Science goals and new mission concepts for future exploration of Titan’s atmosphere, geology and habitability: titan POlar scout/orbitEr and in situ lake lander and DrONe explorer (POSEIDON)
Authors: Rodriguez Sébastien , Vinatier Sandrine , Cordier Daniel , Tobie Gabriel , Achterberg Richard K. , Anderson Carrie M. , Badman Sarah V. , Barnes Jason W. , Barth Erika L. , Bézard Bruno , Carrasco Nathalie , Charnay Benjamin , Clark Roger N. , Coll Patrice , Cornet Thomas , Coustenis Athena , Couturier-Tamburelli Isabelle , Dobrijevic Michel , Flasar F. Michael , de Kok Remco , Freissinet Caroline , Galand Marina , Gautier Thomas , Geppert Wolf D. , Griffith Caitlin A. , Gudipati Murthy S. , Hadid Lina Z. , Hayes Alexander G. , Hendrix Amanda R. , Jaumann Ralf , Jennings Donald E. , Jolly Antoine , Kalousova Klara , Koskinen Tommi T. , Lavvas Panayotis , Lebonnois Sébastien , Lebreton Jean-Pierre , Le Gall Alice , Lellouch Emmanuel , Le Mouélic Stéphane , Lopes Rosaly M. C. , Lora Juan M. , Lorenz Ralph D. , Lucas Antoine , MacKenzie Shannon , Malaska Michael J. , Mandt Kathleen , Mastrogiuseppe Marco , Newman Claire E. , Nixon Conor A. , Radebaugh Jani , Rafkin Scot C. , Rannou Pascal , Sciamma-O’Brien Ella M. , Soderblom Jason M. , Solomonidou Anezina , Sotin Christophe , Stephan Katrin , Strobel Darrell , Szopa Cyril , Teanby Nicholas A. , Turtle Elizabeth P. , Vuitton Véronique , West Robert A. 
Published: January 2022

In response to ESA’s “Voyage 2050” announcement of opportunity, we propose an ambitious L-class mission to explore one of the most exciting bodies in the Solar System, Saturn’s largest moon Titan. Titan, a “world with two oceans”, is an organic-rich body with interior-surface-atmosphere interactions that are comparable in complexity to the Earth. Titan is also one of the few places in the Solar System with habitability potential. Titan’s remarkable nature was only partly revealed by the Cassini-Huygens mission and still holds mysteries requiring a complete exploration using a variety of vehicles and instruments. The proposed mission concept POSEIDON (Titan POlar Scout/orbitEr and In situ lake lander DrONe explorer) would perform joint orbital and in situ investigations of Titan. It is designed to build on and exceed the scope and scientific/technological accomplishments of Cassini-Huygens, exploring Titan in ways that were not previously possible, in particular through full close-up and in situ coverage over long periods of time. In the proposed mission architecture, POSEIDON consists of two major elements: a spacecraft with a large set of instruments that would orbit Titan, preferably in a low-eccentricity polar orbit, and a suite of in situ investigation components, i.e. a lake lander, a “heavy” drone (possibly amphibious) and/or a fleet of mini-drones, dedicated to the exploration of the polar regions. The ideal arrival time at Titan would be slightly before the next northern Spring equinox (2039), as equinoxes are the most active periods to monitor still largely unknown atmospheric and surface seasonal changes. The exploration of Titan’s northern latitudes with an orbiter and in situ element(s) would be highly complementary in terms of timing (with possible mission timing overlap), locations, and science goals with the upcoming NASA New Frontiers Dragonfly mission that will provide in situ exploration of Titan’s equatorial regions, in the mid-2030s.