Long-term evolution of geosynchronous orbital debris with high area-to-mass ratios

The long-term evolution, over 54 years, of a sample of objects released in geostationary orbit with area-to-mass ratios (A/M) up to 50 m^2/kg was analyzed, taking into account geopotential harmonics (8 ¡Á 8), luni-solar perturbations, direct solar radiation pressure with eclipses and, when applicable, air drag. The results obtained indicated that objects with A/M up to 25 m^2/kg might explain the recently discovered debris population with mean motions of about one revolution per day and orbital eccentricities as high as 0.6. At so large area-to-mass ratios, the orbital evolution was mainly driven by solar radiation pressure. Even though the general behavior observed was the same in all studied cases, the details of the evolution depended on the initial conditions. The simulated objects with A/M ¡Ü 37 m^2/kg were characterized by an orbital lifetime > 54 years, while for A/M > 40-45 m^2/kg, the exact value again depending on the initial conditions, the lifetime dropped rapidly to a few months with increasing values of the area-to-mass ratio. A growth of A/M had as consequence a larger amplitude of the yearly oscillations that dominate the eccentricity evolution, in addition to a faster and wider orbit pole clockwise precession.