​​On the effect of Apophis on Earth-orbiting satellites​

Abstract

​​While most planetary defence efforts focus on impact prevention, even a non-collisional encounter has the potential to perturb satellite, with consequences for communications, navigation and space safety. However, little attention has been given to the effect of close asteroid approaches on Earth-orbiting satellites. The 2029 flyby of asteroid Apophis (99942), which will pass closer than the geostationary belt, offers a unique opportunity to study this overlooked aspect of planetary defence. This thesis develops a framework to estimate the perturbations induced by asteroid flybys on satellites. A numerical propagator was implemented in Python to simulate the Sun Earth-Moon-Asteroid system, including major gravitational perturbations, Earth’s oblate ness and triaxiality, Solar Radiation Pressure and Apophis’s influence. The methodology was first applied to geostationary satellites, given the proximity of Apophis’s trajectory. Six representative GEO spacecraft and debris objects were ana lysed. Results indicate that perturbations remain very limited, producing longitudinal ground-track drifts of a few metres over several months, while Keplerian elements such as semimajor axis, eccentricity, inclination and RAAN remain essentially unchanged. The study was then extended to tailored artificial orbital configurations dynamically close to Apophis during the encounter. In these extreme cases, perturbations reached 30–37 metres in longitude and induced permanent but small shifts in semimajor axis ( 1 m) and eccentricity ( 10e−8). Finally, a search for real satellites near these sensitive regions identified objects such as PROBA-3 CSC (62256) and PSLV R/B (62257). These showed much larger perturations, with kilometre-scale changes in semimajor axis and hundreds of kilometres in ground-track displacement. In conclusion, while Apophis’s 2029 encounter will not cause catastrophic disruptions, it can significantly affect certain Earth-orbiting satellites. This study demonstrates that asteroid-induced perturbations are a genuine hazard for space operations and provides a novel framework to assess their impact, complementing impact-focused planetary defence strategies with the evaluation of orbital stability risks.​