Randa Qashoa, York University; Regina Lee, York University; Ryan Clark, C-CORE
Keywords: SSA, Simulation, FAI, CASSIOPE, Attitude
Abstract:
A major component of Space Situational Awareness (SSA) is the ability to predict, track and identify Resident Space Objects (RSO) in orbit. High fidelity RSO simulators are a critical tool in developing RSO tracking and detecting algorithms to generate simulated star field images with accurate representation of RSOs. RSO characteristics such as position, velocity, etc. are calculated from Two-Line Element (TLE), Orbital Mean-Elements Message (OMM), or ephemeris data. Most RSO simulators used in today’s SSA studies (including one developed in our research team) lack pre-built attitude profiles of the host observer, which is needed to determine the sensor’s boresight, or pointing direction. In this study, we present improvements to the simulator to include a wider range of inputs for the attitude information. Specifically, by introducing a known pointing profile for the satellite we can make more accurate predictions of the RSO’s position and velocity.
In exploring the addition of a known pointing profile to the simulator in cases where attitude information is lacking, we additionally limit ourselves to low-resolution cameras, akin to the ones used in star trackers, although the simulator can support high-resolution image generation as well. We limit the study to low-resolution imagers because high resolution imagers typically have known attitude information. Images from Cascade, Smallsat and Ionospheric Polar Explorer’s (CASSIOPE’s) Fast Auroral Imager (FAI) sensor were chosen due to similar sensor parameters to star trackers and the availability of public ephemeris files that we can use to generate even more realistic simulations for comparison. With the ephemeris and attitude information it is possible to extract the exact boresight vector for the sensor for every timestamp being studied. The FAI is currently locked in an anti-sun pointing mode due to a recent issue with CASSIOPE’s reaction wheels making it an ideal candidate for this study. An anti-sun pointing mode was implemented within the simulator and simulated images from ephemeris files will be used as validation data.
The validation will be accomplished by simulating FAI images that were predicted using the anti-sun pointing mode with simulated images generated using true ephemeris files that contain attitude information. In comparing the images, we will look at specific targets temporal features. Some of the temporal features we will compare are the entry and exit times between both sets of images as well as the observation duration between both methods. By proving the ability to predict a certain, known, spacecraft orientation with the simulator, we can then further improve its prediction capabilities by adding more orientation modes.
Many satellites utilize specific orientation profiles to achieve their various mission goals. Such pointing modes include anti-sun, nadir, or inertial pointing. Most satellites have known pointing modes which they reside in most of the time. However, they do not have publicly available attitude information, which impacts our ability to simulate images of star fields and RSOs. Our proposed solution is to use the pointing modes to approximate the attitude of the spacecraft so we can generate more accurate simulated images in cases where we are limited by the insufficient amount of data.
Date of Conference: September 19-22, 2023
Track: Space Domain Awareness