Observatory design for the imaging X-Ray Polarimetry Explorer (IXPE) mission

The goal of the Imaging X-Ray PolarimetryExplorer (IXPE) Mission is to expand understanding of high-energy astrophysicalprocesses and sources, in support of NASA's first science objective in Astrophysics: “Discover how the universe works.” Polarization uniquely probes astrophysicalanisotropies — ordered magnetic fields, aspheric matter distributions, or general relativistic coupling to black-hole spin — that are not otherwise measurable. IXPE will conduct X-ray polarimetryfor multiple categories of cosmic X-ray sources that are likely to be polarized such as neutron stars, stellar-massblack holes, supernova remnantsand active galactic nuclei. The IXPE Observatoryconsists of Spacecraftand Payloadmodules built up in parallel to form the Observatoryduring system integration and test. The Payloadincludes three polarization-sensitive, X-ray detectors, each paired with its corresponding grazing incidence mirror module assembly (MMA). A deployable boom provides the correct separation (focal length) between the detector units (DU) and MMAs. These Payloadelements are supported by the IXPE Spacecraftwhich is derived from the BCP-100 small Spacecraftarchitecture. This paper summarizes the IXPE mission science objectives, describes the Observatoryimplementation concept including the payloadand spacecraftelements and summarizes the expected conceptof operations.