The cut-off date for events was June 30, 1998. This is the 1 st edition compiled and published by the Orbital Debris Program Office at the NASA JSC, with support from Lockheed Martin Space Mission Systems and Services. This document, often used by orbital debris modelers as a database and reference, now contains- information on 152 known breakups and 33 anomalous events. Earth satellite population of 8575 objects. Moreover, the sources of 9 of these 10 fragmentations were discarded rocket bodies which had operated as designed but later broke-up.
Rocket bodies are the primary sources for debris in orbit today.
This and other information can be found in the new edition which is now available to the orbital debris community. The current authors would also like to thank the authors of the previous editions of this document for making their input data available. In addition, the assistance of personnel of U.S. Space Command, Air Force Space Command, Naval Space Command, and Teledyne Brown Engineering has been vital to the present work. Risk objects were defined as man-made vehicles with a mass in excess of five metric tons or which contain hazardous materials. The reentry of such objects is rare, e.g., the US Skylab space station in 1979 and the Soviet Salyut 7-Kosmos 1686 space station in 1991, but the possibility of debris surviving reentry warrants special international attention.