On-orbit risk reduction — collision avoidance

Abstract

Since more than 10 years, the European Space Operations Centre has been monitoring close proximities of objects of the US Space Surveillance Network catalogue with operational European Space Agency (ESA) satellites in low-Earth orbits. In recent years, this activity has evolved into an operational service that is provided for the ERS-2 and Envisat remote sensing satellites. In the current article, the basic principles of ESA's catalogue-based conjunction event detection and collision risk estimation process are explained, associated orbit prediction uncertainties are addressed, operational collision avoidance procedures are outlined, avoidance manoeuvre criteria are explained, and examples of evasive manoeuvres are provided. The observed manoeuvre rate is compared with a statistical manoeuvre frequency assessment, based on collision flux predictions for catalogue-size objects by ESA's MASTER-2001 space debris environment model.