Jason Boyd, Ball Aerospace; Tony Ly, Ball Aerospace; Ian Gravseth, Ball Aerospace
Keywords: GPS, Denial, Location, GEO
Abstract:
Space has already become a key component of the national defense structure for multiple countries, and this is expected to continue in the coming decades. Countries with a significant presence in space have an economic and military advantage, and space assets will become increasingly vulnerable to potential threats. Due to the reliance on GNSS by most space systems, GPS denial becomes an obvious approach to disrupt an adversary’s space-based capabilities. Additionally, future GPS upgrades may reduce sidelobes, potentially impacting the ability of GEO systems to utilize GPS signals. Therefore, development of alternative strategies for orbit determination without GPS is a crucial technology for the future of space domain awareness.
This paper will explore the techniques that can be used to determine a satellites position in GEO without relying on a GPS signal. In ground-based, air and in low-orbit platforms, imagers can locate objects overhead with known locations/orbital parameters and determine the platform’s relative position to those objects. However, at GEO, there are fewer known objects at higher orbits, thus reducing angular diversity in position measurements and drastically increasing dilution of precision. In this study, we explore the viability of observational techniques for orbit determination of self, which when used in combination, can determine position and attitude without GPS.
The primary technique is to calculate position based upon the number of known, observable objects using a network of other SDA satellites as a known constellation. If a satellite can image and find the relative position of other SDA GEO satellites and a communication link can provide the precise position knowledge each satellite, then the absolute position of all satellites could be determined. Secondarily, interleaving observations near the earth limb for known objects in MEO will increase the angular diversity of observations and is expected to improve position uncertainty.
The paper will explore the sensitivity to applicable variables to understand what drives positional uncertainty, and what trade-offs would be required to reduce the uncertainty. It also discusses alternate approaches and provides recommendations for architecture to adequately address the problem.
Date of Conference: September 19-22, 2023
Track: Space Domain Awareness