Giotto—The mission operations system

Abstract

On 2 July 1985, the European Space Agency (ESA) launched an interplanetary probe to encounter Halley's Comet on the night of 13/14 March 1986 at a distance of 0.98 AU from Earth. The mission to Halley's Comet was the Agency's first venture into deep space. The tracking stations necessary to support such a mission were not directly available to ESA at the initiation of the GIOTTO project although facilities operated by NASA's deep space network were later made available for certain phases of the mission, together with the 30-m Weilheim antenna of the DFVLR. ESA's European Space Operations Centre, ESOC therefore developed the new deep space tracking stations especially for support of the GIOTTO mission. One of these stations, the 15-m antenna facility at Carnarvon, West Australia, was designed and installed by ESA as a dedicated S-band and X-band tracking, telemetry and command station. The second station at Parkes, New South Wales, Australia, a 64-m radio telescope owned by the Commonwealth Scientific and Industrial Research Organization (CSIRO) was modified to provide X-band telemetry reception using cryogenic MASER low-noise amplifiers. This station operated by CSIRO with assistance from a ESA engineering and operations team, provided support to the GIOTTO mission for reception of the 46 kbs high speed telemetry format which is vital to success of the GIOTTO mission at time of Cometary Encounter. Additionally, the DFVLR Weilheim station was modified to include the newly developed ESOC deep space tracking system which was also installed at the Carnarvon Station. The paper discusses in some detail the network of tracking stations which provided the Control Centre at ESOC in Darmstadt, F.R.G. with the data which was vital to the success of the mission. Because the launch date of GIOTTO was a date which could not be rescheduled, the design installation, integration and testing of the complete GIOTTO mission operations system was an extremely time critical activity. Without the “ground segment” in a fully functional state, the launch of GIOTTO could not take place. The activities leading to the successful completion of the GIOTTO mission operations system are described in some detail with emphasis on the final testing carried out in early 1985. One important factor which is sometimes overlooked by authors describing the GIOTTO mission is that, whereas NASA has had for many years a world-wide deep space network available for its deep space missions, ESA had to start from scratch in its task of building a system capable of controlling the GIOTTO mission to Halley's Comet. The task of spacecraft operations can never be discussed separately from the system required to provide the necessary control of the mission. This paper will concentrate to some extent in this aspect as experienced during the flight to the comet and the rendezvous on the night of 13 March 1986.