Bruce Murray Space Image LibraryComets visited by spacecraft Comets visited by spacecraft As of November 5, 2010, five comet nuclei had been directly imaged by flyby spacecraft. They are shown here to scale with each other, at 20 meters per pixel (in the click to enlarge version). Halley: Russian Academy of Sciences / Ted Stryk. Tempel 1 and Hartley 2: NASA / JPL / UMD. Borrelly: NASA / JPL / Ted Stryk. Wild 2: NASA / JPL. Montage by Emily Lakdawalla.