SYNERGISTIC USE OF DEBRIS ENVIRONMENT MODELS FOR FLEXIBLE, VERY-LONG TERM PROJECTIONS

Long-term debris environment projections are of great importance for a ssessing the necessity and effectiveness of debris mitigation measures . Two types of models have been developed to predict these environment s. Environment evolution models like the EVOLVE code are using detaile d mission model data to input spacecraft, upper stages; and operationa l debris into specific orbits at specific times; debris from fragmenta tions are placed in orbits defined by the state vector of the fragment ing object(s) and the breakup model. The second type, typified by the CHAIN program, uses a particle-in-box model that bins the environment in size and altitude rather than following the orbit evolution of indi vidual debris fragments. A 3-Step approach using both the EVOLVE and C HAIN model in a synergistic way was used to increase the reliability o f long term environment projections. EVOLVE historical projections 195 7-1995 could be validated by comparison to measurements. The compariso n of 100 year projection runs of EVOLVE and CHAIN for different traffi c scenarios showed a good agreement. In this paper, for the first time , CHAIN projections up to 10,000 years, based on validated boundary co nditions derived by EVOLVE are presented, indicating clearly the need of early implementation of effective mitigation measures to prevent ex ponential population growth by collisional cascading effects. (C) 1998 Elsevier Science Ltd. All rights reserved.