Sarah Caddy, The University of Melbourne; Stephen Catsamas, The University of Melbourne; Michele Trenti, The University of Melbourne; Miguel Ortiz del Castillo, The University of Melbourne; Airlie Chapman, The University of Melbourne; Robert Mearns, The University of Melbourne
Keywords: Infrared, Thermal, Imaging, Characterization, Geostationary
Abstract:
Understanding the health, status and intent of a geostationary satellite that is so far away it cannot be spatially resolved by traditional telescopes, is a challenging problem. One method of extracting intelligence of these satellites is to use space based thermal infrared imaging to infer information about power flows, thruster firings and onboard operations.
The University of Melbourne Space Laboratory is developing a sovereign thermal infrared imaging capability for Australia that will remotely monitor the health of assets in space. We take a comprehensive approach to addressing the problem, by developing 3 main capabilities. 1) Thermal modelling of satellites, 2) characterisation of satellites from remote observations and 3) developing the hardware required to launch a thermal infrared space telescope for this purpose.
Firstly, we motivate the need for thermal infrared imaging for space domain awareness by describing the principles, challenges and benefits of this technique to derive intelligence of distant satellites. Thermal infrared photometry is used by Astronomers to determine the temperature of astronomical objects, such as asteroids and cold stars like brown dwarfs. All objects in space radiate heat. This can be due to their own internal heat generation such as the burning of material in the core of a star, or in the case of a satellite, the use of onboard electronics or electric thrusters. It can also be passive heat radiation such as asteroids or space debris which are warmed by the Sun. No object can mask it’s entire thermal emission spectrum – and as a result, it is an excellent tracer of an objects status and location. When we observe the infrared light coming from a source sampled at different wavelengths, we are able to determine the temperature of an object.
We demonstrate the ability of thermal infrared photometry to infer intelligence of a satellite using real data from the Wide-Field Infrared Survey Explorer (WISE) space telescope. While WISE data has been used extensively in the literature for the detection of satellites and colour analysis, there have been no (published) attempts at determining the temperature of the satellites using these data. We compare these observation to ground truth telemetry of observed satellites to validate our approach.
Finally, we present a technology pathfinder called SpIRIT. SpIRIT is a satellite operated by the University of Melbourne carrying a space telescope that operates in X-Ray wavelengths. SpIRIT has been in orbit operating for over 600 days, and hosts a technology demonstration of an active electric cooling module. The development of cost effective, modularised cooling methods of small satellites is critical for the development of future infrared space telescope for space domain awareness.
Date of Conference: September 16-19, 2025
Track: Satellite Characterization