Edwin G. W. Peters, UNSW Canberra Space; Melrose Brown, UNSW Canberra Space; Andrew Lambert, UNSW Canberra Space; Lauren Glina, UNSW Canberra Space; Timothy Bateman, UNSW Canberra Space; Ed Kruzins, UNSW Canberra Space; Rabbia Saleem, UNSW Canberra Space; Travis Bessell, Clearbox Systems; Tim Spitzer, Clearbox Systems; Tom Wang, Clearbox Systems; Kriti Tripathi, Clearbox Systems; Damian Huxtable, Clearbox Systems; Michael Soire, Clearbox Systems; Simon Zinsli, Clearbox Systems; Thomas Powles, Clearbox Systems; Isabella Federle, Clearbox Systems; Mark Aragon, Bluerydge; Adam Haskard, Bluerydge; Mark Thompson, Capricorn Space; Warren Nielsen, Capricorn Space; Russell Boyce, UNSW Canberra Space
Keywords: passive RF, Australia, optical space surveillance, mission system, orbit determination
Abstract:
The number of near-Earth resident space objects is set to grow by an order of magnitude by the end of the decade. Developing new space traffic management systems is critical to mitigate the risk of on-orbit collision from the rapidly growing population of spacecraft. Future space traffic management systems must contend with not only an increase in the number of objects in orbit but an increasingly dynamic space environment, where low-thrust electric propulsion systems combined with artificial intelligence-based spacecraft navigation systems result in levels of manoeuvrability that were not envisioned during the design of existing space traffic systems. The emergence of commercial space actors as the primary owner/operators of future satellite technology has driven the transition of space traffic management from a military responsibility to civilian realm. It is therefore critical that new space domain awareness sensors and mission systems are developed from the civilian and commercial sector to meet both the technical and business/use case challenges that the changing utilisation of the space domain requires.
Australia has embarked on a dedicated effort in recent years to rise to the global space domain awareness challenge, seeking to exploit our advantages in geography and dark/Radio Frequency (RF) quiet skies through several government initiatives. The work presented here shall outline and update progress on the research and development of a new integrated passive RF and optical space domain awareness sensor network solution under the Australian Government’s round 9 cooperative research centre project (CRC-P) “A sensor network for integrated Space Traffic Management for Australia”. The program represents a tight collaboration between industry and academic partners to stimulate improved levels of translation from academic research into the commercial sector.
The passive RF sensor network ‘SpaceAware’ will comprise RF sensor sites located in Canberra, South Australia and Western Australia. The system will seek to detect actively transmitting satellites in the VHF, UHF, S, X and Ku bands, using a combination of omnidirectional and directional antennas. While the frequency offset due to Doppler for a satellite can be measured using a single receiving antenna, multiple receivers that are either co-located or geographically dispersed, can estimate the angle of arrival and range using array processing and time and frequency difference of arrival methods. The combination of omnidirectional and directional antennas allows for simultaneous monitoring of the entire horizon, while allowing tracking of specific objects for more accurate measurements. The cost and power requirements are significantly reduced compared to active RF systems, allowing a cost-effective geographically dispersed roll-out. The passive RF systems rely on the objects of interest actively transmitting and their beam width within the field of view of the sensor network. Coupling the system with optical telescopes provides the opportunity to enhance the space domain awareness information available for any given object. The research conducted during the CRC-P program will exploit UNSW Canberra’s 36cm, 2-degree field of view ‘VIPER’ telescope to provide tracking and characterization data to complement the passive RF sensor network. Following development and commissioning of the respective RF and optical systems, work shall commence on research to explore how metric and characterisation data can be exchanged between the optical and RF systems to extend the knowledge of space objects beyond what either system could independently yield.
The paper presents details of the program development, sensor network architecture, and preliminary results for select satellites. Example observations of the UNSW Canberra Space ‘M2’ formation flying CubeSat mission in the optical and RF spectrum shall be compared with GPS data from the spacecraft covering rendezvous and close-proximity manoeuvres executed through a sequence of differential aerodynamic drag manoeuvres. The algorithms implemented for extracting range-rate data from the passive RF signals and the approaches applied to those data for orbit determination shall be discussed. Initial work seeking to include spacecraft spin stability characterisation data through photometric light curve data from the Falcon Telescope Network and variations in the recorded RF signal strength will be presented for the M2 spacecraft. The preliminary results shall highlight opportunities for characterisation data to detect changes in spacecraft state that can be exploited to improve orbit determination and manoeuvre detection algorithms.
Date of Conference: September 27-20, 2022
Track: SSA/SDA