Even at Pluto’s estimated surface temperature of around -380 F, nitrogen ice can creep across the surface of the planet’s icy plain, which has been informally named “Sputnik Planum,” located in Pluto’s heart, the “Tombaugh Regio.”
“There’s nothing implausible about nitrogen glacial flow,” said William McKinnon, a New Horizons co-investigator from Washington Univ. in St. Louis. The movement “is driven from the heat that is leaking out of the interior of Pluto.”
McKinnon, along with colleagues from the New Horizons mission, participated in a NASA News Conference on Friday, updating the public on the recent images and information available from the New Horizons spacecraft.
“We knew the mission to Pluto would bring some surprises, and now—10 days after closest approach—we can say that our expectation has been more than surpassed,” said John Grunsfeld, NASA’s associate administrator for the Science Missions Directorate. “With flowing ices, exotic surface chemistry, mountain ranges and vast haze, Pluto is showing a diversity of planetary geology that is truly thrilling.”
McKinnon estimated the “Sputnik Planum,” which lies within the western half of Pluto’s heart, to be around the size of Texas.
“This is northern boundary … basically this is about 250 miles across,” he said, showing of photo of rugged terrain with a cliff boundary along the exterior of “Sputnik Planum” with graphic arrows pointing to indications of nitrogen ice flow. “We interpret them to be just like glacial flow on Earth.”
He described the ices as geographically soft and malleable. A portion of the photo showed what appeared to be a crater in the rugged terrain filled with ice, possibly filling in through a breach in the cliff area, he speculated.
McKinnon showed a series of images of the plain’s south side, which neighbors a heavily cratered area informally referred to as “Cthulhu Regio.” He described the region as ancient and black. In the same photograph, one could see two of Pluto’s mountain ranges, the “Norgay Montes” and the “Hillary Montes.”
“There’s a whole lot more that we’re going to learn about Pluto and its moon”, Charon, in the future, he said.
Alan Stern, principal investigator for New Horizons at the Southwest Research Institute in Colorado, said about 95% of the data collected by New Horizons has yet to be sent to Earth. He said Friday’s images will be some of the last seen until mid-September, as the focus will now be on transmitting engineering data from the Pluto flyby. “We’ve never been to a double planet system before and it’s really turning out to be a scientific wonderland,” he said.
Michael Summers, a New Horizons co-investigator at George Mason Univ., spoke about the newly discovered haze, which extends at least 100 miles above Pluto’s surface.
“The hazes detected in this image are a key element in creating the complex hydrocarbon compounds that give Pluto’s surface its reddish hue,” said Summers.
According to NASA, the belief is that the hazes form when ultraviolet sunlight breaks up methane gas particles, a hydrocarbon in Pluto’s atmosphere. This triggers buildup of complex hydrocarbon gases, such as ethylene and acetylene. As the hydrocarbons fall to colder parts of the atmosphere, they condense into ice particles, the source of the hazes. “Ultraviolet sunlight chemically converts hazes into tholins, the dark hydrocarbons that color Pluto’s surface,” according to NASA.
Previously, scientists believed temperatures would be too warm for hazes at altitudes higher than 20 miles, according to NASA.
One of the images shown at the news update was of an occultation New Horizons took on the dark side of the planet. The image shows Pluto as a silhouette, a hazy rim of sunlight surrounds the black orb.
New Horizons is currently around 7.6 million miles beyond Pluto, and is barreling deeper into the Kuiper Belt.
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