Imaging X-Ray Polarimetry Explorer Mission: Spacecraft Implementation Concept

摘要

The goal of the Imaging X-Ray Polarimetry Explorer (IXPE) Mission is to expand understanding of high-energy astrophysical processes and sources, in support of NASA's first science objective in Astrophysics: "Discover how the universe works." Polarization uniquely probes physical anisotropics—ordered magnetic fields, aspheric matter distributions, or general relativistic coupling to black-hole spin—that are not otherwise measurable. X-ray polarimetry is the focus of the IXPE science mission. The IXPE Observatory consists of Spacecraft and Payload modules built up in parallel to form the Observatory during system integration and test The Payload includes three polarization sensitive, X-ray detector arrays, each paired with its cooresponding grazing angle incidence mirror module assemblies (MMA). A deployable boom provides the correct separation (focal length) between the detector units (DU) and MMAs. These Payload elements are supported by the IXPE Spacecraft which is derived from the BCP-100 small Spacecraft architecture. The BCP-100 uses flight-proven components, a simple structural design, and significant design and software reuse from prior missions. The Spacecraft design provides the required power over the full range of sun angles. A star tracker is a key element of the attitude determination and control system. It is mounted directly with the Payload to minimize alignment errors between the bus and Payload. The modular design allows for concurrent Payload and Spacecraft development with a well-defined, clean interface to reduce technical and schedule risk. The design balances a low-cost and low-risk approach with significant Spacecraft capability and flexibility. This paper summarizes the IXPE mission science objectives, instrument and Observatory concepts and then describes IXPE Spacecraft implementation.