The final year of the Rosetta mission

Abstract

The International Rosetta Mission was launched on 2nd March 2004 on its 10 year journey to rendezvous with comet 67P Churyumov-Gerasimenko. Rosetta performed comet orbit insertion on the 6th of August 2014, after which it characterised the nucleus and orbited it at altitudes as low as a few kilometres. In November 2014 Rosetta delivered the lander Philae to perform the first soft landing ever on the surface of a comet. After this critical operation, Rosetta began the escort phase of the comet in its journey in the Solar System heading to the perihelion, reached in August 2015. Originally foreseen till the end of 2015, the mission was extended for another nine months to follow the comet on its outbound arc of the orbit. In view of the acquired experience and of the approaching end of mission the spacecraft was flown at much closer distances from the nucleus so that the scientific instruments had the chance to perform unique measurements. Following this phase of very close orbits, on the 30th of September 2016 Rosetta was set on a collision course trajectory with the comet to terminate the mission with a controlled impact.This paper describes the details of the extended mission phase and the issues encountered during these months. It also includes the changes implemented on the spacecraft and in the operations concept to optimise the remaining mission time. The paper also includes the lessons learned from this unique and complex mission phase.