For NASA’s New Horizon spacecraft, it was just 14 minutes of flyby the dwarf planet Pluto but it gave a rare opportunity to take the closest ever pictures of the icy surface that reveals young mountains still rising.
Estimated to be around 11,000 feet (3,500 meters), the mountain range could have formed no longer than 100 million years ago, compared to 4.5 billion of the solar system’s age, said Jeff Moore of NASA’s Ames Research Center in Moffett Field, California.
The mountains cover just one percent of Pluto’s surface and Moore and his colleagues base the youthful age estimate on the lack of craters in this scene. The mountainous region would presumably have been pummeled by space debris for billions of years and would have once been heavily cratered, they said.
“This is one of the youngest surfaces we’ve ever seen in the solar system,” said Moore as Pluto cannot be heated by gravitational interactions with a much larger planetary body as is the case with other planets. He attributed some other process to trigger the mountainous landscape.
“This may cause us to rethink what powers geological activity on many other icy worlds,” said John Spencer of the Southwest Research Institute in Boulder, Colorado, adding that the mountains could have been composed of Pluto’s water-ice “bedrock.”
Although methane and nitrogen ice covers much of the surface of Pluto, these materials are not strong enough to build the mountains. Instead, a stiffer material, most likely water-ice, created the peaks. “At Pluto’s temperatures, water-ice behaves more like rock,” said Bill McKinnon of Washington University, St. Louis.
The close-up image shown in the picture was taken about 1.5 hours before New Horizons closest approach to Pluto, when the craft was 47,800 miles (77,000 km) away from the surface. The image also indicates structures smaller than a mile across.
Images Credit: NASA-JHUAPL-SwRI