 1214 pixel charge-coupled device detector and electronics. The two Mastcam-Z cameras are mounted with a 24.4 cm stereo baseline and 2.3° total toe-in on a camera plate ∼2 m above the surface on the rover's Remote Sensing Mast, which provides azimuth and elevation actuation. A separate digital electronics assembly inside the rover provides power, data processing and storage, and the interface to the rover computer. Primary and secondary Mastcam-Z calibration targets mounted on the rover top deck enable tactical reflectance calibration. Mastcam-Z multispectral, stereo, and panoramic images will be used to provide detailed morphology, topography, and geologic context along the rover's traverse; constrain mineralogic, photometric, and physical properties of surface materials; monitor and characterize atmospheric and astronomical phenomena; and document the rover's sample extraction and caching locations. Mastcam-Z images will also provide key engineering information to support sample selection and other rover driving and tool/instrument operations decisions.

Keywords: Jezero crater; Mars; Mars 2020 mission; Perseverance rover; Space imaging; Space instrumentation.

Fig. 1

Did water flow on the surface/subsurface of Mars? Like MSL/Mastcam, Mastcam-Z’s resolution can discriminate (A) conglomerates formed in high-energy streams (Williams et al. 2013), (B) cross-bedded sandstones formed in less energetic flows (Edgar et al. 2018), and (C) lake-deposited mudstones with post-depositional circulation of subsurface fluids (Kronyak et al. 2019). These kinds of features provide context in the Mars 2020 search for habitable environments.

Fig. 2

Mastcam-Z’s near-UV, visible, and near-IR filters (Table 3) enable false color composite representations like these to detect (A) ferric/ferrous variations in coated vs. abraded surfaces (Farrand et al. 2007); (B) hematite in diagenetic concretions (Bell et al. 2004b); (C) 1000-nm absorption in hydrated soils in natural or disturbed surfaces (Johnson et al. 2007)

Fig. 3

Lab spectra (solid line; Clark et al. 2007) of Mars-relevant hydrated minerals, ferric sulfate, iron oxide, and ferrous silicates convolved to the Mastcam-Z narrowband and RGB filters (open circles). Black circles: heritage MSL/Mastcam filters (Bell et al. 2017)

Fig. 4

Mars 2020 Perseverance rover Mastcam-Z flight hardware. (Left) Flight Camera Heads (identical to each other except for different color filters in their filter wheels; Table 3), shown upside-down on temporary carrying plates. (Upper right) Flight Digital Electronics Assembly (DEA), on a temporary carrying plate. For scale, the pocket knife in the photos is 3.5 inches (88.9 mm) long. (Lower right) Flight Primary (top) and Secondary (lower) Calibration Targets, mounted on the rover deck. For scale, the primary target is 3.1 × 3.1 inches ($8\times 8$ cm) across

Fig. 5

Mastcam-Z Camera Head (Left) and DEA (Right) block diagram.

Fig. 6

CAD model renderings of the Mastcam-Z optomechanical subsystems. Inset shows the full Camera Head.

Fig. 7

(Top) Cross-sectional view of the Mastcam-Z Camera Head and optics; (Bottom) Ray trace of the Mastcam-Z optics. The movable Zoom Groups and movable Focus Lens are shown here as set at a mid-range focal length of ∼64 mm

Fig. 8

The Mars 2020 mission’s Perseverance rover, in testing at the Jet Propulsion Laboratory in July 2019. The inset shows the top of the rover’s Remote Sensing Mast assembly, with the Mastcam-Z left (ML) and right (MR) cameras as well as the rover’s two Navcams (NL, NR) and the mast unit of the SuperCam (SC) instrument, including the aperture for the Remote Micro-Imager (RMI) and other SuperCam systems (Maurice et al. ; Wiens et al. 2020). The red arrow shows the location of the Mastcam-Z Primary and Secondary calibration targets on the rover deck (see Fig. 4 and Kinch et al. 2020a)

Fig. 9

Examples of characterization and calibration images taken by the flight Mastcam-Z cameras during pre-launch testing in 2019 and 2020. (Upper left) Part of an MTF test target imaged at 100 mm focal length from a range of 7 m. The central “bow tie” feature is 5.6 cm tall; (Lower left) Part of a 57-cm diameter “Siemens star” MTF test target imaged at 34 mm focal length from a range of 5 m. (Upper and lower middle) Examples of distant targets imaged at 26 mm and 110 mm focal lengths. The houses on the top of the distant ridge are approximately 1 km away. (Right) Example 34 mm focal length 360° downward-pointing mosaic of the Perseverance rover’s deck, assembled from 53 individual 34 mm focal length images taken during ATLO testing at KSC in March 2020 for geometric mapping and RSM pointing verification

Fig. 10

Example of reconstructed and geologically interpreted 3-D stereo measurements using MSL Curiosity rover Mastcam images of the Whale Rock target at the Pahrump Hills outcrop in Gale crater. Stereo data sets like this enable the assessment of quantitative sedimentological parameters like strikes, dips, and bedding plane orientation and thicknesses that can directly inform specific past geologic origins and environments. The reconstruction here was generated using the same data visualization and analysis tools to be used for geologic interpretations of Mastcam-Z stereo image products (“PRo3D”; Barnes et al. 2018). Mastcam-Z can obtain stereo data at up to 4 times higher spatial resolution than MSL/Mastcam.