Jeff Wedmore

Bio: Jeff Wedmore is an academic researcher. The author has contributed to research in topics: Payload & Observatory. The author has an hindex of 1, co-authored 1 publications receiving 8 citations.

IXPE Mission System Concept and Development Status

Abstract: The goal of the Imaging X-Ray Polarimetry Explorer (IXPE) Mission, a NASA Small Explorer (SMEX), 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 astrophysical anisotropies—ordered magnetic fields, aspheric matter distributions, or general relativistic coupling to black-hole spin—that are not otherwise measurable. Imaging enables the specific properties of extended X-ray sources to be differentiated. IXPE will conduct X-ray imaging polarimetry for multiple categories of cosmic X-ray sources such as neutron stars, stellar-mass black holes, supernova remnants and active galactic nuclei. The Observatory uses a single science operational mode capturing the X-ray data from the targets. 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 X-ray telescopes each consisting of a polarization-sensitive, gas pixel X-ray detector, 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 payload elements are supported by the IXPE spacecraft which is derived from the BCP-small spacecraft architecture. This paper summarizes the IXPE mission science objectives, describes the Observatory implementation concept including the payload and spacecraft elements and summarizes the mission status.

IXPE - The Imaging X-Ray Polarimetry Explorer

Abstract: The Imaging X-ray Polarimetry Explorer (IXPE) is a Small Explorer Mission that will be proposed in response to NASA's upcoming Announcement of Opportunity. IXPE will transform our understanding of the most energetic and exotic astrophysical objects, especially neutron stars and black holes, by measuring the linear polarization of astronomical objects as a function of energy, time and, where relevant, position. As the first dedicated polarimetry observatory IXPE will add a new dimension to the study of cosmic sources, enlarging the observational phase space and providing answers to fundamental questions. IXPE will feature x-ray optics fabricated at NASA/MSFC and gas pixel focal plane detectors provided by team members in Italy (INAF and INFN). This presentation will give an overview of the proposed IXPE mission, detailing the payload configuration, the expected sensitivity, and a typical observing program.

IXPE Observatory Integrated Thermal, Power, and Attitude Mission Design Analysis

Abstract: When the Imaging X-ray Polarimetry Explorer (IXPE) launches in 2021, the world will have a new orbiting Xray observatory capable of examining previously unexplored celestial phenomena. For the first time, an earth-orbiting observatory will be able to resolve the polarization angle of each incoming X-ray photon in an imaged scene, and provide polarization measurements of each source within the instrument's field of view. The two top-level project requirements that drive the mission design and observatory capability are the execution, in a one year period, of a Design Reference Mission (DRM) containing 48 representative targets, and the ability to observe any location on the celestial sphere for 30 days every six months. IXPE exceeds these driving requirements with a straightforward observatory design concept that allows a large instrument field of regard with a fixed solar array. IXPE completed its preliminary design review in June 2018 with a baseline power and thermal design that accommodates all observatory attitudes that maintain a +/- 25 degree angle between the body-fixed solar array and the plane normal to the sun vector. This paper examines how observatory attitude affects power consumption, how the DRM targets drive the observatory power and thermal design, and potential system design trades.

IXPE Observatory Verification and Validation Approach and Threads Tool

Abstract: The Imaging X-ray Polarimetry Explorer (IXPE) is a NASA Small Explorer X-ray astrophysics mission being implemented by a geographically dispersed team. The IXPE collaboration and Observatory complexity provide both unique challenges and advantages for Project V&V. A rigorous and iterative V&V process is essential to ensuring the successful realization of reliable and cost effective IXPE Mission System. The IXPE verification, validation and characterization (V&V) process starts at the component/unit level and rolls up to appropriate higher levels. V&V compliance is assured by collaborative development by the V&V Team which spans all project organizations. The V&V process provides a framework, with appropriate confidence, to show that all needs and expectations are met by the as-built system. Proof is in the form of traceable detailed evidence of compliance at every level rolling up to and including the overall system and architecture levels. The detailed verification approach for IXPE components/units/subassemblies/subsystems is the responsibility of the applicable subsystem RE supported by systems and the I&T team. All verification processes, analyses and steps are documented. IXPE is using a V&V threads process which is ideal for use in showing compliance when a requirements set is dependent on a complex set of actions/processes. It's a system engineering graphics method to ensure all ‘contributors’ and ‘influencers’ are included. When applicable, verification threads are provided to support the verification compliance/sell-off process. This paper summarizes the IXPE mission and describes the verification, validation and characterization activities planned for the IXPE mission including the use of V&V threads.

The Gas Pixel Detector as a solar X-ray polarimeter and imager

Abstract: Abstract The Sun is the nearest astrophysical source with a very intense emission in the X-ray band. The study of energetic events, such as solar flares, can help us to understand the behaviour of the magnetic field of our star. There are in the literature numerous studies published about polarization predictions, for a wide range of solar flares models involving the emission from thermal and/or non-thermal processes, but observations in the X-ray band have never been exhaustive. The gas pixel detector (GPD) was designed to achieve X-ray polarimetric measurements as well as X-ray images for far astrophysical sources. Here we present the possibility to employ this instrument for the observation of our Sun in the X-ray band.

IXPE Mission System and Development Status

Abstract: IXPE, an international collaboration, will conduct x-ray imaging polarimetry for multiple categories of cosmic x-ray sources such as neutron stars, stellar-mass black holes, supernova remnants and active galactic nuclei. The Observatory uses a single science operational mode capturing the x-ray data from the targets. This paper summarizes the IXPE Mission System: Observatory, Launch Segment and Ground System. 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 x-ray telescopes each consisting of a polarization-sensitive, gas pixel x-ray detector, paired with its corresponding grazing incidence mirror module assembly (MMA), x-ray optics set. 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-small spacecraft architecture. IXPE is launched to a circular LEO orbit at an altitude of 600 km and an inclination of -0.2 degrees by a Falcon 9 launch vehicle. The ground system consists of three major elements: the ground stations for data receipt and command upload to the Observatory; the Mission Operations Center (MOC) at University of Colorado Laboratory for Atmospheric and Space Physics (CU/LASP); and Science Operations Center (SOC) at NASA Marshall Space Flight Center (MSFC). This paper summarizes the IXPE mission science objectives, updates the Observatory implementation concept including the payload and spacecraft elements, covers the launch segment, ground system and summarizes the mission status since last year's conference including COVID impacts.