[meteorite-list] NASA's New Horizons Discovers Frozen Plains in the Heart of Pluto's 'Heart'

[Ron Baalke]

http://www.nasa.gov/press-release/nasa-s-new-horizons-discovers-frozen-plains-in-the-heart-of-pluto-
s-heart

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NASA's New Horizons Discovers Frozen Plains in the Heart of Pluto's 'Heart'
July 17, 2015

[Image]
In the center left of Pluto's vast heart-shaped feature - informally named 
'Tombaugh Regio" - lies a vast, craterless plain that appears to be no 
more than 100 million years old, and is possibly still being shaped by 
geologic processes. This frozen region is north of Pluto's icy mountains 
and has been informally named Sputnik Planum (Sputnik Plain), after Earth's 
first artificial satellite. The surface appears to be divided into irregularly-shaped 
segments that are ringed by narrow troughs. Features that appear to be 
groups of mounds and fields of small pits are also visible. This image 
was acquired by the Long Range Reconnaissance Imager (LORRI) on July 14 
from a distance of 48,000 miles (77,000 kilometers). Features as small 
as one-half mile (1 kilometer) across are visible. The blocky appearance 
of some features is due to compression of the image.
Credits: NASA/JHUAPL/SWRI

In the latest data from NASA's New Horizons spacecraft, a new close-up 
image of Pluto reveals a vast, craterless plain that appears to be no 
more than 100 million years old, and is possibly still being shaped by 
geologic processes. This frozen region is north of Pluto's icy mountains, 
in the center-left of the heart feature, informally named "Tombaugh Regio"
(Tombaugh Region) after Clyde Tombaugh, who discovered Pluto in 1930.

"This terrain is not easy to explain," said Jeff Moore, leader of the 
New Horizons Geology, Geophysics and Imaging Team (GGI) at NASA's Ames 
Research Center in Moffett Field, California. "The discovery of vast, 
craterless, very young plains on Pluto exceeds all pre-flyby expectations."

This fascinating icy plains region -- resembling frozen mud cracks on 
Earth -- has been informally named "Sputnik Planum" (Sputnik Plain) after 
the Earth's first artificial satellite. It has a broken surface of irregularly-shaped 
segments, roughly 12 miles (20 kilometers) across, bordered by what appear 
to be shallow troughs. Some of these troughs have darker material within 
them, while others are traced by clumps of hills that appear to rise above 
the surrounding terrain. Elsewhere, the surface appears to be etched by 
fields of small pits that may have formed by a process called sublimation, 
in which ice turns directly from solid to gas, just as dry ice does on 
Earth.

Scientists have two working theories as to how these segments were formed. 
The irregular shapes may be the result of the contraction of surface materials, 
similar to what happens when mud dries.  Alternatively, they may be a 
product of convection, similar to wax rising in a lava lamp. On Pluto, 
convection would occur within a surface layer of frozen carbon monoxide, 
methane and nitrogen, driven by the scant warmth of Pluto's interior.

Pluto's icy plains also display dark streaks that are a few miles long. 
These streaks appear to be aligned in the same direction and may have 
been produced by winds blowing across the frozen surface.

The Tuesday "heart of the heart" image was taken when New Horizons was 
48,000 miles (77,000 kilometers) from Pluto, and shows features as small 
as one-half mile (1 kilometer) across. Mission scientists will learn more 
about these mysterious terrains from higher-resolution and stereo images 
that New Horizons will pull from its digital recorders and send back to 
Earth during the next year.                                           
                     
The New Horizons Atmospheres team observed Pluto's atmosphere as far as 
1,000 miles (1,600 kilometers) above the surface, demonstrating that Pluto's 
nitrogen-rich atmosphere is quite extended. This is the first observation 
of Pluto's atmosphere at altitudes higher than 170 miles above the surface 
(270 kilometers).

The New Horizons Particles and Plasma team has discovered a region of 
cold, dense ionized gas tens of thousands of miles beyond Pluto -- the 
planet's atmosphere being stripped away by the solar wind and lost to 
space.

"This is just a first tantalizing look at Pluto's plasma environment," 
said New Horizons co-investigator Fran Bagenal, University of Colorado, 
Boulder.

"With the flyby in the rearview mirror, a decade-long journey to Pluto 
is over --but, the science payoff is only beginning," said Jim Green, 
director of Planetary Science at NASA Headquarters in Washington. "Data 
from New Horizons will continue to fuel discovery for years to come." 
  
Alan Stern, New Horizons principal investigator from the Southwest Research 
Institute (SwRI), Boulder, Colorado, added, "We've only scratched the 
surface of our Pluto exploration, but it already seems clear to me that 
in the initial reconnaissance of the solar system, the best was saved 
for last."

New Horizons is part of NASA's New Frontiers Program, managed by the agency's 
Marshall Space Flight Center in Huntsville, Alabama. 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 leads the mission, science team, payload 
operations and encounter science planning.

Follow the New Horizons mission on Twitter and use the hashtag #PlutoFlyby 
to join the conversation. Live updates are also available on the mission 
Facebook page.

For more information on the New Horizons mission, including fact sheets, 
schedules, video and new images, visit:

http://www.nasa.gov/newhorizons

and

http://solarsystem.nasa.gov/planets/plutotoolkit.cfm

-end-

Dwayne Brown / Laurie Cantillo
Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown at nasa.gov / laura.l.cantillo at nasa.gov

Mike Buckley
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
240-228-7536
michael.buckley at jhuapl.edu

Maria Stothoff
Southwest Research Institute, San Antonio
210-522-3305
maria.stothoff at swri.org