The New Mission of ‘Rosetta’ Comet Chaser and In-Orbit First Temperature Results

The Rosetta spacecraft was re-targeted to a newly selected comet following a one-year launch delay. The thermal control of the spacecraft has to cope with a large Sun distance range - 0.88 to 5.35 AU - and increasing comet activity combined with operational conditions that span from full payload activity to power saving hibernation mode. The new mission stretches the range of solar flux even further than the original mission and some adaptations to the thermal hardware were required. This paper describes how the new demanding mission scenario influenced the thermal design of the spacecraft and its operations. Then, the thermal behaviour of the spacecraft as revealed by the first in-orbit results is evaluated and compared where possible with the response anticipated by the analyses and by the environmental thermal test programme results. Rosetta was injected into an Earth escape trajectory on March 2^th 2004 by an Ariane 5 dedicated launch.