Description
Colour light curves of resident space objects (RSOs) encapsulate distinctive features that can offer insights into an object's structure and design, making them an invaluable tool for classification and characterisation. We undertook the first large systematic colour survey of the GEO belt with the STING instrument in which we obtained full-night multi-colour light curves for 112 active geostationary objects between April and May 2023. Characterisation was explored in the form of 2D colour light curve maps from which to compare and contrast the colours between different satellites and bus configurations. We found that satellites with certain buses can be effectively distinguished from the colour measurements on these maps, but comparing the average colour of individual satellites within given solar equatorial phase angle ranges shows that it is difficult to distinguish between bus configurations based on colour alone. We also found tentative evidence to suggest that there could be a relationship between colour and time spent on orbit for the Eurostar-3000 class satellites, which could point toward manufacturing changes. Common light curve features which were `bluer' such as unique regions of short timescale glinting and near symmetrical features were investigated. If these features are indeed seasonal, this would be a powerful characterisation tool.
