Review of X-ray pulsar spacecraft autonomous navigation

This article provides a review on X-ray pulsar-based navigation (XNAV). The review starts with the basic concept of XNAV, and briefly introduces the past, present and future projects concerning XNAV. This paper focuses on the advances of the key techniques supporting XNAV, including the navigation pulsar database, the X-ray detection system, and the pulse time of arrival estimation. Moreover, the methods to improve the estimation performance of XNAV are reviewed. Finally, some remarks on the future development of XNAV are provided.Comment: has been accepted by Chinese Journal of Aeronautic

The Neutron star Interior Composition Explorer (NICER): design and development

During 2014 and 2015, NASA's Neutron star Interior Composition Explorer (NICER) mission proceeded successfully through Phase C, Design and Development. An X-ray (0.2-12 keV) astrophysics payload destined for the International Space Station, NICER is manifested for launch in early 2017 on the Commercial Resupply Services SpaceX-11 flight. Its scientific objectives are to investigate the internal structure, dynamics, and energetics of neutron stars, the densest objects in the universe. During Phase C, flight components including optics, detectors, the optical bench, pointing actuators, electronics, and others were subjected to environmental testing and integrated to form the flight payload. A custom-built facility was used to co-align and integrate the X-ray "concentrator" optics and silicon-drift detectors. Ground calibration provided robust performance measures of the optical (at NASA's Goddard Space Flight Center) and detector (at the Massachusetts Institute of Technology) subsystems, while comprehensive functional tests prior to payload-level environmental testing met all instrument performance requirements. We describe here the implementation of NICER's major subsystems, summarize their performance and calibration, and outline the component-level testing that was successfully applied

NASA Tech Briefs, Februrary 2013

Topics covered include: Measurements of Ultra-Stable Oscillator (USO) Allan Deviations in Space; Gaseous Nitrogen Orifice Mass Flow Calculator; Validation of Proposed Metrics for Two-Body Abrasion Scratch Test Analysis Standards; Rover Low Gain Antenna Qualification for Deep Space Thermal Environments; Automated, Ultra-Sterile Solid Sample Handling and Analysis on a Chip; Measuring and Estimating Normalized Contrast in Infrared Flash Thermography; Spectrally and Radiometrically Stable, Wideband, Onboard Calibration Source; High-Reliability Waveguide Vacuum/Pressure Window; Methods of Fabricating Scintillators With Radioisotopes for Beta Battery Applications; Magnetic Shield for Adiabatic Demagnetization Refrigerators (ADR); CMOS-Compatible SOI MESFETS for Radiation-Hardened DC-to-DC Converters; Silicon Heat Pipe Array; Adaptive Phase Delay Generator; High-Temperature, Lightweight, Self-Healing Ceramic Composites for Aircraft Engine Applications; Treatment to Control Adhesion of Silicone-Based Elastomers; High-Temperature Adhesives for Thermally Stable Aero-Assist Technologies; Rockballer Sample Acquisition Tool; Rock Gripper for Sampling, Mobility, Anchoring, and Manipulation; Advanced Magnetic Materials Methods and Numerical Models for Fluidization in Microgravity and Hypogravity; Data Transfer for Multiple Sensor Networks Over a Broad Temperature Range; Using Combustion Synthesis to Reinforce Berms and Other Regolith Structures; Visible-Infrared Hyperspectral Image Projector; Three-Axis Attitude Estimation With a High-Bandwidth Angular Rate Sensor Change_Detection.m; AGATE: Adversarial Game Analysis for Tactical Evaluation; Ionospheric Simulation System for Satellite Observations and Global Assimilative; Modeling Experiments (ISOGAME); An Extensible, User- Modifiable Framework for Planning Activities; Mission Operations Center (MOC) - Precipitation Processing System (PPS) Interface Software System (MPISS); Automated 3D Damaged Cavity Model Builder for Lower Surface Acreage Tile on Orbiter; Mixed Linear/Square-Root Encoded Single-Slope Ramp Provides Low-Noise ADC with High Linearity for Focal Plane Arrays; RUSHMAPS: Real-Time Uploadable Spherical Harmonic Moment Analysis for Particle Spectrometers; Powered Descent Guidance with General Thrust-Pointing Constraints; X-Ray Detection and Processing Models for Spacecraft Navigation and Timing; and Extreme Ionizing-Radiation-Resistant Bacteriu

The Use Of Variable Celestial X-ray Sources For Spacecraft Navigation

Accurate control and guidance of spacecraft require continuous high performance three-dimensional navigation solutions. Celestial sources that produce fixed radiation have demonstrated benefits for determining location near Earth and vehicle attitude. Many interplanetary navigation solutions have also relied on Earth-based radio telescope observations and substantial ground processing. This dissertation investigates the use of variable celestial sources to compute an accurate navigation solution for autonomous spacecraft operation and presents new methodologies for determining time, attitude, position, and velocity. A catalogue of X-ray emitting variable sources has been compiled to identify those that exhibit characteristics conducive to navigation. Many of these sources emit periodic signals that are stable and predictable, and all are located at vast distances such that the signal visibility is available throughout the solar system and beyond. An important subset of these sources is pulsar stars. Pulsars are rapidly rotating neutron stars, which generate pulsed radiation throughout the electromagnetic spectrum with periods ranging from milliseconds to thousands of seconds. A detailed analysis of several X-ray pulsars is presented to quantify expected spacecraft range accuracy based upon the source properties, observation times, and X-ray photon detector parameters. High accuracy time transformation equations are developed, which include important general relativistic corrections. Using methods that compare measured and predicted pulse time of arrival within an inertial frame, approaches are presented to determine absolute and relative position, as well as corrections to estimated solutions. A recursive extended Kalman filter design is developed to incorporate the spacecraft dynamics and pulsar-based range measurements. Simulation results demonstrate that absolute position determination depends on the accuracy of the pulse phase measurements and initial solutions within several tens of kilometers are achievable. The delta-correction method can improve this position solution to within 100 m MRSE and velocity to within 10 mm/s RMS using observations of 500 s and a 1-m2 detector. Comparisons to recorded flight data obtained from Earth-orbiting X-ray astrophysics missions are also presented. Results indicate that the pulsed radiation from variable celestial X-ray sources presents a significant opportunity for developing a new class of navigation system for autonomous spacecraft operation