Imaging X-Ray Polarimetry Explorer (IXPE) - One Year On-Orbit

The Imaging X-Ray Polarimetry Explorer (IXPE) is designed 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 measurements and imaging are key capabilities of the IXPE observatory. IXPE, an international collaboration between NASA and the Italian Space Agency (ASI), is a NASA Small Explorer designed as a 2- year mission. It launches to a circular LEO orbit at an altitude of 600 km and an inclination of similar to 0 degrees on a Falcon 9 launch vehicle. The payload uses a single science operational mode to capture the X-ray data from the science targets. The mission design follows a simple observing paradigm: pointed viewing of known X-ray sources (with known locations in the sky) over multiple orbits (not necessarily consecutive orbits) until the observation is complete. IXPE's payload is a set of three identical, imaging, X-ray polarimetry telescopes mounted on a common optical bench and co-aligned with the pointing axis of the spacecraft. The BCPSmall spacecraft provides the necessary resources to support and operate the payload elements and enable continuous science data collection. The Observatory communicates with ground stations via S-band link. The ground system consists of three major elements: the ground stations for data receipt and command upload to the Observatory; the Mission Operation Center (MOC); and Science Operations Center (SOC). Launch occurred on 9 December 2021. The IXPE Observatory has been collecting science data from cosmic X-ray sources since 11 January 2022. These include extreme astronomical objects, such as stellar-mass and supermassive black holes, magnetars, Blazars, neutron stars, and pulsars. This paper summarizes the IXPE mission, describes the Observatory, ground system, and commissioning and overviews recent science results.