The latest data transmitted back to Earth by NASA’s New Horizons spacecraft includes newly-discovered evidence of exotic ices flowing across the surface of Pluto, as well as a stunning new nightside image of the dwarf planet that reveals higher-than-expected layers of haze.
That image, captured by the probe seven hours after its closest approach on July 14, depicts the atmosphere of Pluto as the dwarf planet is backlit by the sun. It was captured by the spacecraft’s Long Range Reconnaissance Imager (LORRI) instrument, according to the US space agency.
The sunlight streaming through the atmosphere revealed hazes reaching heights of more than 80 miles (130 km) above the surface. Preliminary analysis revealed two distinct layers of haze: One at an altitude of about 50 miles (80km), the other 30 miles (50km) above the surface.
Michael Summers, a New Horizons co-investigator from George Mason University in Fairfax, Virginia, said in a statement that the “hazes detected in this image are a key element in creating the complex hydrocarbon compounds that give Pluto’s surface its reddish hue.”
Models suggest that the hazes form when ultraviolet sunlight breaks apart methane gas, which leads to the accumulation of more complex hydrocarbon gases such as ethylene and acetylene, which have also been discovered at Pluto. As they fall, they condense into ice particles and form the hazes, which are ultimately converted into hydrocarbons that color Pluto’s surface.
Geologic activity previously found only on Earth and Mars
NASA also announced on Friday that new close-up images from the LORRI instrument have shown signs of recent geologic activity in the forms of a sheet of ice that had recently flowed (and which may still be flowing) at the left edge of Pluto’s bright, heart-shaped area.
Specifically, the pictures show signs of exotic flowing ices in the Texas-sized plain informally known as “Sputnik Planum”. The flows resemble activity of Earth-based glaciers, the agency said, and they hoped to find this type of geologic activity, even though they thought it wasn’t likely.
According to NASA, Swirl-shaped patterns of light and dark found in the northern region of Sputnik Planum indicate that a surface layer of exotic ices has flowed around obstacles and into depressions.
Mission co-investigator John Spencer of the Southwest Research Institute said that these types of surfaces had only previously been found “on active worlds like Earth and Mars.” Furthermore, a new set of compositional data from New Horizons’ Ralph instrument has revealed that the center of Sputnik Planum is rich in nitrogen, carbon monoxide, and methane ices.
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Image credit: NASA
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