GN&C Sequencing for Orion Rendezvous, Proximity Operations, and Docking

As part of the Artemis program to return humans to the lunar surface, the National Aeronautics and Space Administration is planning to use the Orion Multi- Purpose Crew Vehicle to transport crew to a small orbital platform called Gate- way in cislunar space. To facilitate this activity, Orion is required to perform Rendezvous, Proximity Operations, and Docking (RPOD) with both the Gate- way and the launch vehicle upper stage. The Orion spacecraft uses sequencing in the form of Phases, Segments, Activities, and Modes (PSAM) to configure Guidance, Navigation, & Control (GN&C) software during each portion of the mission. Significant updates to Orion PSAM definitions are required for RPOD. This paper describes the process of defining these new sequencing elements, implementing them in prototype flight software, and testing them in an integrated simulation environment. First, requirements are specified to determine the nominal and off-nominal sequencing behavior necessary to complete the mission. These requirements also specify which software functions should be fully autonomous and which functions require manual interactions from crew or ground operators. Next, the RPOD concept of operations is defined with detailed events listed in a mission timeline. Third, a state machine diagram is developed to show all PSAM states, including all possible transitions between them. After this, the PSAM states and transitions are entered into a sequencing software emulator and parameter values and modes are defined for GN&C software elements. Finally, the PSAM architecture is tested within an integrated simulation environment by connecting it with prototypes of relevant GN&C flight software elements and with detailed vehicle models. After the sequencing design has been finalized and tested, it is implemented in flight software

A Framework for Scaling in Filtering and Linear Covariance Analysis

Scaling is used extensively for numerical optimization and trajectory optimization. Its use in the estimation community is almost nonexistent. This paper creates the framework for practical scaling in space navigation, in general, and linear covariance analysis, in particular

The SMILE Soft X-ray Imager (SXI) CCD design and development

SMILE, the Solar wind Magnetosphere Ionosphere Link Explorer, is a joint science mission between the European Space Agency and the Chinese Academy of Sciences. The spacecraft will be uniquely equipped to study the interaction between the Earth’s magnetosphere-ionosphere system and the solar wind on a global scale. SMILE’s instruments will explore this science through imaging of the solar wind charge exchange soft X-ray emission from the dayside magnetosheath, simultaneous imaging of the UV northern aurora and in-situ monitoring of the solar wind and magnetosheath plasma and magnetic field conditions. The Soft X-ray Imager (SXI) is the instrument being designed to observe X-ray photons emitted by the solar wind charge exchange process at photon energies between 200 eV and 2000 eV. X-rays will be collected using a focal plane array of two custom-designed CCDs, each consisting of 18 µm square pixels in a 4510 by 4510 array. SMILE will be placed in a highly elliptical polar orbit, passing in and out of the Earth’s radiation belts every 48 hours. Radiation damage accumulated in the CCDs during the mission’s nominal 3-year lifetime will degrade their performance (such as through decreases in charge transfer efficiency), negatively impacting the instrument’s ability to detect low energy X-rays incident on the regions of the CCD image area furthest from the detector outputs. The design of the SMILE-SXI CCDs is presented here, including features and operating methods for mitigating the effects of radiation damage and expected end of life CCD performance. Measurements with a PLATO device that has not been designed for soft X-ray signal levels indicate a temperature-dependent transfer efficiency performance varying between 5 × 10−5 and 9 × 10−4 at expected End of Life for 5.9 keV photons, giving an initial set of measurements from which to extrapolate the performance of the SXI CCDs

Theorizing Institutional Scandal and the Regulatory State

One by one, UK public institutions are being scandalised for corruption, immorality or incompetence and subjected to trial by media and criminal prosecution. The state?s historic response to public sector scandal ? denial and neutralisation ? has been replaced with acknowledgement and regulation in the form of the re-vamped public inquiry. Public institutions are being cut adrift and left to account in isolation for their scandalous failures. Yet the state?s attempts to distance itself from its scandalised institutions, while extending its regulatory control over them, are risky. Both the regulatory state and its public inquiries risk being consumed by the scandal they are trying to manage

On-orbit satellite inspection : navigation and [Delta]v analysis

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.In title on t.p., "[Delta]" appears as the upper-case Greek letter.Includes bibliographical references (p. 213-215).Since the late 1950's when the first man-made satellite was launched into space, there has been a keen interest to inspect these orbiting spacecraft. In the past, there have been employed a variety of inspection methods which primarily consisted of different ground observation facilities. Unfortunately, ground-based sensors are often limited to the weather conditions and the particular flight path of the satellite. To overcome these and other obstacles, the inspection sensors can be moved from the ground and placed on spacecraft in orbit dedicated for satellite inspections. Is it possible for a miniaturized satellite to perform these inspections while on orbit? In this thesis, a small inspection satellite concept is developed and then verified using a high-fidelity 6 degree-of-freedom simulation. A detailed angles-only navigation analysis and [delta]v performance analysis of three different inspection trajectories are performed. The results of this analysis show the feasibility of angles-only rendezvous navigation and the over-all inspection satellite concept while validating the implemented flight algorithms.by David C. Woffinden.S.M