Weird Woodworm-like Pits on Pluto Reveal Icy Puzzle

Like a woodworm-infested log, new photos from NASA's New Horizons mission of dwarf planet Pluto have revealed a pockmarked terrain that is as puzzling as it is beautiful.

Like a woodworm-infested log, new photos from NASA's New Horizons mission of dwarf planet Pluto have revealed a pockmarked terrain that is as puzzling as it is beautiful.

PHOTOS: New Pluto Pics Show Beautiful, Complex World

Imaged just before the NASA probe made close approach on July 14, this new view of Pluto's icy Sputnik Planum region reveals hundreds of pits, a few hundred meters wide by a few tens of meters deep, swarming across the surface. Composed of ices such as nitrogen, planetary scientists are making an early guess that these features are caused by sublimation, but the alignment and location of the pits are a mystery.

Sublimation occurs when an ice turns directly into a vapor without turning into a liquid - like "dry ice" on Earth (carbon dioxide ice), the ice will change phase into a gas without passing through the liquid phase. As there is little atmospheric pressure on Pluto, sublimation is a dominant process; as the abundant surface ices are heated, they vent gases into the tenuous atmosphere, forming a surprisingly complex interplay between the surface and atmosphere.

NEWS: Pluto has Ice Mountains, Charon is Active

Indeed, the surprising lack of impact craters on Sputnik Planum shows the surface is constantly being refreshed by new ice likely being layered from the atmosphere and these pits are physical evidence of this bizarrely active ice layer.

"Pluto is weird, in a good way," said New Horizons project scientist Hal Weaver, of Johns Hopkins Applied Physics Laboratory in Laurel, Md. "The pits, and the way they're aligned, provide clues about the ice flow and the exchange of volatiles between the surface and atmosphere, and the science team is working hard to understand what physical processes are at play here."

It's hard not to imagine what this landscape would look like if we could stand on the surface of Sputnik Planum. We already know that this region is pretty much flat, but the inclusion of these pits would make it look like an ocean of dramatic sinkholes in the ice stretching to the horizon.

ANALYSIS: New Horizons Returns Photos of Hazy ‘Arctic' Pluto

One of the biggest surprises to come from New Horizons' flyby is the interesting dynamism of Pluto. Considering the tiny world is located in the Kuiper Belt, nearly 50 times further away from the sun than Earth, the fact that there is any activity evident in Pluto's surface is a surprise. But it seems that even in the solar system's hinterland, ancient worlds remain active and just the tiniest trickle of heat from the sun and planetary formation can have dramatic impacts on the geology of these worlds.

A little over 4 short months ago, we had few clues about how dynamic and rich Pluto's surface would be, but already New Horizons has revolutionized our understanding of Pluto and just how active small icy worlds can be.

Source: NASA

This image was taken by the Long Range Reconnaissance Imager (LORRI) on NASA's New Horizons spacecraft shortly before closest approach to Pluto on July 14, 2015; it resolves details as small as 270 yards (250 meters). The scene shown is about 130 miles (210 kilometers) across. The sun illuminates the scene from the left, and north is to the upper left.

New Horizons is a lean, speedy space machine, but mission managers did tuck in nine mementos. Here's a rundown of what’s aboard.

Pluto’s discoverer Clyde Tombaugh died in 1997, a few years before NASA finally committed to send a spacecraft to what was then considered the last unexplored planet in the solar system. Astronomers have since discovered that Pluto resides in a previously unknown region called the Kuiper Belt, with hundreds of thousands of mini-planets and comet-like objects orbiting beyond Neptune. Tombaugh is along in more than spirit. A small container of his ashes is attached to the inside, upper deck of New Horizons, inscribed with the following: "Interned herein are remains of American Clyde W. Tombaugh, discoverer of Pluto and the solar system's ‘third zone’ Adelle and Muron's boy, Patricia's husband, Annette and Alden's father, astronomer, teacher, punster, and friend: Clyde W. Tombaugh."

MORE: From the Start, Pluto was a Puzzle

Even before New Horizons’ launch in January 2006, public outreach was a big part of the mission. Its “Send Your Name to Pluto” campaign resulted in a compact disc containing the names of 434,738 people who signed up for the honors. The disc was mounted to the outside of the spacecraft. (If you signed up, you can search for your certificate at The project was spearheaded by an artist and member of the Carl Sagan team that developed gold-plated phonograph records containing sights and sounds from Earth for the 1970s-era Voyager probes. New Horizons also carries a second CD-ROM with pictures of the New Horizons team members, as well as two U.S. flags.

MORE: New Photos Show A Two-Faced Pluto

In 2004, Florida released its new state quarter, depicting, among other images, a space shuttle and engraved with the words “Gateway to Discovery.” It, along with a quarter from Maryland, were included to note the places where New Horizons departed Earth and where it was manufactured. “We thought it was a cool thing to do. All the states were coming out with new quarters then,” New Horizons lead scientist Alan Stern, with the Southwest Research Institute in Boulder, Colorado, told Discovery News. “We would have flown Colorado too, but it didn’t have a state quarter in time.” With space tight aboard New Horizons and every ounce of weight a factor, the coins doubled as spin-balance weights.

MORE: Student Experiment Will Count Cosmic Particles Around Pluto

In 1991, the U.S. Postal Service issued a postage stamp (it cost 29 cents to mail a letter back then, by the way) with an artist’s rendering of Pluto and the words “Not Yet Explored.” “We thought it would be great to have this stamp fly past Pluto while its message becomes obsolete,” Stern wrote on the project’s website. A petition is underway at to have the USPS issue a new Pluto stamp, now that its old one is obsolete.

ANALYSIS: Apollo 15's Bizarre Contraband Stamp Debacle

As New Horizons was coming together, SpaceShipOne became the first privately funded human spacecraft to travel in space. A trio of suborbital flights, including a test run and two trips to clinch the $10 million Ansari X Prize, gave SpaceShipOne a place in the history books, a spot in the Smithsonian’s National Air and Space Museum and, for a little piece of it anyway, a ride aboard the first spaceship to travel to Pluto. The piece cut from SpaceShipOne is installed on New Horizons’ lower insider deck.

MORE: After Pluto, Where Will NASA's New Horizons Go?