6P/d'Arrest (also known as d'Arrest's Comet or Comet d'Arrest) is a periodicJupiter-familycomet in the Solar System, orbiting between Mars and Jupiter. It passed 0.15124 AU (22,625,000 km; 14,059,000 mi) from the Earth on August 12, 1976.[5] The most recent perihelion passage took place on September 17, 2021, when the comet had a solar elongation of 95 degrees at approximately apparent magnitude of 10.[6]
The comet came to perihelion (closest approach to the Sun) on March 2, 2015,[6] but it was in an unfavorable apparition as it had a solar elongation of less than 30 degrees from October 2014 until May 2015.[9]
6P/d was one of a trio of comets targeted by the ill-fated CONTOUR mission, an unmanned discovery program mission, that was launched but contact was lost soon after reaching orbit. If it had been functional, the planned date for CONTOUR's study of d'Arrest would have been 2008, after visiting two other comets.[10]
Around 2007, 6P/d was one of nine comets examined for a comet sample return mission study.[11] In the 2010s a comet surface sample return mission was selected as the New Frontiers Program finalist, but the recently studied comet 67P was chosen as the selected target.