On-Orbit Solar Dynamics Observatory (SDO) Star Tracker Warm Pixel Analysis

摘要

This paper describes the process of identification and analysis of warm pixels in two autonomous star trackers on the Solar Dynamics Observatory (SDO) mission. A brief description of the mission orbit and attitude regimes is discussed and pertinent star tracker specifications are given. Warm pixels are defined and several indicators of anomalous behavior, including the characteristic "inverted-U" pattern in the Quality Index parameter, indicative of warm pixels are introduced. A description of the algorithm used to identify warm pixel candidates is given. Finally, an analysis of dumps of on-orbit star tracker charge coupled device (CCD) images is presented and an operational plan going forward is discussed. This particular star tracker model has been flown on various spacecraft, including NASA and ESA missions, and is planned to be used in the future. This analysis of on-orbit SDO data has been critical to understanding the effects of warm pixels on this particular unit. Additionally, this approach should be useful on all CCD star trackers, in general.