[meteorite-list] Increasing Variety on Pluto's Close Approach Hemisphere, and a 'Dark Pole' on Charon

[Ron Baalke]

http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20150622-3

Increasing Variety on Pluto's Close Approach Hemisphere, and a "Dark Pole" on Charon
June 22, 2015

[Images]
Features on the Close Approach Hemisphere: These images, taken by New 
Horizons' Long Range Reconnaissance Imager (LORRI), show numerous large-scale 
features on Pluto's surface. The distance to Pluto ranges from 47 million 
kilometers (about 29 million miles) on June 5 to 31 million kilometers 
(19 million miles) on June 18. When various large, dark and bright regions 
appear near limbs, they give Pluto a distinct, but false, non-spherical 
appearance. Pluto is known to be almost perfectly spherical from previous 
data. These images are displayed at four times the native LORRI image 
size, and have been processed using a method called deconvolution, which 
sharpens the original images to enhance features on Pluto. 

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest 
Research Institute

A Dark Mystery on Charon: These recent images show the discovery of significant 
surface details on Pluto's largest moon, Charon. They were taken by the 
New Horizons Long Range Reconnaissance Imager (LORRI) on June 18, 2015. 
The image on the left is the original image, displayed at four times the 
native LORRI image size. After applying a technique that sharpens an image 
called deconvolution, details become visible on Charon, including a distinct 
dark pole. Deconvolution can occasionally introduce "false" details, so 
the finest details in these pictures will need to be confirmed by images 
taken from closer range in the next few weeks.                        
     

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest 
Research Institute

NASA's New Horizons spacecraft doesn't pass Pluto until July 14 - but 
the mission team is making new discoveries as the piano-sized probe bears 
down on the Pluto system.

In a long series of images obtained by New Horizons' telescopic Long Range 
Reconnaissance Imager (LORRI) May 29-June 19, Pluto and its largest moon, 
Charon, appear to more than double in size. From this rapidly improving 
imagery, scientists on the New Horizons team have found that the "close 
approach hemisphere" on Pluto that New Horizons will fly over has the 
greatest variety of terrain types seen on the planet so far. They have 
also discovered that Charon has a "dark pole" - a mysterious dark region 
that forms a kind of anti-polar cap.

"This system is just amazing," said Alan Stern, New Horizons Principal 
Investigator, from the Southwest Research Institute, Boulder, Colorado. 
"The science team is just ecstatic with what we see on Pluto's close approach 
hemisphere: Every terrain type we see on the planet - including both the 
brightest and darkest surface areas - are represented there, it's a wonderland!

"And about Charon - wow - I don't think anyone expected Charon to reveal a 
mystery like dark terrains at its pole," he continued. "Who ordered that?"

New Horizons scientists use a technique called deconvolution to sharpen 
the raw, unprocessed pictures that the spacecraft beams back to Earth; 
the contrast in these latest images has also been stretched to bring out 
additional details. Deconvolution can occasionally produce artifacts, 
so the team will be carefully reviewing newer images taken from closer 
range to determine whether some of the tantalizing details seen in these 
images persist. Pluto's non-spherical appearance in these images is not 
real; it results from a combination of the image-processing technique 
and Pluto's large variations in surface brightness.

"The unambiguous detection of bright and dark terrain units on both Pluto 
and Charon indicates a wide range of diverse landscapes across the pair," 
said science team co-investigator and imaging lead Jeff Moore, of NASA 
Ames Research Center, Mountain View, California. "For example, the bright 
fringe we see on Pluto may represent frost deposited from an evaporating 
polar cap, which is now in summer sun."

New Horizons is approximately 2.9 billion miles (4.7 billion kilometers) 
from Earth and just 16 million miles (25 million kilometers) from Pluto. 
The spacecraft and payload are in good health and operating normally. 

[Movie]
Features on Pluto and Charon: Over the course of this "movie," assembled 
from a long series of images obtained by New Horizons' telescopic Long 
Range Reconnaissance Imager (LORRI) May 29-June 19, Pluto and its largest 
moon, Charon, appear to more than double in size. From this rapidly improving 
imagery, scientists on the New Horizons team have found that the "close 
approach hemisphere" on Pluto that New Horizons will fly over has the 
greatest variety of terrain types seen on the planet so far. The movie 
is "Plutocentric," meaning that Charon is shown as it moves in relation 
to Pluto, which is digitally centered in the movie.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest 
Research Institute