The 1997.0 CNUCE orbital debris reference model

A new orbital debris environment model (CODRM-97) has been developed. It includes the objects with mass greater than or equal to 1 mg produced by 140 energetic breakups, 16 liquid metal coolant leaks from nuclear powered spacecraft, international launch activity and space operations. Each fragmentation or leakage was simulated with the most appropriate models and parameters, and the resulting debris clouds were propagated, including all the significant orbital perturbations, to the chosen reference epoch (January 1, 1997). At this point, the particles still in orbit were merged with the catalogued objects present in space at the same time. In total, more than 65 millions of particles with mass greater than or equal to 1 mg were generated during the simulations and more than 52 millions resulted still in orbit at the reference epoch. Preliminary comparisons with the measurements available below 1000 km seem to indicate that the CODRM-97 predictions come short by a factor 2-3 for centimeter sized debris and by an order of magnitude for particles with diameters close to 1 mm. This deficiency might reflect, in part, an intrinsic inadequacy of the breakup models adopted, but probably suggests the presence in space of additional debris sources, not yet included in CODRM-97.