... A chance encounter with a comet . ... Gloeckler is the principal investigator on the Solar Wind Ion Composition Spectrometer (SWICS) aboard Ulysses, which measured the composition and speed of the comet tail and solar wind. ... Not only did SWICS detect unexpected ions in the comet tail, it found that the tail had a major impact on the surrounding solar wind. ... In 1996, Ulysses passed through the tail of comet Hyakutake and measurements indicated its tail didn't slow the solar wind at all. ...