CHARACTERIZATION OF LOW EARTH ORBIT DYNAMICS BY PERTURBATION FREQUENCY ANALYSIS

As part of the deep dynamical analysis carried out within the H2020 ReDSHIFT project, we present a charac- terization of the orbital elements of low-altitude objects in terms of their periodic components. Considering a representative sample of possible initial orbital conditions in the Low Earth Orbit (LEO) region, we propagated the dynamics of the objects over a suitable time span. The dynamical model includes the eects of geopotential up to degree and order 5, solar radiation pressure (SRP) and atmospheric drag. Lunisolar perturbations have been expressly removed from the model in order to account specically for the role of geopotential and SRP. Moreover, we considered two dierent values of the area-to-mass ratio of the object. Then, we decomposed the resulting quasi-periodic series in their spectral components by a numerical computation of Fourier transform, accounting for the nite duration of the signals. The aim of this spectral analysis is to clearly link each fre- quency signature to the dynamical eect which originates it in order to build a frequency chart of the LEO region. Indeed, the detailed analysis of the principal spectral components turns out to be a powerful tool to enable a better understanding of the relative importance of each specic gravititational and non-gravitational perturbation in the LEO region as a function of the initial semi-major axis, eccentricity and inclination of the object. Ultimately, the analysis will be used, together with the cartography of the LEO phase space, to identify the most suitable perturbations to be exploited to facilitate the passive dynamical de-orbiting of spacecraft at the end-of-life.