Skimming through Saturn's Atmosphere: The Climax of the Cassini Grand Finale Mission

On September 15, 2017, the long-lived Cassini Mission to Saturn came to a triumphant end as the Cassini orbiter plunged deep into Saturn’s atmosphere, all the while transmitting engineering and science data back to Earth before Saturn’s atmosphere destroyed the orbiter. Even before the final plunge, the Cassini spacecraft became the first spacecraft to successfully skim Saturn’s atmosphere and collect atmospheric data during its final five complete orbits around Saturn (Rev-288 through Rev-292). During those five final orbits, the spacecraft was flying in Reaction Control Subsystem (RCS) control in order to maintain greater control authority. Therefore, by analyzing the thruster on-time flight data telemetered back to Earth after each orbit, atmospheric density estimates can be extracted. This paper proposes a method of using Cassini Attitude Control Flight Data to reconstruct Saturn atmospheric density profiles for each of the five final orbits around Saturn.