Enhancement of Trajectory Determination of Orbiter Spacecraft by Using Pairs of Planetary Optical Images

The subject of the present thesis is about the enhancement of orbiter spacecraft navigation capabilities obtained by the standard radiometric link, taking advantage of an imaging payload and making use of a novel definition of optical measurements. An ESA Mission to Mercury called BepiColombo, was selected as a reference case for this study, and in particular its Mercury Planetary Orbiter (MPO), because of the presence of SIMBIO-SYS, an instrument suite part of the MPO payload, capable of acquiring high resolution images of the surface of Mercury. The use of optical measurements for navigation, can provide complementary informations with respect to Doppler, for enhanced performances or a relaxation of the radio tracking requisites in term of ground station schedule. Classical optical techniques based on centroids, limbs or landmarks, were the base to a novel idea for optical navigation, inspired by concepts of stereoscopic vision. In brief, the relation between two overlapped images acquired by a nadir pointed orbiter spacecraft at different times, was defined, and this information was then formulated into an optical measurement, to be processed by a navigation filter. The formulation of this novel optical observable is presented, moreover the analysis of the possible impact on the mission budget and images scheduling is addressed. Simulations are conducted using an orbit determination software already in use for spacecraft navigation in which the proposed optical measurements were implemented and the final results are given

A simulation framework to assess pattern matching algorithms in a space mission

none2Within the framework of the European Space Agency (ESA), the BepiColombo space mission will target Mercury as the planet to be studied to discover more about the formation and the composition of the inner planets of our solar system. Mercury exhibits an effect (the libration) whose amplitude could determine whether the core is liquid. The method we propose to estimate the libration amplitude is based on matching of surface features extracted from image pairs taken at different epochs and thereby affected by illumination and scale artifacts. Since no detailed image pairs are available to assess the accuracy of the methods we propose, in order to generate synthetic images of the planet’s surface we have developed the simulation framework we present in this work. Finally, we discuss some preliminary matching results on surface features extracted from our synthetic images taken at different altitude and affected by illumination changes.noneA. Gherardi; A. BevilacquaA. Gherardi; A. Bevilacqu