vendredi 8 janvier 2016

Particles ‘Go with the Flow’ on Pluto’s Surface & Icy Plains in Highest-Resolution Views












NASA - New Horizons Mission logo.

Jan. 8, 2016

Scientists from NASA’s New Horizons mission have combined data from two instruments to create this composite image of Pluto’s informally named Viking Terra area.


The combined data includes pictures taken by the spacecraft’s Long Range Reconnaissance Imager (LORRI) on July 14, 2015, from a range of about 31,000 miles (49,000 kilometers), showing features as small as 1,600 feet (480 meters) across. Draped over the LORRI mosaic is enhanced color data from the Ralph/Multispectral Visible Imaging Camera (MVIC), gathered about 20 minutes after the LORRI snapshots were taken, from a range of 21,000 miles (34,000 kilometers) and at a resolution of about 2,100 feet (650 meters) per pixel. The entire scene is 160 miles (250 kilometers) across.

Among the features scientists find particularly interesting are the bright methane ices that condensed on many crater rims; the collection of dark red tholins (small soot-like particles generated from reactions involving methane and nitrogen in the atmosphere) in low areas, like the bottoms of craters; and the layering on the faces of steep cliffs and on crater walls.


In areas where the reddish material is thickest and the surface appears smooth, the material seems to have flowed into some channels and craters. Scientists say tholin deposits of that thickness aren’t usually mobile on large scales, suggesting that they might be riding along with ice flowing underneath, or being blown around by Pluto’s winds.

Pluto’s Icy Plains in Highest-Resolution Views from New Horizons 


NASA’s New Horizons spacecraft continues to transmit the sharpest views of Pluto that it obtained (and recorded) during its July 14, 2015 flyby. 

The newest image, returned on Dec. 24, extends New Horizons’ highest-resolution swath of Pluto to the center of the informally named Sputnik Planum, and nearly completes the set of highest-resolution images taken by New Horizons.

The pictures are part of a sequence taken near New Horizons’ closest approach to Pluto, with resolutions of about 250-280 feet (77-85 meters) per pixel – revealing features smaller than half a city block on Pluto’s surface. The images illustrate the polygonal or cellular pattern of the plains, which are thought to result from the convective churning of a deep layer solid, but mobile, nitrogen ice.

The images shown here form a strip 50 miles (80 kilometers) wide and more than 400 miles (700 kilometers) long, trending from the northwestern shoreline of Sputnik Planum and out across its icy plains. They were made with the telescopic Long Range Reconnaissance Imager (LORRI) aboard New Horizons, from a range of approximately 10,000 miles (17,000 kilometers), about 15 minutes before New Horizons’ closest approach to Pluto.

The surface of Sputnik Planum appears darker toward the shore (at top), possibly implying a change in composition or surface texture. The occasional raised, darker blocks at the cell edges are probably dirty water “icebergs” that are floating in denser solid nitrogen.

The images are six times better than the resolution of the global Pluto map New Horizons obtained, and five times better than the best images of Pluto’s cousin Triton, Neptune’s large moon, obtained by Voyager 2 in 1989.

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

Images, Text, Credits: Credits: NASA/JHUAPL/SwRI/Bill Keeter.

Greetings, Orbiter.ch

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