Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit in Siding Spring, Australia. Its diameter is estimated to be 1.2 to 1.6 kilometres (0.75 to 0.99 mi). Hartley 2 was the target of a flyby of the Deep Impact spacecraft, as part of the EPOXI mission, on November 4, 2010, which was able to approach within 700 kilometres of Hartley 2 as part of its extended mission. As of November 2010 Hartley 2 is the smallest comet which has been visited. It is the fifth comet visited by spacecraft, and the second comet visited by the Deep Impact spacecraft, which first visited Comet Tempel 1 on July 4, 2005.
One of the biggest comet findings coming out of the amazing images and data taken by the University of Maryland-led EPOXI mission as it zipped past comet Hartley 2 last week is that dry ice is the 'jet' fuel for this comet and perhaps many others. Read more
Herschel is taking part in an extraordinary worldwide astronomical campaign to study comet Hartley 2 before, during, and after the flyby by the NASA EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) mission, with closest approach on 4 November 2010. Hartley 2 passed just 0.11 AU (16.4 million km) from Herschel on 20 October 2010. Herschel has obtained unique sensitive far-infrared continuum images constraining the size of the large dust particles, while spectra reveal the distribution of water molecules released from the nucleus as about 230 kg of ices evaporate every second. Read more (328kb, PDF)
Nasa's Deep Impact probe has flown by Comet Hartley 2.
The first pictures revealed a roughly 1.5km-long, peanut-shaped object with jets of gas streaming from its surface. The pass, which occurred about 23 million km from Earth, was only the sixth time a spacecraft had made a close approach to a comet. Read more
This video clip was compiled from images taken by NASA's EPOXI mission spacecraft during its flyby of comet Hartley 2 on Nov. 4, 2010. During the encounter, the spacecraft and comet whisked past each other at a speed of 12.3 kilometres per second. The spacecraft came within about 700 kilometres of the comet's nucleus at the time of closest approach. Read more
About an hour after its closest approach of Hartley 2, Deep Impact downlinked five precious images taken during the nearest part of its flyby. Read more
NASA Mission Successfully Flies by Comet Hartley 2
NASA's EPOXI mission successfully flew by comet Hartley 2 at about 7 a.m. PDT (10 a.m. EDT) today, and the spacecraft has begun returning images. Hartley 2 is the fifth comet nucleus visited by a spacecraft. Scientists and mission controllers are currently viewing never-before-seen images of Hartley 2 appearing on their computer terminal screens. Read more
Almost a quarter of a century after he discovered it, Australian astronomer, Malcolm Hartley is about to finally see, up close and personal, the comet he gave his name to. Early tomorrow morning well before sunrise the NASA spacecraft EPOXI will do a fly-by, within 700 kilometres of the Hartley 2 comet. Read more