Washington DC: NASA’s New Horizons mission has made surprising new discovery, and found haze and flowing ice on Pluto. John Grunsfeld, NASA’s associate administrator for the Science Mission Directorate said that with flowing ices, exotic surface chemistry, mountain ranges, and vast haze, Pluto was showing a diversity of planetary geology that was 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).
The hazes detected 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, 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.
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.
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. In the southernmost region of the heart, adjacent to the dark equatorial region, it appeared that ancient, heavily-cratered terrain has been invaded by much newer icy deposits.
The New Horizons mission will continue to send data stored in its onboard recorders back to Earth through late 2016. The spacecraft currently is 12.2 million kilometers beyond Pluto, healthy and flying deeper into the Kuiper Belt.
