Design and development of the mars observer camera

Abstract

AbstractThe Mars Observer Camera (MOC) consists of three integrated optical subassemblies (one narrow‐angle and two wide‐angle cameras) with common electronics, designed to take high‐spatial‐resolution pictures of the surface of Mars and lower‐spatial‐resolution, synoptic coverage of the planet's surface and atmosphere. It incorporates several advanced technologies, including the use of graphite/epoxy structural materials, 32‐bit microprocessors, 108‐bit digital buffers, and high‐speed custom integrated circuits. The cameras use the “push broom” technique to build pictures, one line at a time, as the spacecraft orbits the planet. The narrow‐angle camera can acquire images of areas ranging from 2.9 × 2.9 km2 to 2.9 × 25.2 km2 at a resolution of 1.4 m/pixel. Additionally, lowerresolution pictures (to a lowest resolution of about 11 m/pixel) can be acquired through the narrow‐angle camera by pixel averaging; these images can be much longer (up to 2.9 × 500 km at 11 m/pixel). The wide‐angle cameras are capable of viewing Mars from horizon to horizon and, in a single 24‐hour period, can acquire a complete global image of the planet at a resolution of at least 7.5 km/pixel. Regional areas (covering hundreds of kilometers on a side) may be photographed at a resolution of better than 250 m/pixel at the nadir. The two wide‐angle cameras image through a different spectral filter, allowing the construction of color images. The MOC is a cylinder 88 cm in length and about 40 cm in diameter; the redundant electronics, equivalent in complexity and computational power to two engineering workstations, fit within a volume 40 cm in diameter and 10 cm long behind the narrow‐angle primary mirror. NASA's Mars Observer mission has adopted a distributed operations philosophy: all uplink and downlink activities for the MOC and the other payload experiments will occur remote from the Jet Propulsion Laboratory's command centers. Following its year‐long flight to Mars (launch is scheduled for 16 September 1992), Mars Observer is planned to acquire data for one Mars year (687 Earth days). During that time, MOC will acquire about 2 × 1012 bits of image and engineering data. During the last three months of the mission, Mars Observer will use a French‐supplied relay system to acquire an additional 2 × 109 bits of data from balloons deployed as part of the Soviet Mars '94 mission. These data will be collected and transferred to the Earth through the MOC electronics.