Pluto-bound Spacecraft Spots its Target

A white arrow marks Pluto in this New Horizons Long Range Reconnaissance Imager (LORRI) picture taken Sept. 21, 2006, marking the spacecraft's first look at its target planet. CREDIT: NASA/JHUAPL/SwRI.

A NASA spacecraft hurtling away from Earth has caught the first glimpse of its distant destination: the dwarf planet Pluto.

The New Horizons probe, set to swing by Pluto and its moons in 2015, plucked the small planet from a star-filled image during a checkout period using the spacecraft's long range camera [image].

"Finding Pluto in this dense star field really was like trying to find a needle in a haystack," said New Horizons principal investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado, in a statement.

Stern said astronomers took a page from the book of the late skywatcher Clyde Tombaugh--who discovered Pluto in 1930--and switched between different images of the same area, taken days apart, to hunt for the planet.

But where Tombaugh used photographic plates, New Horizons researchers relied on digital images taken of Pluto's expected location by their probe's Long Range Reconnaissance Imager (LORRI). The small planet was easily identified as it moved against the background of stars.

"We won't get useful science out of these first detections of Pluto," Stern said. "But during the next several years of approach, we'll use LORRI to study Pluto's brightness variation with our angle to the Sun to build a 'phase curve' we could never get from Earth or Earth orbit."

That should yield new details of Pluto's frigid surface well before New Horizons makes its flyby past the dwarf planet on July 14, 2015, he added.

In the meantime, New Horizons researchers are content to know that the probe's long-distance camera is working well, and eagerly awaiting next year's Feb. 28slingshot past Jupiter. The spacecraft was built for NASA by Johns Hopkins Applied Physics Laboratory, which is also managing the mission's more than nine-year flight.

Travelogue to Pluto

Since its Jan.19 launch, New Horizons has snapped photos of the asteroid JF56--during a June 13 pass--as well as the star Messier 7 and the gas giant Jupiter on its way to Pluto.

The Pluto portrait was taken between Sept. 21-24, stored aboard New Horizons and only recently relayed back home to Earth. New Horizons was about 2.6 billion miles (4.2 billion kilometers) from its planetary target at the time of the LORRI image.

"Those of us who calibrated LORRI on the ground and in flight are not surprised to see what it can do, but we are mighty grateful that LORRI has survived launch and its first several months in space without any loss of performance," said LORRI principal investigator Andy Cheng, of the Applied Physics Laboratory, in a statement.

NASA has billed New Horizons' journey as the U.S. space agency's fastest mission to date despite its long travel time. Stern and his fellow mission scientists are hoping to send their spacecraft past Pluto to visit at least one other icy object in the distant Kuiper Belt, which stretches beyond the orbit of Neptune. [Click here for a graphic of the probe's flight path.]

New Horizons is currently speeding through the solar system at about 20.8 kilometers per second with respect to the Sun. That's about 46,528 miles per hour (74,880 kilometers per hour).

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