Comet Hartley 2 much smaller than previously anticipated: JPL

21:17, November 05, 2010      

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Comet Hartley 2, which had a close encounter with a nine year-old spacecraft, is found to be much smaller than previously anticipated, NASA's Jet Propulsion Loboratory (JPL) said on Thursday.

The new finding is based on images taken from spacecraft Deep Impact which successfully flew by Hartley 2 at about 7 a.m. PDT (10 a.m. EDT) Thursday, the JPL said.

The images show that Hartley 2 is just one-hundredth the size of comet Tempel 1, said the JPL, headquartered in Pasadena, Los Angeles.

Scientists had previously anticipated that Hartley 2 was one-seventh the size of Tempel 1, the first comet Deep Impact flew past in 2005.

Scientists overestimated the size of Hartley 2 because it releases almost the same amount of gas and dust into the surrounding environment as Tempel 1, the JPL said.

Thursday's close encounter between Deep Impact and Hartley 2 gave astronomers new information about how material spews off comets and forms their frozen tails, the JPL said.

"For the first time, we may be able to connect activity to individual features on the nucleus," said JPL principal investigator Michael A'Hearn.

Deep Impact, launched in 2001, lobbed a small sacrificial object called an impactor into Tempel 1, allowing scientists to measure what type of material blew off that comet.

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