[meteorite-list] NASA's New Horizons Team Finds Haze, Flowing Ice on Pluto

[Ron Baalke]

July 24, 2015

RELEASE 15-158

NASA's New Horizons Team Finds Haze, Flowing Ice on Pluto

Flowing ice and a surprising extended haze are among the newest discoveries 
from NASA's New Horizons mission, which reveal distant Pluto to be an icy 
world of wonders.

"We knew that a mission to Pluto would bring some surprises, and now -- 10 
days after closest approach -- we can say that our expectation has been more 
than surpassed," said John Grunsfeld, NASA's associate administrator for 
the Science Mission Directorate. "With flowing ices, exotic surface 
chemistry, mountain ranges, and vast haze, Pluto is showing a diversity of 
planetary geology that is truly thrilling."

Just seven hours after closest approach, New Horizons aimed its Long Range 
Reconnaissance Imager (LORRI) back at Pluto, capturing sunlight streaming 
through the atmosphere and revealing hazes as high as 80 miles (130 
kilometers) above Pluto's surface. A preliminary analysis of the image 
shows two distinct layers of haze -- one about 50 miles (80 kilometers) above 
the surface and the other at an altitude of about 30 miles (50 kilometers).

"My jaw was on the ground when I saw this first image of an alien 
atmosphere in the Kuiper Belt," said Alan Stern, principal investigator for 
New Horizons at the Southwest Research Institute (SwRI) in Boulder, Colorado. 
"It reminds us that exploration brings us more than just incredible 
discoveries -- it brings incredible beauty."

Studying Pluto's atmosphere provides clues as to what's happening below.

"The hazes detected in this image are a key element in creating the complex 
hydrocarbon compounds that give Pluto's surface its reddish hue," said 
Michael Summers, New Horizons co-investigator at George Mason University in 
Fairfax, Virginia.

Models suggest the hazes form when ultraviolet sunlight breaks up methane gas 
particles -- a simple hydrocarbon in Pluto's atmosphere. The breakdown of 
methane triggers the buildup of more complex hydrocarbon gases, such as 
ethylene and acetylene, which also were discovered in Pluto's atmosphere by 
New Horizons. As these hydrocarbons fall to the lower, colder parts of the 
atmosphere, they condense into ice particles that create the hazes. 
Ultraviolent sunlight chemically converts hazes into tholins, the dark 
hydrocarbons that color Pluto's surface.

Scientists previously had calculated temperatures would be too warm for hazes 
to form at altitudes higher than 20 miles (30 kilometers) above Pluto's 
surface.

"We're going to need some new ideas to figure out what's going on," 
said Summers.

The New Horizons mission also found in LORRI images evidence of exotic ices 
flowing across Pluto's surface and revealing signs of recent geologic 
activity, something scientists hoped to find but didn't expect. 

The new images show fascinating details within the Texas-sized plain, 
informally named Sputnik Planum, which lies within the western half of 
Pluto's heart-shaped feature, known as Tombaugh Regio. There, a sheet of 
ice clearly appears to have flowed -- and may still be flowing -- in a manner 
similar to glaciers on Earth.

"We've only seen surfaces like this on active worlds like Earth and 
Mars," said mission co-investigator John Spencer of SwRI. "I'm really 
smiling."

Additionally, new compositional data from New Horizons' Ralph instrument 
indicate the center of Sputnik Planum is rich in nitrogen, carbon monoxide, 
and methane ices.

"At Pluto's temperatures of minus-390 degrees Fahrenheit, these ices can 
flow like a glacier," said Bill McKinnon, deputy leader of the New Horizons 
Geology, Geophysics and Imaging team at Washington University in St. Louis. 
"In the southernmost region of the heart, adjacent to the dark equatorial 
region, it appears that ancient, heavily-cratered terrain has been invaded by 
much newer icy deposits."

View a simulated flyover using New Horizons' close-approach images of 
Sputnik Planum and Pluto's newly-discovered mountain range, informally 
named Hillary Montes, in the video below:

http://go.nasa.gov/1MMEdTb

The New Horizons mission will continue to send data stored in its onboard 
recorders back to Earth through late 2016. The spacecraft currently is 7.6 
million miles (12.2 million kilometers) beyond Pluto, healthy and flying 
deeper into the Kuiper Belt.

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. SwRI, 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 on the New Horizons mission, including fact sheets, 
schedules, video and images, visit:

http://www.nasa.gov/newhorizons

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