Design and Validation of a Technology Demonstrator for an Autonomous Orbit Determination System for Small Satellite Constellation

Design and Validation of a Technology Demonstrator for an Autonomous Orbit Determination System for Small Satellite Constellation This thesis work is inserted within the context of a project for a deep??space autonomous navigation system proposed by Argotec, an Italian aerospace engineering company based in Turin. The mission considered is "Autonomous oRbit dEtermination System for Smallsats Constella??tion (ARES4SC)" which aims at developing a constellation of five small satellites capable of determining their precise ephemerides after being deployed around a planet. Son of Zeus and Hera, Ares is the Greek god of war and from its Roman counterpart, Mars, the ARES4SC mission took the reference planet, with the concept being however suitable for any other celestial body. In this scenario this thesis presents the studies and the development steps conducted in order to design and digitally implement on a Software Defined Radio a suitable Inter Satellite Link (ISL) signal capable of extracting the radiometric observables needed for the satellites of the constellation in order to derive a valid orbital solution. Multiple ISLs share simultaneously the same frequency portion in a CDMA scheme adopting deterministic yet random-like spreading sequences that both reduce the Multiple Access Interference and allow a two-way ranging between satellites. Other core architectural element of the constellation is a single Ultra Stable Oscillator to be placed in one satellite only. The stability of such frequency source has to be characterized and the possibility to adopt a commercial (hence cheaper but presumably less accurate) oscillator has to be verified by proving its noise suppression when dealing with short distances between satellites.