Deep Impact, the spacecraft, acquired the first images of comet C/2012 S1 (ISON). The images were taken by the spacecraft's medium-resolution imager over a 36-hour period on January 17 and 18, 2013.
At that time Deep Impact was 793 million kilometers away from the comet, a Nasa statement said.
"The distance limits our bandwidth, so it's a little like communicating through a modem after being used to DSL. But, we're going to coordinate our science collection and playback so we maximize our return on this potentially spectacular comet," said Tim Larson, project manager for the Deep Impact spacecraft at Nasa's Jet Propulsion Laboratory in Pasadena, California.
ISON is lurking just inside of Jupiter at present. In November, it will come to within 1.6 million kilometers of the Sun, according to Nasa.
The intense heat will evaporate its ice and make it glow — thus making it visible from Earth.
The heat may be so great that the comet may completely burn up. If it survives, it will pass near the Earth in December.
But it will not be a threat to Earth — getting no closer to Earth than about 40 million miles on December 26, 2013.
Long-period comets like ISON are thought to arrive from the solar system's Oort cloud, a giant spherical cloud of icy bodies surrounding our solar system so far away its outer edge is about a third of the way to the nearest star (other than our sun).
Every once in a while, one of these loose conglomerations of ice, rock, dust and organic compounds is disturbed out of its established orbit in the Oort cloud by a passing star or the combined gravitational effects of the stars in the Milky Way galaxy.
With these gravitational nudges, so begins a comet's eons-long, arching plunge toward the inner solar system.
ISON was discovered on September 21, 2012, by two Russian astronomers using the International Scientific Optical Network's 40-centimeter telescope near Kislovodsk.
Nasa's near-earth object program office has determined that the comet is more than likely making it first-ever sweep through the inner solar system. Having not come this way before means the comet's pristine surface has a higher probability of being laden with volatile material just spoiling for some of the sun's energy to heat it up and help it escape.
With the exodus of these clean ices could come a boatload of dust, held in check since the beginnings of our solar system. This released gas and dust is what is seen on Earth as comprising a comet's atmosphere (coma) and tail.
Launched in January 2005, Deep Impact has traveled over 7 billion kilometers in space till date. It has executed close flybys of two comets — Tempel 1 and Hartley 2 — and performed scientific observations on two more — comet Garradd and now ISON, Nasa said.
The spacecraft finished its primary mission in 2007. Preliminary results indicate that although the comet is still in the outer solar system, more than 763 million kilometers from the sun, it is already active. As of Jan. 18, the tail extending from ISON's nucleus was already more than 40,000 miles (64,400 kilometers) long.
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