Operations and calibration of the solid-state imaging system during the Galileo extended mission at Jupiter

Abstract

The solid state imaging (SSI) subsystem on the National Aeronautics and Space Administration's (NASA's) Galileo spacecraft has successfully completed a 4-yr extended mission exploring the Jovian system. The SSI remained in stable calibration throughout its total 12-yr flight time and returned valuable scientific data until the end of the mis- sion. A slight loss in spatial resolution occurred between the last primary- mission calibration and that done during the extended mission. The ab- solute spectral radiometric calibration has been determined to 5 to 7% accuracy across the camera's eight spectral filters. A possible shift in the central wavelength of one of the methane-absorption-band filters of ;3 nm shortward may have occurred late in the extended mission. The charge-coupled device (CCD) detector endured the harsh radiation en- vironment at Jupiter to a total dose of ;4 krad without any serious per- manent damage. Some radiation-induced problems in the detector clock- ing and signal-chain electronics rendered the 2-32-pixel summation modes unusable and required that the CCD light flood and erasure prior to each exposure be disabled. However, good-quality imaging continued to be possible even in the most extreme radiation fluxes encountered. The successful return of 1453 images during the extended mission nearly matched the number of frames returned during the primary mission. © 2003 Society of Photo-Optical Instrumentation Engineers.