| Popis: |
The Space Infrared Telescope Facility mission provides exciting pointing and control challenges. This paper describes the pointing and control subsystem (PCS) designed to meet these challenges. Cost, mass, performance and life-time drove the choice of the new solar orbit and the re-design of the telescope, spacecraft and the pointing and control subsystem. The PCS performs a number of key functions for the Observatory, including pointing to and holding inertial targets, tracking moving targets, performingprescribed motion patterns, maintaining pointing constraints and providing safe hold during failure. To attain the high precision demanded by the observatory, the PCS relies on a sub-arcsecond star tracker and a 0.001 arcsecond resolution inertial reference unit. An affordable PCS is realized by locating the fine guidance sensor externally, utilizing a simple fault protection strategy, and maximizing the commonality inthe use of hardware and in the development of flight software. |
