This study aims at the design of microsatellite to test fundamental physics in the solar system. The main scientific objective of the proposed experiment is to determine at which level of accuracy we can observe possible deviation from general relativity. Our focus would be on one of the classical tests of general relativity: the measurement of the light-path deflection by a mass (the Sun). So far, a deviation has never been observed by previous experiments, confirming the validity of the general relativity. In 2002, Cassini exploited radiometric measurements during a superior solar conjunction to obtain the most accurate verification of general relativity, up to now. The BepiColombo and JUICE mission plan to carry out the same experiment with a state-of-the-art radio tracking system. The aforementioned missions perform this experiment as a secondary function with respect to the primary goal of the mission. For this reason, these L-class missions (> 500 M€) were not optimized to perform this experiment. We aim at designing a cost-effective space mission with the primary objective of measuring the light-path bending due to the Sun, and possibly perform other fundamental physics tests. These tests are very demanding in terms of spacecraft dynamical modelling. The main disturbances on this kind of radio science experiments are the modelization of non-gravitational accelerations and solar corona plasma noise on the radio-links. We aim at characterizing the main environmental disturbances on the spacecraft dynamics and propose different solutions in terms of mission design and technological advancements to further improve the experiment accuracy. We want to identify the key aspect of the design of a micro satellite (mass
This research unifies two strong elements of innovation one related to the scientific objectives of the proposed mission and the second to the engineering developments that they would require. The accurate estimation of the Eddington parameter could lead to the first observation of a deviation from general relativity prediction. It would be a breakthrough in the scientific community that would bring new enthusiasm on the study on alternative theories of gravity. This objective has been pursued in the last century without any success. Recent development on radio-tracking system used on flying mission have shown the possibility to improve the results that we got so far. In a recent paper I demonstrated that the PN @ 24 Mcps of the BepiColombo mission is able to reach accuracies at centimeter level. This level of accuracy could be sufficient to unveil a deviation from general relativity. However, the mission design was not dedicated to this measurement and this parameter cannot be constrained at a sufficiently accurate level. That is why we propose a simple dedicated mission to measure the Eddington parameter.
The development of a dedicated micro satellite to achieve this mission bring problem of miniaturization that must be faced carefully. The nowadays accurate transponders are thought for large space mission of several tons (and millions/billions) while we want to focus on a small-satellite in order to keep the cost inside the S-class mission budget and reduce the overall complexity of the system. This study has the goal of identifying in which areas we need to push a technological advancements. Further, we want to design the best trajectory to obtain the maximum scientific signal while reducing at maximum the environmental disturbances.