IMPACT OF SOLAR FLUX MODELING ON SATELLITE LIFETIME PREDICTIONS

摘要

The number of objects in low Earth orbits (LEO) is increasing. Especially in the densely populated region of theSun-synchronous orbits near 800 km, the so called Kessler syndrome will lead to a further increase of objects dueto mutual collisions. In order to counteract this effect, several measures are recommended by the Space DebrisMitigation Guidelines of the UN Committee on the Peaceful Uses of Outer Space (UNCOPUOS). One of theseguidelines states that the long-term presence of spacecraft in LEO should be limited after the end of the mission.If the direct de-orbit, followed by a controlled re-entry of the spacecraft, is not possible, the spacecraft should betransferred to an end-of-life (EOL) orbit with a limited residual lifetime. The IADC recommends the residual lifetimeof the spacecraft on its EOL orbit not to exceed a maximum of 25 years.In order to define the residual lifetime of a spacecraft on a certain orbit, a propagation has to be performed,considering all major perturbations. The orbital decay is mainly driven by atmospheric perturbations, affecting theorbit's eccentricity and semi-major axis and thus the orbital altitude. The magnitude of the residual drag of theatmosphere depends on many parameters, for example the spacecraft mass, geometry, the composition of the upperatmosphere, etc.In this paper the influence of different modeling approaches for the future solar flux estimation with respect to theorbital decay shall be investigated. Within the new version of ESA's Debris Mitigation Analysis Tool DRAMA, thisoption is included as an input for the Orbital Spacecraft Active Removal (OSCAR) tool. The future solar flux indexvalue may, for example, be assumed to be at a constant level, which is also stated by the ECSS standard (ECSS-EST-10-04C). However, it is also possible to model the future solar flux as a replication of an exemplary past solarcycle. Another possible method is to derive a best-guess estimation based on currently available measurement dataof the solar flux. Different example spacecraft shall be analysed with respect to their residual lifetime, comparing thedifferent approaches in future solar flux modeling.