Charge-Coupled Device Television Camera For Nasa's Galileo Mission To Jupiter

Abstract

The slow-scan television camera being built for NASA's Galileo Jupiter Orbiter spacecraft consists of a 1500 mm focal-length telescope coupled to a camera head housing a newly developed 800 x 800 element charge-coupled device (CCD) detector based on "virtual-phase" charge transfer technology. This detector results in a broadband sensitivity over 100 times that of a comparable vidicon-tube camera while also yielding improved resolution, linearity, geometric fidelity, and spectral range. In the near-Jovian radiation belts, interactions of high-energy particles with the silicon CCD result in the production of unwanted charge, and special techniques have been implemented (e.g., tantalum and quartz shielding, rapid image readout, and 2 x 2 picture-element on-chip averaging) to ensure adequate signal-to-noise performance for images acquired as close to Jupiter as five planetary radii. The images returned from Galileo will provide high-resolution (approximately 1 km) mapping coverage of most of the surface of the four large Galilean satellites of Jupiter with coverage of selected targets at resolutions as good as about 20 m. The broad spectral range of the instrument (0.4 to 1.1 Am) and the use of special methane-absorption-band filters in the near-infrared will allow study of the Jovian atmospheric structure and dynamics. Excellent off-axis light rejection and high sensitivity of the instrument will permit study of low-light-level phenomena such as lightning and aurorae on Jupiter and the Jovian ring.