Use of a passive reaction wheel jitter isolation system to meet the Advanced X-Ray Astrophysics Facility imaging performance requirements
Third in the series of NASA great observatories, the AXAF is scheduled for launch from the Space Shuttle in November of 1998. Following in the path of the Hubble Space Telescope and the Compton Gamma Ray Observatory, this observatory will image light at x-ray wavelengths, facilitating the detailed study of such phenomena as supernova and quasars. The AXAF project is sponsored by the NASA Marshall Space Flight Center in Huntsville, Alabama. Because of exacting requirements on the performance of the AXAF optical system, it was necessary to reduce the transmission of reaction wheel jitter disturbances to the observatory. This reduction was accomplished via use of a passive mechanical isolation system to interface the reaction wheels with the spacecraft central structure. In addition to presenting a description of the spacecraft, the isolation system, and the key image quality requirement flowdown, this paper details the analyses performed in support of system-level imaging performance requirement verification. These analyses include the identification of system-level requirement suballocations, formulation of unit-level isolation system transmissibility requirements, and quantification of imaging performance. Given in comparison to the non-isolated system imaging performance, the result of these analyses clearly illustrate the effectiveness of an innovative reaction wheel passive isolation system.