The Halley Multicolour Camera (HMC)

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HMC was the imaging system on the <a href="http://www.esrin.esa.it/"> European Space Agency's</a> <a href="http://www.mps.mpg.de/en/projekte/giotto/hmc/">Giotto</a> spacecraft and was the only remote sensing instrument on board which could look at the nucleus of comet Halley. It was built by a consortium led by the Max-Planck-Institut fuer Sonnensystemforschung.

HMC returned over 2000 images of the nucleus and the inner coma of comet Halley over a period of 3 hours. The most useful images were through four broad-band filters (clear, red, blue and orange). The first images were obtained at a scale of 17 km/px (20 times better resolution than simultaneous ground-based measurements) from a distance of 750,000 km. In these images the asymmetry of the dust coma could be clearly seen. The nucleus was detected for the first time 30 minutes before closest approach from a distance of 124,000 km. The best images were obtained 5 minutes before closest approach and showed the whole nucleus and dust jets streaming away from active regions on the surface. All data were transmitted immediately in case the spacecraft or the camera were destroyed during the fly-by. To facilitate this, smaller images centred on the brightest part of the scene were transmitted in the last 5 minutes. These showed parts of the nucleus in ever increasing detail revealing topographic features on the surface.
Closest approach occurred at 00:03:01.84 UT on March 14, 1986, at a distance of 596 km from the centre of the nucleus.

Copyright:
The images shown herein may be used for educational purposes if the source (MPS) is given. However, all images herein are © MPS, 1986, 1996 and may not be used for commercial purposes without the permission of H.U. Keller at the Max-Planck-Institut fuer Sonnensystemforschung, Katlenburg-Lindau, Germany.