Scientists Find Nitrogen Ice Glaciers on Pluto

Newly released close-up photographs from NASA’s New Horizons mission show evidence of exotic ice flow across dwarf-planet Pluto’s surface, indicating that Earth may not be the only planet with glacier-like geology. New Horizon’s Long-Range Reconnaissance Imager (LORRI) shows close-up photos of a sheet of ice that appears to have glided across Pluto’s surface in similar manner as glacier movement on Earth.

On Earth, melting glaciers are often characterized by surface flows around obstacles and towards the point of deepest depression, often creating swirl-shaped surfaces. New photos from the New Horizons mission show that Pluto too exhibits this characteristic warped surface.

Ice flow on the Northern region of Pluto’s Sputnik Plain
Flowing ices on Pluto, characterized by swirl-shaped patterns of light and dark. Credits: NASA.

According to Bill McKinnon, the deputy leader of New Horizons Geology, Geophysics, and Imaging team, Pluto’s frosty temperature of minus-390 degrees Fahrenheit allows these ices to move in a manner similar to those on Earth.

This movement might still be continuing, scientists speculate, but it is difficult to discern from still photographs whether Pluto’s frozen ice is still flowing.

The ice stems from the center of Sputnik Planum, a craterless plain lying in “the heart of the heart” of Pluto. According to NASA scientists, this plain, lying in the western half of the Tombaugh region, appears to be no more than 100 million years old, making it a relatively young surface of Pluto. This region is likely still be being shaped by geological processes.

NASA’s associate administrator for the Science Mission Directorate, John Grunsfeld, told NASA that the diverse and surprising findings of the New Horizons Pluto mission have been “truly thrilling.”

“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.”

Plutos Carbon Monoxide "Bulls-eye"
The carbon monoxide “bulls-eye” in the heart-shaped region of Pluto. Credits: NASA.

The ice that comprises the plain is primarily composed of nitrogen, although it is also carbon monoxide- and methane-rich. New Horizon’s Ralph Instrument reveals that the concentration of carbon monoxide in ice steadily increases towards the center of the heart’s “bulls-eye.”

These findings call into question the very definition of “glaciers,” and whether this geological term can be applied not only to other planets, but also to different chemical compositions of ice. Glaciers, as interpreted by the National Snow and Ice Data Center, are composed of fallen snow that compresses into large, thickened ice masses over a number of years. The chemical makeup of snow differs largely from Pluto’s nitrogen-, carbon monoxide-, and methane-rich ice makeup. For now, scientists and the media seem content to use the term “glacier-like” when referring to Pluto’s newly discovered nitrogen ice flow.

Through the New Horizons mission, NASA scientists have also discovered Pluto’s latitudinal planetary zones, and believe them to be caused by seasonal ice transport from the equator to the icy poles. Lending additional support to this theory, enhanced color images of the planet show that Pluto’s darkest terrains appear at the equator, while a seemingly whiter, icy expanse reigns in the northern polar region.

An enhanced color global view of Pluto.
Enhanced color global view of Pluto, taken 280,000 miles away. Credits: NASA.

Another region, the southern-most region of Pluto’s heart, Cthulhu Regio (one of the older, heavily-cratered regions of the planet) is also believed to be filled with newer icy deposits.

Plutos newfound haze
The newfound haze surrounding dwarf-planet Pluto. Credits: NASA.

The New Horizons mission has also discovered Pluto’s mountain ranges, exotic surface chemistry, and a peculiar haze surrounding the planet that extends as high as 80 miles above the planet’s surface.

Scientists and the public have been delighted with and captivated by the diverse and surprising findings of the New Horizons mission. A closer view of the distant dwarf planet has provided knowledge of Pluto’s features that are both similar to Earth’s, such as these glaciers, as well as those that are vastly different.

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