jeudi 9 juillet 2015

Pluto and Charon: New Horizons’ Dynamic Duo












NASA - New Horizons Mission logo.

July 9, 2015


Image above: New Horizons was about 3.7 million miles (6 million kilometers) from Pluto and Charon when it snapped this portrait late on July 8, 2015. Most of the bright features around Pluto’s edge are a result of image processing, but the bright sliver below the dark “whale,” which is also visible in unprocessed images, is real. Image Credits: NASA-JHUAPL-SWRI.


Image above: This is the same image of Pluto and Charon from July 8, 2015; color information obtained earlier in the mission from the Ralph instrument has been added. Image Credits: NASA-JHUAPL-SWRI.


Image above: Image of Pluto only from the New Horizons’ Long Range Reconnaissance Imager (LORRI), July 8, 2015. Most of the bright features around Pluto’s edge are a result of image processing, but the bright sliver below the dark “whale,” which is also visible in unprocessed images, is real. Image Credits: NASA-JHUAPL-SWRI.


Image above: Image of Charon only from the New Horizons’ Long Range Reconnaissance Imager (LORRI), July 8, 2015. Image Credits: NASA-JHUAPL-SWRI.

They’re a fascinating pair: Two icy worlds, spinning around their common center of gravity like a pair of figure skaters clasping hands. Scientists believe they were shaped by a cosmic collision billions of years ago, and yet, in many ways, they seem more like strangers than siblings.

A high-contrast array of bright and dark features covers Pluto’s surface, while on Charon, only a dark polar region interrupts a generally more uniform light gray terrain. The reddish materials that color Pluto are absent on Charon. Pluto has a significant atmosphere; Charon does not. On Pluto, exotic ices like frozen nitrogen, methane, and carbon monoxide have been found, while Charon’s surface is made of frozen water and ammonia compounds. The interior of Pluto is mostly rock, while Charon contains equal measures of rock and water ice.

“These two objects have been together for billions of years, in the same orbit, but they are totally different,” said Principal Investigator Alan Stern of the Southwest Research Institute (SwRI), Boulder, Colorado

New Horizons spacecraft orbiting Pluto. Image Credits: NASA

Charon is about 750 miles (1200 kilometers) across, about half the diameter of Pluto—making it the solar system’s largest moon relative to its planet. Its smaller size and lower surface contrast have made it harder for New Horizons to capture its surface features from afar, but the latest, closer images of Charon’s surface show intriguing fine details.

Newly revealed are brighter areas on Charon that members of the mission’s Geology, Geophysics and Imaging team (GGI) suspect might be impact craters. If so, the scientists would put them to good use. “If we see impact craters on Charon, it will help us see what’s hidden beneath the surface,” said GGI leader Jeff Moore of NASA’s Ames Research Center. “Large craters can excavate material from several miles down and reveal the composition of the interior.”

In short, said GGI deputy team leader John Spencer of SwRI, “Charon is now emerging as its own world. Its personality is beginning to really reveal itself.”

video
 NASA's New Horizons spacecraft arrives at Pluto on July 14th

Video above: NASA's New Horizons spacecraft arrives at Pluto on July 14th; a journey lasting nearly 10 years and traveling over 3 billion miles. Watch coverage of the historic flyby of Pluto on NASA Television as NASA counts down to the Pluto encounter of a lifetime.
http://www.nasa.gov/multimedia/nasatv/index.html

The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, designed, built, and operates the New Horizons spacecraft, and manages the mission for NASA's Science Mission Directorate. The Southwest Research Institute, based in San Antonio, 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.

For more information about New Horizons mission, visit: http://www.nasa.gov/mission_pages/newhorizons/main/index.html

Images (mentioned), Video, Text, Credits: NASA/NASA TV/Tricia Talbert.

Greetings, Orbiter.ch

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