Orbital evolution of the first upper stages used for the new European and Chinese navigation satellite systems in MEO
- Paper number
IAC-10,A6,2,14,x6281
- Author
Dr. Luciano Anselmo, ISTI-CNR, Italy
- Coauthor
Dr. Carmen Pardini, ISTI-CNR, Italy
- Year
2010
- Abstract
During the last decade, since the discovery of the potential instability of the disposal orbits for the satellites of the global navigation systems (GNSS) in MEO, a considerable effort has been devoted in analyzing the initial conditions leading to instability, manifesting itself as a significant growth in eccentricity over a few decades, due to resonance conditions from the combined gravitational action of geopotential harmonics, Moon and Sun. Following these studies, solutions were proposed in order to delay, as much as practically possible, the penetration of the altitude shells populated by the operational spacecraft of the GNSS constellations. Because the eccentricity growth depends on the initial elements of the disposal orbit, the solutions discussed focused on the minimization of the disposal orbit initial eccentricity and the proper choice of the initial argument of perigee, not too expensive from the point of view of end-of-life propellant consumption. The aim of this paper is to analyze the solutions adopted for the disposal of the upper stages used to put in orbit the first new European (Galileo) and Chinese (Compass) navigation satellites in MEO. Their orbit evolution was modeled for 200 years, taking into account all relevant perturbations, and the chosen disposal options were compared with the current practices applied to GPS (USA) and Glonass (Russia). The results obtained were also discussed in the context of the instability problem analyzed in previous studies. It was found that the disposal orbits chosen for the two Fregat upper stages used to put in orbit the Galileo precursors and for the CZ-3A upper stage used for the first Compass spacecraft will actually reduce to a minimum their interference with the operational constellations. The CZ-3A rocket body, left in an elliptical orbit with very low perigee, will be fully compliant with the IADC mitigation guideline for the presence in LEO (“25-year rule”), with a post-mission lifetime of about 10 years. Moreover, the decreasing apogee will rapidly cross the GPS and Glonass operational altitudes in just a few months. Concerning the two Fregat upper stages, the simulations have shown that, in the coming 200 years, the perigee heights will always remain more than 168 km above the Galileo operational altitude, never crossing one of the existing or planned constellations. Both the solutions adopted for the disposal of these first upper stages were, therefore, appropriate for the long term preservation of the MEO orbital shells used by the GNSS spacecraft.
- Abstract document
- Manuscript document
(absent)