[meteorite-list] New Horizons Camera Spots Pluto's Largest Moon (Charon)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 10 Jul 2013 12:47:40 -0700 (PDT)
Message-ID: <201307101947.r6AJlel8005973_at_zagami.jpl.nasa.gov>


Charon Revealed!
New Horizons Camera Spots Pluto's Largest Moon

July 10, 2013

NASA's Pluto-bound New Horizons spacecraft, using its highest-resolution
telescopic camera, has spotted Pluto's Texas-sized, ice-covered moon
Charon for the first time. This represents a major milestone on the
spacecraft's 9?-year journey to conduct the initial reconnaissance of
the Pluto system and the Kuiper Belt and, in a sense, begins the
mission's long-range study of the Pluto system.

Pluto and Charon: New Horizons LOng Range Reconnaissance Imager
(LORRI) composite image showing the detection of Pluto's largest moon,
Charon, cleanly separated from Pluto itself. The frame on the left is an
average of six different LORRI images, each taken with an exposure time
of 0.1 second. The frame to the right is the same composite image but
with Pluto and Charon circled; Pluto is the brighter object near the
center and Charon is the fainter object near its 11 o'clock position.
The circles also denote the predicted locations of the objects, showing
that Charon is where the team expects it to be, relative to Pluto. No
other Pluto system objects are seen in these images.

When these images were taken on July 1 and July 3, 2013, the New
Horizons spacecraft was still about 550 million miles (880 million
kilometers) from Pluto. On July 14, 2015, the spacecraft is scheduled to
pass just 7,750 miles (12,500 kilometers) above Pluto's surface, where
LORRI will be able to spot features about the size of a football field.
(Credit: NASA/Johns Hopkins University Applied Physics
Laboratory/Southwest Research Institute)

The largest of Pluto's five known moons, Charon orbits about 12,000
miles (more than 19,000 kilometers) away from Pluto itself. As seen from
New Horizons, that's only about 0.01 degrees away.

"The image itself might not look very impressive to the untrained eye,
but compared to the discovery images of Charon from Earth, these
'discovery' images from New Horizons look great!" says New Horizons
Project Scientist Hal Weaver, of the Johns Hopkins University Applied
Physics Laboratory, Laurel, Md. "We're very excited to see Pluto and
Charon as separate objects for the first time from New Horizons."

The spacecraft was still 550 million miles from Pluto - farther than the
distance from Earth to Jupiter - when its LOng Range Reconnaissance
Imager (LORRI) snapped a total of six images: three on July 1 and three
more on July 3. LORRI's excellent sensitivity and spatial resolution
revealed Charon at exactly the predicted offset from Pluto, 35 years
after the announcement of Charon's discovery in 1978
<http://www.pluto.jhuapl.edu/overview/piPerspective.php> by James
Christy of the Naval Observatory.

"In addition to being a nice technical achievement, these new LORRI
images of Charon and Pluto should provide some interesting science too,"
says New Horizons Principal Investigator Alan Stern, of the Southwest
Research Institute. New Horizons is viewing Pluto and Charon at solar
phase angles (the angles between the Sun, Pluto and spacecraft) much
larger than can be achieved from observatories located on or near the
Earth, potentially yielding important information about the surface
properties of Charon and Pluto - perhaps the existence of an overlying
layer of fine particles, for example.

'We're excited to have our first pixel on Charon," Stern continues, "but
two years from now, near closest approach, we'll have almost a million
pixels on Charon - and I expect we'll be about a million times happier too!"

35 Years Later: Charon is visible as a "bump" moving around Pluto
in the moon's discovery images (right), taken with the 1.55-meter (61-inch) Kaj
Strand Astrometric Reflector at the U.S. Naval Observatory's Flagstaff
Station in 1978. More than three decades later, Charon is visible for
the first time in pictures (left) taken by the Pluto-bound New Horizons
Received on Wed 10 Jul 2013 03:47:40 PM PDT

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