6P/d'Arrest

6P/d'Arrest (also known as d'Arrest's Comet or Comet d'Arrest) is a periodic comet orbiting between Mars and Jupiter once every 6.54 years. It is the second of three comets discovered by German astronomer, Heinrich Ludwig d'Arrest.Template:Efn

Observational history

It was first observed by Heinrich Ludwig d'Arrest, in Leipzig, Germany, between June 28–30, 1851.Template:R In 1991, a study conducted by Andrea Carusi and Giovanni B. Valsecchi (Istituto Astrofisica Spaziale, Rome), alongside Ľubor Kresák and Margita Kresáková (Slovak Astronomical Institute, Bratislava) independently suggested that this comet is the same as the comet previously observed by Philippe de La Hire in 1678.Template:R

The comet passed within Template:Convert from Earth on August 12, 1976.Template:R Its apparition in 2015 was unfavorable as it had a solar elongation of less than 30 degrees from October 2014 until May 2015. 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.Template:R

Physical characteristics

Guring its 2008 apparition, infrared spectroscopy conducted at the Keck Observatory has detected emissions of [[water|Template:Chem]], [[methanol|Template:Chem]], [[ethane|Template:Chem]], [[formaldehyde|Template:Chem]] and [[ammonia|Template:Chem]] from its coma, where the latter three gases were found to be relatively depleted compared to other comets.Template:R

The comet nucleus is estimated at Template:Cvt in diameter.Template:R Photometric measurements in 1976 revealed a rotation period of around Template:Val hours,Template:R however this was revised after a periodogram analysis of its lightcurve in 2003 suggests that the comet has a longer rotation period, around Template:Val hours.Template:R

Exploration

File:6p d'Arrest.jpg

Long-exposure image of Comet d'Arrest taken by Elizabeth Roemer on 7 May 1970

A study in 1966 proposed a Mariner-type mission to 6P/d'Arrest planned to be launched from an Atlas-Centaur by April 1976, arriving at the comet at a distance of Template:Cvt about 115–145 days after launch, however this did not come to fruition.Template:R

6P/d was one of a trio of comets alongside 2P/Encke and 73P/Schwassmann–Wachmann targeted by the ill-fated CONTOUR mission,Template:R which was launched but lost contact soon after reaching orbit in 2002. Had it been functional, the planned date for CONTOUR's flyby of d'Arrest would have been 2008, after visiting two other comets.Template:R

Around 2007, 6P/d was one of nine comets examined for a preliminary comet sample return mission study.Template:R By the 2010s, three comet surface sample return missions (CONDOR, CORSAIR, and CAESAR) were selected as finalists for the New Frontiers Program, but the recently studied 67P/Churyumov–Gerasimenko and 88P/Howell were chosen as the selected targets. These proposals were ultimately not selected in favor of the Dragonfly mission to Titan.

See also

• List of missions to comets

External links

• Template:JPL Small Body
• 6P/d'Arrest at CometBase database
• Elements and Ephemeris for 6P/d'Arrest – Minor Planet Center
• 6P/d'Arrest – Seiichi Yoshida @ aerith.net
• 6P – Gary W. Kronk's Cometography