GIOTTO — In-Flight Thermal Performance

On July 2nd, 1985 the Giotto spacecraft was launched from Kourou (French Guyana) towards its encounter with Halley’s comet on 13-14 March 1986.

This first European Space Agency interplanetary spacecraft was spin stabilized and weighed 960 kg at launch. Giotto was injected into a heliocentric orbit involving variations of the solar intensity by a factor of two. This fact together with the communications requirements and comet encounter geometry restricted the spacecraft attitude such that during the 9 month mission all external surfaces were illuminated by the sun, imposing severe limitations on the use of any surface for efficient heat rejection.

The spacecraft thermal control subsystem included several heater circuits and three “thermal shutters” operated by ground command. The daily configuration of these items was balanced between thermal and power requirements.

This paper presents an outline of the design characteristics of the spacecraft, its thermal control capabilities and a detailed summary of the flight performance.