Veronique M A Dehant¹, Sébastien Le Maistre¹, Marie Yseboodt¹, Rose-Marie Baland¹, Ozgur Karatekin¹, Marie-Julie Péters¹, Attilio Rivoldini¹, Tim Van Hoolst¹, Bart Van Hove¹, Alexander Kosov² and the LaRa team, (1)Royal Observatory of Belgium, Brussels, Belgium, (2)IKI Space Research Institute of the Russian Academy of Sciences, Moscow, Russia