The WISE In-orbit Calibration - art. no. 70161N

The Wide-field Infrared Survey Explorer mission will be executed by an earth-orbiting spacecraft carrying an infrared telescope cooled by a solid hydrogen cryostat. The purpose of the mission is to conduct an all-sky survey at infrared wavelengths of 3.3, 4.7, 12 and 23 microns. The 7-month period of on-orbit operations includes one month of in-orbit checkout (IOC) and 6 months of all-sky survey scans from a dawn/dusk sun-synchronous orbit. The 30-day IOC is divided into two parts by the ejection of the telescope aperture cover some two weeks after launch. The first half of the IOC phase is primarily allocated to bus characterization; the latter half will be dedicated to cover-off instrument calibrations. In this discussion, we provide a description of the instrument calibrations to be conducted during IOC and how these plans will be carried out efficiently during the limited checkout period. The on-orbit instrument checkout is an extension of the overall WISE calibration plan. The duration of onboard calibration activities is limited by the lifetime of the cryogen and the need to begin the survey quickly. Key activities were selected because they must be done and can only be done in flight.