Frequency characterization of orbits in the LEO region

As part of the deep dynamical analysis carried out within the H2020 ReDSHIFT project, we present a characterization of the orbital elements of low-altitude objects interms of their periodic components. Considering a representative sample of possible initial orbital conditions in the Low Earth Orbit (LEO) region, we propagated thedynamics of the objects over a suitable time span. The dynamical model includes the effects of geopotential up to degree and order 5, solar radiation pressure (SRP) andatmospheric drag. Lunisolar perturbations were expressly removed from the model in order to account specifically for the role of geopotential and SRP. Moreover, weconsidered different values of the area-to-mass ratio of the object. Then, we decomposed the resulting quasi-periodic series in their spectral components by a numericalcomputation of Fourier transform, accounting for the finite duration of the signals. The aim of this spectral analysis is to clearly link each frequency signature to thedynamical effect 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 tobe a powerful tool to enable a better understanding of the relative importance of each specific gravititational and non-gravitational perturbation in the LEO region as afunction of the initial semi-major axis, eccentricity and inclination of the debris. Ultimately, the analysis will be used, together with the cartography of the LEO phasespace, to identify the most suitable perturbations to be exploited to facilitate the passive dynamical de-orbiting of spacecraft at the end of life.