APSIS: Automated Photometric Survey of Inactive Satellites

Researchers from the Astronomical Institute have recently published a new study presenting APSIS, an automated program for the long-term, high-precision photometric monitoring of inactive satellites in geosynchronous (GEO) and medium Earth orbits (MEO). Using the infrastructure at Berthelot Observatory, APSIS delivers a unique multi-year dataset of satellite lightcurves and astrometry, enabling systematic investigations of rotational dynamics and long-term orbital stability, key components of Space Situational Awareness (SSA).

The study demonstrates that APSIS can detect subtle, near-annual variations in satellite rotation periods, attributed to solar radiation pressure (SRP) torques, and constrain satellite spin-axis orientations through physics-based modeling. In addition, the authors introduce a novel lightcurve inversion framework that reconstructs satellite geometry from unresolved optical observations, providing new insight into the physical properties of derelict space assets. This work highlights the growing role of automated optical surveys in monitoring inactive satellites and improving the safety and sustainability of the near-Earth space environment.

The results have been published in the journal Acta Astronautica.