Comet Halley's Gas Composition and Extended Sources: Results From the Neutral Mass Spectrometer on Giotto

摘要

The Neutral Mass Spectrometer on the Giotto spacecraft established that H_2O is the dominant species in Comet Halley's volatiles and determined the abundance of more than 10 parent species. The instrument discovered strong extended H_2CO and CO sources in the coma of Comet Halley. Polymerized H_2CO associated with the cometary dust and evaporating slowly as the monomer is most likely the extended H_2CO source. Photodissociation of the H_2CO into CO fully accounts for the extended CO source.