NASA has detailed fresh discoveries and released the latest batch of images from New Horizons. Sent as the unmanned probe hurtles away from Pluto and out of the Solar System, the new images and readings show a haze that may be the source of Pluto's reddish color and exotic ice that flows like glaciers. The space agency has also shared a spectacular New Horizons flyby simulation video.
Hazy hydrocarbon surprise
One of the biggest of the new discoveries released by the space agency is a dramatic image showing Pluto backlit by the Sun that was taken at about midnight EDT on July 15 at a distance of 1.25 million mi (2 million km) from Pluto – just seven hours after the probe's closest approach – and transmitted on July 23. Aside from being a beautiful shot, the image shows something unexpected – haze rising to 80 mi (130 km) above Pluto’s surface. This is made of two layers, with one ending at 50 mi (80 km) and the other at 30 mi (50 km). Pluto was previously thought too warm to allow hazes to occur higher than 20 mi (30 km).
One important aspect of this haze is that scientists believe it to be the source of the reddish markings found on Pluto's surface, which are the result of tholins. These a group of hydrocarbon molecules produced by the effect of ultraviolet and energetic particles on methane and nitrogen. This breaks down the methane, which recombines to create more complex hydrocarbons, such as ethylene and acetylene that then condense into dark, reddish ice particles on Pluto's surface.
NASA also says that New Horizons' LOng-Range Reconnaissance Imager (LORRI) instrument has uncovered evidence that the exotic nitrogen, carbon monoxide, and methane ices in the informally-named Sputnik Planum region once flowed and may still be flowing like the glaciers on Earth – indicating that Pluto is much more geologically active than was believed before the July 14 flyby.
"At Pluto’s temperatures of minus-390 degrees Fahrenheit, these ices can flow like a glacier," sats 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 appears that ancient, heavily-cratered terrain has been invaded by much newer icy deposits."
New ice mountains
Another fascinating discovery is a new icy mountain range in the Tombaugh Regio (Tombaugh Region). Revealed in a LORRI image taken during the flyby at a distance of 48,000 mi (77,000 km), the range is about as high as the Appalachians on Earth or one-half to one mile (1 to 1.5 km), which makes them shorter than Pluto's previously seen Norgay Montes (Norgay Mountains), which are 68 mi (110 km) to the southeast. The new mountains are believed to be younger than the plains they sit in, dating back billions of years, while the Sputnik Planum is less than 100 million years old.
False color Pluto image
To help provide a better understanding of the New Horizons data, NASA scientists generated this false color image of Pluto. Using four images from the LORRI instrument combined with color data from the Ralph instrument, NASA created an image that reflects the varying compositions that form Pluto's surface. Of particular interest are two bluish-white lobes extending from Sputnik Planum that may be exotic ices flowing from the region.
True color Pluto image
To contrast with the false color image and to show a higher resolution view of Pluto, NASA released this LORRI image. It was taken from a distance of 280,000 mi (450,000 km), which shows features only 1.4 mi (2.2 km) across.
The flyby simulation
One particularly breathtaking release is this simulated flyover of Pluto's Sputnik Planum and the Hillary Montes, which are named after Sir Edmund Hillary, who conquered Mount Everest along with Tsing Norgay (for whom the Norgay Montes are named) in 1953. The flyover animation is based on LORRI images taken from 48,000 mi (77,000 km).
New Horizons is 7.6 million mi (12.2 km) from Pluto and NASA says it is fully operational as it heads into the Kuiper Belt. It will continue to send back data for 16 months.
“We knew that a 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,” says John Grunsfeld, NASA’s associate administrator for the Science Mission Directorate. “With flowing ices, exotic surface chemistry, mountain ranges, and vast haze, Pluto is showing a diversity of planetary geology that is truly thrilling."