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: o eccentricity smaller than 0.1 o mean motion between 0.9 and 1.1 revolution per sideral day, corresponding approxi mately to a semi-major axis of 42164 ± 2800 km o inclination lower than 20 degrees 893 objects met these criteria as of 31 December 2005. 196 more objects are also known to be in this orbital region although no orbital elements are available in DISCOS. Thus, the total number of known objects in the geostationary region is 1089.
They can be classified as follows:
Additionally we have orbits for 103 unidentified objects. Some of those probably belong to objects where no recent TLEs are available but which are already included in the total number of 1089.
Compared with the last issue of January 2005 the following changes can be observed: There were 25 new objects (22 payloads, 2 rocket bodies and 1 piece of debris) launched into or near GEO during the last year.
18 spacecraft reached end of life as far as it can be inferred from the orbital elements stored in DISCOS or declared by spacecraft operators. 10 were reorbited more than 260 km above GEO complying with the IADC reorbiting guideline:
Three spacecraft were reorbited more than 200 km above GEO:
These spacecraft are right at the border of the 200 km protected zone around GEO. Long-term propagation of the orbit of Galaxy V has shown that it will not intrude into the 200 km protected zone (N. Johnson, pers. communication). Superbird A2 was injected after launch into a wrong orbit and after 7 months there was an anomaly caused by decrease in the fuel tank pressure. Therefore, the reorbiting could not be performed as originally foreseen.
Three spacecraft were reorbited into a graveyard orbit clearly below the altitude recommended by IADC:
UFO 3 (94035A) and Intelsat 804 (97083A) suffered catastrophic failures and have started librating now around one or even both libration points.
In 2005 two Russian Proton-K fourth stages were added to the GEO debris environment: 05010F was left in a libration orbit around the Eastern libration point and 05023H was left 100 x 200 below GEO.
This analysis has shown that in 2005 the IADC reorbiting recommendations were much better followed by the spacecraft operators than in previous years. Only three Asian spacecraft were clearly not following the IADC guidelines. It has to be noted though that no Russian and Chinese GEO spacecraft was retired in 2005.
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. They also thank Fernand Alby, Daniel Navarro, Akira Kato, Stephan Anstotz and Anders Soerensen for providing background information on individual satellites and covers, and James Dick for editorial comments.