New Pluto images reveal stunningly diverse terrains, atmosphere

This synthetic perspective view of Pluto, based on the latest high-resolution images to be downlinked from NASA’s New Horizons spacecraft, shows what you would see if you were approximately 1,100 miles (1,800 kilometers) above Pluto’s equatorial area, looking northeast over the dark, cratered, informally named Cthulhu Regio toward the bright, smooth, expanse of icy plains informally called Sputnik Planum. The entire expanse of terrain seen in this image is 1,100 miles (1,800 kilometers) across. The images were taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). (Click to enlarge.) Image & Credit: NASA/JHU-APL/SwRI

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.

Mosaic of high-resolution images of Pluto, transmitted by NASA’s New Horizons spacecraft from Sept. 5 to 7, 2015. The image is dominated by the informally-named icy plain Sputnik Planum, the smooth, bright region across the center. This image also features a tremendous variety of other landscapes surrounding Sputnik. The smallest visible features are 0.5 miles (0.8 kilometers) in size, and the mosaic covers a region roughly 1,000 miles (1,600 kilometers) wide. The image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). The two white rectangles show the locations of the two closeup views by New Horizons, released separately. (Click to enlarge.) Image & Caption Credit: NASA/JHU-APL/SwRI

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.

Two different versions of an image of Pluto’s haze layers, taken by New Horizons as it looked back at Pluto’s dark side nearly 16 hours after close approach, from a distance of 480,000 miles (770,000 kilometers), at a phase angle of 166 degrees. Pluto’s north is at the top, and the Sun illuminates Pluto from the upper right. These images are much higher quality than the digitally compressed images of Pluto’s haze downlinked and released shortly after the July 14 encounter, and allow many new details to be seen. The left version has had only minor processing, while the right version has been specially processed to reveal a large number of discrete haze layers in the atmosphere. In the left version, faint surface details on the narrow sunlit crescent are seen through the haze in the upper right of Pluto’s disk, and subtle parallel streaks in the haze may be crepuscular rays- shadows cast on the haze by topography such as mountain ranges on Pluto, similar to the rays sometimes seen in the sky after the Sun sets behind mountains on Earth. Image & Caption Credit: NASA/JHU-APL/SwRI

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.

This image of Pluto from NASA’s New Horizons spacecraft, processed in two different ways, shows how Pluto’s bright, high-altitude atmospheric haze produces a twilight that softly illuminates the surface before sunrise and after sunset, allowing the sensitive cameras on New Horizons to see details in nighttime regions that would otherwise be invisible. The right-hand version of the image has been greatly brightened to bring out faint details of rugged haze-lit topography beyond Pluto’s terminator, which is the line separating day and night. The image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). Image & Caption Credit: NASA/JHU-APL/SwRI

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.

This image of Pluto’s largest moon Charon, taken by NASA’s New Horizons spacecraft 10 hours before its closest approach to Pluto on July 14, 2015, from a distance of 290,000 miles (470,000 kilometers), is a recently downlinked, much higher quality version of a Charon image released on July 15. Charon, which is 750 miles (1,200 kilometers) in diameter, displays a surprisingly complex geological history, including tectonic fracturing; relatively smooth, fractured plains in the lower right; several enigmatic mountains surrounded by sunken terrain features on the right side; and heavily cratered regions in the center and upper left portion of the disk. There are also complex reflectivity patterns on Charon’s surface, including bright and dark crater rays, and the conspicuous dark north polar region at the top of the image. The smallest visible features are 2.9 miles 4.6 kilometers) in size. Image & Caption Credit: NASA/JHU-APL/SwRI

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.

Tagged: Alan Stern Charon Lead Stories New Horizons Pluto Solar System

Laurel Kornfeld

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.