Investigating the formation of small Solar System objects using stellar occultations by satellites: present, future and its use to update satellite orbits.

The history of the outer solar system is intrinsically related to the Giant Planets migration. A massive disk of material within a radius of 30 au was scattered during the planetary migration, creating different dynamic populations in the Transneptunian region. They were formed in a collisional environment when massive collisions allowed them to grow and form much smaller moons than the primary body. The dynamical group, known as the Cold Classicals, was formed in a sparse disk from 42 to about 47 au and did not suffer much from planet migration. Observations show that many of Cold Classical are binary, consistent with the streaming instability process. The stellar occultation technique, with a spatial resolution of a few kilometres, can be used to search for binaries where other techniques are unable to do so, and to characterize the known satellites of Trans-Neptunian Objects (TNO), constraining their formation scenarios. We review here the first stellar occultations by TNO's satellites (besides Charon), and discuss the methods used to detect these events. We also fit new orbital elements and system mass for Vanth (Orcus/1) and Weywot (Quaoar/1), finding reasonable solutions for pure Keplerian orbits. Finally, we discuss the prospects regarding the stellar occultations by TNO binaries and their implications for the study of the history of the Solar System.This article is part of the theme issue 'Major advances in planetary sciences thanks to stellar occultations'.