[meteorite-list] 85 Years after Pluto's Discovery, New Horizons Spots Small Moons Orbiting Pluto

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 20 Feb 2015 16:04:26 -0800 (PST)
Message-ID: <201502210004.t1L04QId011633_at_zagami.jpl.nasa.gov>

http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20150218


85 Years after Pluto's Discovery, New Horizons Spots Small Moons Orbiting Pluto
February 18, 2015

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See the Pluto Discovery Images

http://solarsystem.nasa.gov/multimedia/display.cfm?Category=Planets&IM_ID=19989
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Exactly 85 years after Clyde Tombaugh's historic discovery of Pluto, the
NASA spacecraft set to encounter the icy planet this summer is providing
its first views of the small moons orbiting Pluto.

The moons Nix and Hydra are visible in a series of images taken by the
New Horizons spacecraft from Jan. 27-Feb. 8, at distances ranging from
about 125 million to 115 million miles (201 million to 186 million
kilometers). The long-exposure images offer New Horizons' best view yet
of these two small moons circling Pluto, which Tombaugh discovered at
Lowell Observatory in Flagstaff, Arizona, on Feb. 18, 1930.

"Professor Tombaugh's discovery of Pluto was far ahead its time,
heralding the discovery of the Kuiper Belt and a new class of planet,"
says Alan Stern, New Horizons principal investigator from Southwest
Research Institute, Boulder, Colorado. "The New Horizons team salutes
his historic accomplishment."

Assembled into a seven-frame movie, the new images provide the
spacecraft's first extended look at Hydra (identified by a yellow
diamond) and its first-ever view of Nix (orange diamond). The right-hand
image set has been specially processed to make the small moons easier to
see.

"It's thrilling to watch the details of the Pluto system emerge as we
close the distance to the spacecraft's July 14 encounter," says New
Horizons science team member John Spencer, also from Southwest Research
Institute. "This first good view of Nix and Hydra marks another major
milestone, and a perfect way to celebrate the anniversary of Pluto's
discovery."

These are the first of a series of long-exposure images that will
continue through early March, with the purpose of refining the team's
knowledge of the moons' orbits. Each frame is a combination of five
10-second images, taken with New Horizons' Long-Range Reconnaissance
Imager (LORRI) using a special mode that combines pixels to increase
sensitivity at the expense of resolution. At left, Nix and Hydra are
just visible against the glare of Pluto and its large moon Charon, and
the dense field of background stars. The bright and dark streak
extending to the right of Pluto is an artifact of the camera
electronics, resulting from the overexposure of Pluto and Charon. As can
be seen in the movie, the spacecraft and camera were rotated in some of
the images to change the direction of this streak, in order to prevent
it from obscuring the two moons.

The right-hand images have been processed to remove most of Pluto and
Charon's glare, and most of the background stars. The processing leaves
blotchy and streaky artifacts in the images, as well as a few other
residual bright spots that are not real features, but makes Nix and
Hydra much easier to see. Celestial north is inclined 28 degrees
clockwise from the "up" direction in these images.

LORRI

Nix and Hydra were discovered by New Horizons team members in Hubble
Space Telescope images taken in 2005. Hydra, Pluto's outermost known
moon, orbits Pluto every 38 days at a distance of approximately 40,200
miles (64,700 kilometers), while Nix orbits every 25 days at a distance
of 30,260 miles (48,700 kilometers). Each moon is probably between 25-95
miles (approximately 40- 150 kilometers) in diameter, but scientists
won't know their sizes more precisely until New Horizons obtains
close-up pictures of both of them in July. Pluto's two other small
moons, Styx and Kerberos, are still smaller and too faint to be seen by
New Horizons at its current range to Pluto; they will become visible in
the months to come.

The Johns Hopkins University Applied Physics Laboratory manages the New
Horizons mission for NASA's Science Mission Directorate in Washington.
Alan Stern, of the Southwest Research Institute (SwRI), headquartered in
San Antonio, is the principal investigator and leads the mission. SwRI
leads the science team, payload operations, and encounter science
planning. New Horizons is part of the New Frontiers Program managed by
NASA's Marshall Space Flight Center in Huntsville, Alabama. APL
designed, built and operates the spacecraft.

/Image credits: NASA/Johns Hopkins University Applied Physics
Laboratory/Southwest Research Institute./

Nix Hydra
Received on Fri 20 Feb 2015 07:04:26 PM PST