Comet Grigg–Skjellerup (formally designated 26P/Grigg–Skjellerup) is a periodic comet. It was visited by the Giotto probe in July 1992. The spacecraft came as close as 200 km, but could not take pictures because some instruments were damaged from its encounter with Halley's Comet. The comet last came to perihelion (closest approach to the Sun) on 25 December 2023,

Exploration

In 1987, Grigg–Skjellerup was selected as the second comet targeted by the Giotto mission due to its perihelion in 1992 occurring very close to the Earth's orbit itself.

By February 1990, the mission control at the European Space Agency reactivated the spacecraft after four years of hibernation following the Halley mission, subsequently executing the first ever Earth flyby in space exploration history to reach 26P on July 1990. Giotto reached Grigg–Skjellerup on 10 July 1992 at a distance of , much closer than its approach to Halley's Comet, but was unable to obtain images as its camera was destroyed during the Halley rendezvous in 1986. Despite this, the spacecraft was able to measure the interaction of the solar wind and how it affects the coma of this comet.

Giotto was deactivated just 13 days after its flyby of Grigg–Skjellerup on 23 July 1992.

Cancelled proposals

In 1972, a NASA spacecraft mission based from the Explorer 47/50 satellite called Cometary Explorer was proposed to intercept Grigg–Skjellerup at a distance of by April 1977, with an option to flyby 21P/Giacobini–Zinner on a potential mission extension in 1979. This would serve as a precursor mission for an eventual mission to Halley in 1986, however it was rejected due to budget cuts.

  • In Neal Stephenson's science fiction novel Seveneves, 26P/Grigg–Skjellerup serves as a potential source of water and rocket propellant for the "Cloud Ark" survivors, and is frequently referred to by the nickname "Greg's Skeleton" by way of homophonic transformation.

See also

  • List of minor planets and comets visited by spacecraft

References

  • 26P/Grigg–Skjellerup at Gary W. Kronk's Cometography
  • 26P/Grigg–Skjellerup at Seiichi Yoshida's website
  • ESA website about 26P/Grigg–Skjellerup
  • Recovery of comet 26P/Grigg–Skjellerup (Remanzacco Observatory : 26 December 2012)