The Psyche Multispectral Imager Investigation: Characterizing the Geology, Topography, and Multispectral Properties of a Metal-Rich World.

Abstract

The Psyche Multispectral Imager ("the Imager") is a payload system designed to directly achieve or to indirectly enable the key scientific goals and optical navigation requirements of NASA's Psyche mission, which will conduct the first up-close orbital investigation of the metal-rich Main Belt asteroid (16) Psyche. The Imager consists of a pair of block redundant cameras and electronics that are mounted inside the thermally controlled spacecraft body, with a view out the spacecraft -X panel that will be nadir-pointed during nominal asteroid orbital mapping operations. The two identical Camera Heads are connected to a separate Digital Electronics Assembly (DEA) box that interfaces to the spacecraft avionics and that provides power, commanding, data processing, and onboard image storage. The Imager system shares significant heritage with imaging instruments flown on the Mars Climate Orbiter, the Mars Science Laboratory and Mars 2020 rovers, and Juno. Each camera consists of a 1600 × 1200 photosensitive pixel charge-coupled device (CCD) detector and its associated electronics, a 9-position filter wheel assembly, a compact catadioptric $f$ /2.9 telescope with a fixed focal length of 148 mm, and a sunshade to minimize stray and scattered light. The Imager CCD, filters, and optics enable broadband polychromatic (∼540 ± 250 nm) imaging plus narrowband imaging in 7 colors centered from 439 to 1015 nm. An additional neutral density filter enables protection of the CCD from direct solar illumination. Each camera has a field of view of 4.6° × 3.4° and an instantaneous field of view of 50 μrad/pixel that enables imaging of the asteroid at scales ranging from ∼35 m/pix from 700 km altitude to ∼4 m/pix at 75 km altitude. The primary camera ("Imager A") is pointed along the spacecraft -X axis, and the backup camera ("Imager B") is toed-out by 3.7° to potentially enable greater surface area coverage per unit time if both Imagers are operated simultaneously during some mission phases. Stereoscopic mapping is performed by observing the same surface regions with either camera over a range of off-nadir pointing angles.