A watchful eye on the sky: monitoring the mess of near-Earth space

 

In the six decades following the launch of Sputnik 1, thousands of satellites have been placed into orbit around the Earth. It has become increasingly clear that this number is now dwarfed by a population of artificial debris originating from launch hardware, break-ups and long-term deterioration. This talk will provide an overview of efforts underway at the University of Warwick (UK) to detect, monitor and characterize these objects.

 

We have repurposed the former exoplanet-finder, SuperWASP-North, to monitor objects in the spatially-dense low Earth orbit (LEO) region. Its super-wide field of view allows for the extraction of high-precision light curves as the targets streak across the resulting image frames. For the higher-altitude geosynchronous (GEO) regime, we exploit the faster readout of a 14'' robotic astrograph to achieve a similar goal. With these instruments, we aim to assemble a new database of LEO and GEO light curves that can support future projects on machine learning classification and object modelling.

 

Recent anomalies exhibited by the GEO satellites Intelsat 29e, AMC-9 and Telkom 1 have highlighted the existence of a relatively unknown population of faint debris at GEO altitudes. We use the 2.54 m Isaac Newton Telescope on the Canary Island of La Palma to probe down to 21st V Magnitude, corresponding to a size of roughly 10 cm, assuming Lambertian spheres with an albedo of 0.1. Interestingly, we find several objects that are rapidly tumbling in and out of our detection limit over the course of a single exposure. These pose a rather complex issue due to the difficulty in obtaining an estimate of object size with such variation in brightness.