Spaceflight Insider

Halo craters on Pluto pose a mystery; NASA media liaison relives the flyby

Pluto New Horizons JHUAPL image posted on SpaceFlight Insider

Photo Credit: NASA / JPL / JHUAPL

Pluto’s surface seems to have an endless array of mysterious features, the latest being craters that appear to be surrounded by bright halos on the far west of New Horizons’ encounter side.

Located in a dark region titled Vega Terra, the craters are clustered together, their bright walls and rims in stark contrast to the area’s terrain.

On the bottom right of the region is its largest haloed crater, measuring approximately 30 miles (50 km) across.

Composition data from New Horizons’ Ralph / Linear Etalon Imaging Spectral Array (LEISA) identifies the bright halos as being methane ice, which is also scattered abundantly in Vega Terra.

Ralph/LEISA imaged the area at a resolution of 1.7 miles (2.7 km) per pixel.

The mission team released two close-up images of the cratered region, the upper one in monochrome and the lower one in false color.

Pluto’s ‘Halo’ Craters

Within Pluto’s informally named Vega Terra region is a field of eye-catching craters that looks like a cluster of bright halos scattered across a dark landscape. Image Credit: NASA/JHU-APL/SwRI

The black and white image is actually a mosaic created from two separate pictures of the same area taken by the Long Range Reconnaissance Imager (LORRI), one in high resolution and the other in low resolution. LORRI captured the high-resolution image, taken at 760 feet (232 meters) per pixel on July 14, 2015, from a distance of 28,800 miles (46,400 km).

That image was overlaid on the low-resolution image, taken at 2,910 feet (889 meters) per pixel, snapped from a distance of 106,700 miles (171,700 km) from the dwarf planet.

In the bottom image, created from Ralph/LEISA data, false color shows the distribution of both methane and water ice. Purple regions indicate methane ice while blue ones, which appear between the craters on the area’s floor, show water ice.

Scientists currently cannot explain why the methane ice is present on the craters’ rims and walls and distributed this way in Vega Terra. They also do not know why similar haloed craters have so far not been found in other regions of Pluto’s surface.

A day after the Vega Terra images were released, Laurie Cantillo, media liaison in NASA’s Office of Communications, published a blog entry providing a first-hand account of the July 14 Pluto flyby from mission headquarters at the Johns Hopkins University Applied Physics Lab in Laurel, Maryland.

Titled “Pluto Flyby: The Story of A Lifetime“, the blog post discussed the July 4 crisis when contact with the spacecraft was temporarily lost and then the elation of scientists, engineers, and writers once the first images of Pluto started arriving.

Cantillo vividly describes how Pluto, with its iconic ‘heart’, became a worldwide media sensation, with stories of the flyby appearing on the front covers of more than 450 newspapers around the world.

With new images and data still being returned practically every week, interest in the mission continues to remain high worldwide, nine months after the flyby, she notes.

New Horizons, launched in January of 2006, has completed its primary mission of flying past Pluto and its fleet of moons and has since moved on to the secondary phase of its missions which includes exploring a portion of the Kuiper Belt.


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.

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