ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis):
Two sensors will determine the composition of the comet’s atmosphere and ionosphere, the velocities of electrified gas particles, and reactions in which they take part. It will also investigate possible asteroid outgassing.
The Orbiter's scientific payload includes 11 experiments, in addition to the Lander. Scientific consortia from institutes across Europe and the United States have provided these state-of-the-art instruments. All of them are located on the side of the spacecraft that will permanently face the comet during the main scientific phase of the mission.