Flight Operations and Lessons Learned of the Rosetta Alice Ultraviolet Spectrograph

This paper explores the uniqueness of ESA Rosetta mission operations from the Alice ultraviolet spectrograph instrument point of view, documents lessons learned, and suggests operations ideas for future missions. The Alice instrument mounted on the Rosetta orbiter is an imaging spectrograph optimized for cometary far-ultraviolet spectroscopy with the scientific objectives of measuring properties of the escaping gas and dust, as well as studying the surface properties, including searching for exposed ices. Described within this paper are the operations processes during the comet encounter period (2014-2016), the many interfaces to contend with, the constraints that impacted Alice, and how the Alice science goals of measuring the cometary gas characteristics and their evolution were achieved. Details are provided that are relevant to the use and interpretation of Alice data and published results. All these flight experiences and lessons learned will be useful for future cometary missions that include ultraviolet spectrographs in particular, as well as multi-instrument international payloads in general.