Imaging X-ray polarimetry explorer mission overview and systems engineering status

Abstract

The Imaging X-ray Polarimetry Explorer (IXPE) is a space-based observatory that will have the capability to measure the polarization of X-rays from astrophysical sources. IXPE will improve sensitivity over OSO-8, the only previous X-ray polarimeter, by two orders of magnitude in required exposure time. IXPE will yield insight into our understanding of X-ray production in objects such as neutron stars as well as stellar and supermassive black holes. IXPE measurements will provide new dimensions for probing a wide range of cosmic X-ray sources — including active galactic nuclei (AGN) and microquasars, pulsars and pulsar wind nebulae, magnetars, accreting X-ray binaries, supernova remnants, and the Galactic center. Addressing NASA's Science Mission Directorate's science goal “to probe the origin and destiny of our universe, including the nature of black holes, dark energy, dark matter, and gravity.” IXPE will introduce the capability for X-ray polarimetric imaging, uniquely enabling the measurement of X-ray polarization with scientifically meaningful spatial, spectral, and temporal resolution. These polarization measurements will help answer fundamental questions regarding 1) the geometries of the flows, emission regions, and magnetic fields, 2) the physical process that lead to particle acceleration and X-ray emission, and 3) the physical effects of gravitational, electric, and magnetic fields at their extreme limits. This scientific mission, IXPE, is being developed by the NASA Marshall Space Flight Center (MSFC), Ball Aerospace, the Italian Space Agency (ASI), the Institute for Space Astrophysics and Planetology (IAPS)/ National Institute of Astrophysics (INAF), the National Institute for Nuclear Physics (INFN), the University of Colorado Laboratory for Atmospheric and Space Physics (LASP), Stanford University, McGill University, and the Massachusetts Institute of Technology. The IXPE partners each provide unique capabilities and experience which are utilized to design, build and launch the IXPE observatory resulting in the collection of on-orbit scientific data measurements which are transmitted to ground stations and analyzed. The established systems engineering (SE) methods and teaming approach to achieve the IXPE mission goals will be discussed. For this paper, the focus is the IXPE observatory and the collaboration of NASA MSFC, Ball Aerospace and IAPS/INAF. Our current focus is on requirements development and analysis along with definition of the interface control documents (ICD). Of particular note are requirements and ICDs between major flight elements and between organizations. This paper will describe the SE philosophy being used to ensure complete inter-organizational understanding and agreement as the Project moves towards SRR in September 2017 and PDR in June 2018. Current status and future milestones will be discussed.