About half of the 10 instruments onboard Giotto were found to be still operational after the encounter with Comet Halley in 1986, having survived the bombardment of dust particles during the nucleus fly-by. So it was judged worthwhile to re-direct the spacecraft to fly past another comet (Grigg-Skjellerup, with a nucleus 100 times less active than Halley's), after the satellite went through a period of hibernation and had a close approach to Earth in 1990. The second encounter took place on 10 July 1992, and once again the experimenters gathered at the European Space Operations Centre (ESOC) in Damstadt, Germany, to monitor the event (and have some celebratory party!). Giotto had another Earth fly-by in July 1999, but no fuel was left onboard to permit the encounter with another comet.
Hans, John, Mark and Berend