<h2>AAS  96-115</h2><h2>A NEW AND DETAILED EVALUATION OF THE NUMBER AND MASSES OF OBJECTS IN EARTH ORBIT</h2><h4>P. Eichler, Lockheed Martin Engineering & Sciences; P. Anz-Meador, Viking Science & Technology, Inc.</h4><h2> Abstract </h2>The risk of collision with Orbital Debris is of rising concern for spacecraft design and operations. Basis for collision risk analysis is the assessment of the number of objects as a function of mass/size, altitude and inclination. Within the scope of a major update of the historical launch data set at NASA/JSC several weaknesses (completeness of the data, obsolete masses etc.) could be identified and corrected. In this paper, detailed analysis is presented on the characteristics of the launched objects as well as the orbiting population of 1.1.1995, as their number and masses broken down in country of origin, launcher type used, and orbit type (LEO, MEO, GTO, MOLNIYA, GEO).<br><br>