Mars Express Marsis phobos commanding architectures

Abstract

Science objectives for the MARSIS experiment was defined more than 15 years ago in the context of the objectives of the Mars Express mission and in the more general frame of the open issues in the study of Mars at that time. The primary objective for MARSIS, was to map the distribution of water, both liquid and solid, in the upper portions of the crust of Mars. Secondary objectives defined for the MARSIS experiment included subsurface geologic probing and surface characterization of Mars. In order to achieve these ambitious scientific goals it was necessary to design an instrument with high computational capabilities, also to cope with some limitation imposed by the mission characteristics, such as the limited data-rate provided by the spacecraft and the limited available data volume. For these reasons, the on-board software is characterized by an high grade of flexibility that allow the possibility to modify the signal processing in order to face unpredictable issues arising during the mission. This capability was very useful when, after several years of Mars observation, Phobos became a scientific objective for MARSIS.