New Horizons is starting to see Pluto’s geology
As the day on which New Horizons will be making its historic flyby of Pluto draws near, new images from the spacecraft continue to amaze scientists and astronomers the world over. The latest set of images snapped by New Horizons’ Long Range Reconnaissance Imager (LORRI) are showing glimpse of Pluto’s geology like never before.
Snapped by LORRI on the morning of July 9 and received by the mission control on July 10, the new images of Pluto show a great deal of the dwarf planet’s geology including an immense dark band known as the “whale.”
“We’re close enough now that we’re just starting to see Pluto’s geology,” said New Horizons program scientist Curt Niebur, NASA Headquarters in Washington, who’s keenly interested in the gray area just above the whale’s “tail” feature. “It’s a unique transition region with a lot of dynamic processes interacting, which makes it of particular scientific interest.”
The latest images were taken by New Horizons from a distance of 3.3 million miles (5.4 million kilometers), with a resolution of 17 miles (27 kilometers) per pixel.
At this range, Pluto is beginning to reveal the first signs of discrete geologic features. This image views the side of Pluto that always faces its largest moon, Charon, and includes the so-called “tail” of the dark whale-shaped feature along its equator. (The immense, bright feature shaped like a heart had rotated from view when this image was captured.)
New Horizons principal investigator Alan Stern says that among the structures which have been tentatively identified include what appears to be polygonal features; a complex band of terrain stretching east-northeast across the planet, approximately 1,000 miles long; and a complex region where bright terrains meet the dark terrains of the whale.
Just a day before the historic image that revealed Pluto’s geology partially, LORRI had snapped an image of the fascinating pair – Pluto and its moon Charon – with the mission control likening the two icy worlds as pair of figure skaters clasping hands.
From that image it was evident that Pluto is covered in an array of high-contrast bright and dark features while Charon there are relatively less geological variations with only a dark polar region interrupting a generally more uniform light gray terrain.
The reddish materials that color Pluto are absent on Charon. Pluto has a significant atmosphere; Charon does not. On Pluto, exotic ices like frozen nitrogen, methane, and carbon monoxide have been found, while Charon’s surface is made of frozen water and ammonia compounds. The interior of Pluto is mostly rock, while Charon contains equal measures of rock and water ice.
“These two objects have been together for billions of years, in the same orbit, but they are totally different,” said Stern.
Charon is about 750 miles (1200 kilometers) across, about half the diameter of Pluto—making it the solar system’s largest moon relative to its planet. Its smaller size and lower surface contrast have made it harder for New Horizons to capture its surface features from afar, but the latest, closer images of Charon’s surface show intriguing fine details.
Newly revealed are brighter areas on Charon that members of the mission’s Geology, Geophysics and Imaging team (GGI) suspect might be impact craters. If so, the scientists would put them to good use. “If we see impact craters on Charon, it will help us see what’s hidden beneath the surface,” said GGI leader Jeff Moore of NASA’s Ames Research Center. “Large craters can excavate material from several miles down and reveal the composition of the interior.”
In short, said GGI deputy team leader John Spencer of SwRI, “Charon is now emerging as its own world. Its personality is beginning to really reveal itself.”
NASA’s unmanned New Horizons spacecraft is closing in on the Pluto system after a more than nine-year, three-billion-mile journey. On July 14 it will zip past Pluto at 30,800 miles per hour (49,600 kilometers per hour), with a suite of seven science instruments busily gathering data. The mission will complete the initial reconnaissance of the solar system with the first-ever look at the icy dwarf planet.