Sun-synchronous Spacecraft Compliance with International Space Debris Guidelines

Abstract

Due to ever increasing accessibility, recent years have seen a fast growing number of launches to space, especially to Sun-synchronous orbit. The spent rocket parts, payload fairings and eventually non-functioning payloads of these launches remain in orbit. It is well-established that this accumulation of space debris over time is quickly making this the most severe threat to future spaceflight operations. To address and mitigate this problem a set of internationally agreed guidelines were established including a maximum of 25-year remaining orbital lifetime in this region after end-of-life. This study evaluates if Sun-synchronous satellite operators adhere to this guideline.

To determine this compliance, the operational status of the satellites with orbital control capabilities is established using a maneuver detection algorithm. For satellites without the capability to maneuver a model is created based on mass and design lifetime to determine the duration of the operational phase. Using a semi-analytic propagation method the remaining orbital lifetimes is determined.

The results show an overall compliance of 59% with an increasing trend starting around 2014, before which compliance was 20 to 40 %, to approximately 95% in 2017 and 2018. A large difference is observed for different mass categories, where satellites with a mass lower than 10 kg have a compliance of 86.4% compared to approximately 35% for heavier satellites. Analysis shows that this is mainly due to the lower orbits the former satellites were launched in. No large differences are observed between satellites with or without orbital control capabilities. These results reveal that compliance with the guidelines has been poor in the past but is increasing in recent years. This is mostly a result of operators choosing an orbit with a low altitude to have sufficient natural
decay, and less of operators choosing to perform altitude lowering maneuvers at the end of operational phase to achieve compliance.