Stunning new Pluto pictures are "a scientific bonanza"
Dramatic new photos of Pluto taken by NASA's New Horizons probe during its historic July 14 flyby show multiple haze layers in the dwarf planet's tenuous nitrogen atmosphere, signs of icy fog obscuring the surface and the best views yet of nitrogen ice glaciers creeping into the now-familiar heart-shaped plain known as Sputnik Planum.
The photos, released by NASA Thursday, were snapped at an altitude of about 11,000 miles, just after New Horizons passed behind Pluto. The pictures reveal a stunning backlit crescent showing jumbled ice mountains towering 11,000 feet above the outer edges of Sputnik Planum in a scene that looks strangely similar to arctic settings on Earth.
Thanks to the backlighting from the distant sun, more than a dozen thin haze layers can be seen extending from the surface to an altitude of 60 miles or more. Zoomed-in, close-up views show what appears to be a bank of foggy haze just above the surface, laced with multiple sharp shadows of nearby peaks.
"This image really makes you feel you are there, at Pluto, surveying the landscape for yourself," Alan Stern, the New Horizons principal investigator, said in a NASA web posting. "But this image is also a scientific bonanza, revealing new details about Pluto's atmosphere, mountains, glaciers and plains."
Remarkably, the new pictures indicate the presence of some sort of active cycle reminiscent of Earth's water-based hydrologic cycle. But on Pluto, the cycle is based on the transport of exotic ices and not the water ice found on Earth.
NASA's web posting says "bright areas east of the vast icy plain informally named Sputnik Planum appear to have been blanketed by these ices, which may have evaporated from the surface of Sputnik and then been redeposited to the east."
The photos also show the best views yet of glaciers flowing from the ice-blanketed region back into Sputnik Planum with features "similar to the frozen streams on the margins of ice caps in Greenland and Antarctica."
"We did not expect to find hints of a nitrogen-based glacial cycle on Pluto operating in the frigid conditions of the outer solar system," Alan Howard, a member of the mission's Geology, Geophysics and Imaging team, said in the web posting.
"Driven by dim sunlight, this would be directly comparable to the hydrological cycle that feeds ice caps on Earth, where water is evaporated from the oceans, falls as snow and returns to the seas through glacial flow."
Stern agreed that Pluto is "surprisingly Earth-like in this regard. And no one predicted it."
Due to the vast distances involved, the small size of New Horizons' main antenna and the power of its radio transmitters, only a small fraction of the probe's flyby imagery has been transmitted to Earth. NASA is posting pictures as they are received and analyzed, but it will take more than a year to collect all of the stored data.