New Pluto images reveal stunningly diverse terrains, atmosphere
NASA’s New Horizons has sent back the first in its yearlong downlink of high-resolution images and data from its July 14, 2015, flyby of Pluto. The data, sent from Sept. 5 to 7, revealed a stunning diversity of terrains and a many-layered atmosphere that are leaving scientists in awe.
With resolutions of up to 440 yards (400 meters) per pixel, the new images show Pluto to have a host of different terrains. These include nitrogen ice that appears to have flowed out of mountains and onto plains, and networks of valleys that might have formed by flowing surface material. They also show features that seem to be dark, wind-blown dunes, and disrupted mountainous areas that resemble those on Jupiter’s moon Europa.
By using these latest images, the New Horizons team created a mosaic depicting what observers would see from about 1,100 miles (1,800 km) above the region near Pluto’s equator.
The northeastern section of the mosaic shows the cratered, dark region dubbed Cthulhu Regio and the adjacent smooth icy terrain in the section of the heart-shaped plain known as Sputnik Planum.
The mosaic covers a terrain 1,100 miles (1,800 km) wide with images taken by New Horizons at a distance of 50,000 miles (80,000 km) on July 14. Its smallest visible features have a size of 0.5 miles (0.8 kilometers).
Although members of the New Horizons team knew Pluto’s surface is complex, almost nothing could have prepared them for the depth of complexity the images show.
“Pluto is showing us a diversity of landforms and complexity of processes that rival anything we’ve seen in the Solar System,” Principal Investigator Alan Stern stated. “If an artist had painted this Pluto before our flyby, I probably would have called it over the top – but that’s what is actually there.”
William McKinnon, deputy leader of the mission’s Geology, Geophysics and Imaging (GGI) team, expressed surprise at the possibility of dunes existing on Pluto because the small planet has such a thin atmosphere.
“Either Pluto had a thicker atmosphere in the past, or some process we haven’t figured out is at work. It’s a head-scratcher,” he said.
Interestingly, some of the oldest terrains on Pluto, which are heavily cratered, borders the youngest terrain, which is smooth and craterless.
GGI team leader Jeff Moore described Pluto’s surface as “every bit as complex as that of Mars. The randomly jumbled mountains might be huge blocks of hard water ice floating within a vast, denser, softer deposit of frozen nitrogen within the region informally named Sputnik Planum.”
While Sputnik Planum was one of the first areas of Pluto to be imaged, the new photos represent the first time it is being seen in complete detail.
Mission scientists are equally awed by Pluto’s atmospheric haze, which the latest images reveal to have many more layers than initially thought.
The haze produces a twilight effect that provides soft illumination of the planet’s night side, a boon no one expected.
“This bonus twilight view is a wonderful gift that Pluto has handed to us,” said GGI deputy leader John Spencer. “Now we can study geology in terrain that we never expected to see.”
By brightening images taken near Pluto’s terminator before sunrise and after sunset, mission team members successfully teased out details of the rugged region on the night side.
The newly-released high-resolution images include sharper views of Pluto’s moon Charon.
New Horizons took an image of Charon from a distance of 290,000 miles (470,000 kilometers), approximately ten hours before the spacecraft’s closest approach to Pluto. It reveals evidence of tectonic fracturing, mountains surrounded by sunken terraces on the moon’s right side, smooth fractured plains on the lower right, and old, cratered areas in the upper left and center.
Charon’s surface has bright and dark crater rays as well as the dark, reddish polar region, which is surrounded by some material of a much lighter contrast.
Scientists think the pole is covered by deposits of dark material that may be coming off of Pluto’s atmosphere.
Features as small as 2.9 miles (4.6 kilometers) are visible in the images, which are significantly better than those released on July 15.
The complexity of Charon’s surface features suggests the large moon experienced a “tortured” geological past.
All of these images are sharper than the initial ones sent back in July because they are “lossless”, which means they were created using a form of data compression capable of reconstructing the original images from compressed ones.
Downlinks of data will continue over the next year, with images designated by the mission team as “high priority” sent back first.
Approximately 50 gigabits of data from the flyby are stored on the spacecraft, which is now more than three billion miles (five billion km) from Earth and approximately 43 million miles (69 million km) from Pluto.
The mission team plans to download new images every Friday and post them at New Horizons’ Science Photos.
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.