New cometary phenomenon greets approaching spacecraft
Recent observations of Comet 103P/Hartley have scientists scratching
their heads while they anticipate a flyby of the small, icy world
October 26, 2010
A phenomenon was recorded by imagers aboard NASA's Deep Impact spacecraft from September 9 to 17 during pre-planned scientific observations of Comet 103P/Hartley. These observations, when coupled with expected images during the closest encounter with Hartley November 4, will become the most detailed look yet at a comet's activity during its pass through the inner solar system.
NASA's Deep Impact/EPOXI spacecraft flew past Earth June 27, 2010, to get a boost from Earth’s gravity. It is now on its way to comet Hartley 2, depicted in this artist’s concept, with a planned flyby this fall.
Photo by NASA/JPL-Caltech
"On Earth, cyanide is known as a deadly gas. In space it's known as one of the most easily observed ingredients that is always present in a comet," said Mike A'Hearn from the University of Maryland, College Park. "Our observations indicate that cyanide released by the comet increased by a factor of five over an 8-day period in September without any increase in dust emissions. We have never seen this kind of activity in a comet before, and it could affect the quality of observations made by astronomers on the ground."
The new phenomenon is unlike typical cometary outbursts, which have sudden onsets and are usually accompanied by considerable dust. It also seems unrelated to the cyanide jets that are sometimes seen in comets. The EPOXI science team believes that astronomers and interested observers viewing the comet from Earth should be aware of this type of activity when planning observations and interpreting their data.
"If observers monitoring Hartley 2 do not take into account this new phenomenon, they could easily get the wrong picture of how the comet is changing as it approaches and recedes from the Sun," said A'Hearn.
Cyanide is a carbon-based molecule. It is believed that billions of years ago, a bombardment of comets carried cyanide and other building blocks of life to Earth.