CASSINI, BEPI-COLOMOBO AND LISA: A series of space missions to test general relativity and probe gravitational waves

Friday 03 Jun 2022 @ 10:00 a.m., Laby Theatre(+Zoom)
Prof. Jean-Pierre Barriot, The University of French Polynesia; Email: jean-pierre.barriot[at]


We will discuss in this seminar how radio links in deep space make it possible to test general relativity and to probe gravitational waves, with three examples: a/ The NASA/ESA Cassini mission to Saturn, active in space for almost 20 years (1997-2017), which was equipped with an extremely precise radio system, and provided data capable of constraining the post-Newtonian gamma parameter to an unprecedented level of 1 + (2.1 ± 2.3)×10−5, and also gave upper bounds on the amplitude of gravitational waves at low frequency passing through the solar system. b/ The ESA/JAXA BepiColombo mission, launched on October 20, 2018, which is carrying out a seven-year journey to the smallest and closest to the Sun terrestrial planet, Mercury. It is equipped with a state-of-the-art radio system inherited from Cassini, with the aim of improving the accuracy of gamma determination by at least a factor of 10. c/ The LISA (Laser Interferometer Space Antenna), which will be a set of three spacecraft flying in a triangular formation about 50 million kilometers from the Earth, whose launch is scheduled for 2034. It was recently approved for Phase A study by the European Space Agency after results from the successful precursor LISA-Pathfinder mission in 2016 proved the concept feasible.