EUROPEAN SPACE AGENCY
EUROPEAN SPACE OPERATIONS CENTRE
GROUND SYSTEMS ENGINEERING DEPARTMENT
Mission Analysis Office
CLASSIFICATION OF GEOSYNCHRONOUS OBJECTS
All geostationary or near-geostationary objects catalogued in ESA's DISCOS Database (Database and Information System Characterising Objects in Space) are listed in this document. An object is considered as geostationary or near-geostationary if it meets the following criteria:
They can be classified as follows:
Compared with the last issue of January 2004 the following changes can be observed: There were 23 new objects (18 payloads and 5 rocket bodies) launched into or near GEO during the last year.
13 spacecraft reached end of life as far as it can be inferred from the orbital elements stored in DISCOS (or declared by spacecraft operators): five were reorbited more than 300 km above GEO: Astra 1A (88109B), GSTAR 4 (90100B, US), Insat II R (92010B, India, previously Arabsat 1C), GOES 8 (94022A, US) and PAS 6 (97040A, US). Five spacecraft were reorbited into a graveyard orbit below the altitude recommended by IADC:
Comstar 4 (81018A, Tonga) and Zhongxing 6 (97021A, China) seemed to have been abandoned around the Eastern stable point last year. ACTS (93058B, US) was moved to 105° W already in August 2000 after it was realised that the propellant reserves revealed a much lower amount than expected. However, it was only decommisioned on 28 April 2004 (source: Orbital Debris Quaterly News, July 2004).
In 2004 five rocket upper stages were added to the GEO debris environment:
This analysis has shown that the IADC reorbiting recommendations were only partially followed by the spacecraft operators. A more rigorous control of the reorbiting practices in GEO is required to preserve this unique resource.
1. Samsom P., "Classification of Geostationary Objects", ESOC - MAS WP 420, 1999.
The authors thank Nicholas Johnson and Vladimir Agapov for their suggestions and valuable contributions.