The Amazing Floating Hill-Sized Icebergs of Pluto
Like the icebergs that float in Earth's Arctic Ocean, it seems Pluto has water ice 'hills' that float atop an ocean of frozen nitrogen.
Like the icebergs that float in Earth's Arctic Ocean, it seems Pluto has water ice "hills" that float atop an ocean of frozen nitrogen.
In new images beamed back from NASA's New Horizons mission, which zipped past the dwarf planet on July 14, 2015, glorious detail has been added to Pluto's famous Sputnik Planum, the western half of the heart-shaped Tombaugh Regio feature. Planetary scientists are still poring over the observations, but they've made some interesting early discoveries as to the surprising dynamics underway in Pluto's ice.
Sputnik Planum is known to contain large quantities of nitrogen ice, giving the region a smooth appearance against a "shoreline" of craggy mountains. But just because it's ice, it doesn't mean it's static. The physics of ices in the outer solar system is very different to what we're used to on Earth. This ocean of nitrogen is in motion, albeit extremely slowly. Over millions of years it is believed the ices in Sputnik Planum are cycling - akin to a retro lava lamp - creating a complex pattern of convection cells.
Amidst the "high seas" of nitrogen ice, huge chunks of water ice have been spotted. As water ice is more buoyant than nitrogen ice, the water ice floats in a not-so-unfamiliar fashion to icebergs in our oceans. As such, these New Horizons images are showing a migrational pattern of huge hills of water ice being pulled out into "chains" that collect in groups and drift to the nitrogen ice's convection cell edges.
"The hills are likely fragments of the rugged uplands that have broken away and are being carried by the nitrogen glaciers into Sputnik Planum," writes a NASA New Horizons news update.
In addition, a large feature toward the north edge of Sputnik Planum is a cluster of water icebergs that have apparently "beached" themselves. After floating atop the nitrogen ice, they've hit a shallower portion, becoming grounded and accumulating. This near-40 mile-wide feature has been called "Challenger Colles" by the New Horizons team, honoring the crew of the Space Shuttle Challenger that exploded shortly after lift off 30 years ago.
Chunks of water ice on Pluto ‘float’ in a sea of frozen nitrogen and move over time — another example of Pluto’s fascinating geological activity.
Newly returned pictures taken by NASA’s New Horizons spacecraft are giving scientists -- and the rest of us -- the most detailed views of Pluto’s stunningly diverse landscape. “We continue to be amazed by what we see,” NASA chief scientist John Grunsfeld said in a statement. The latest images form a strip 50 miles wide and were taken when New Horizons was about 15 minutes away from its closest approach to Pluto on July 14.
As NASA’s New Horizons spacecraft raced toward a July 14 close encounter with Pluto, the probe’s telescopic long-range camera got to work on a sequence of pictures that revealed features smaller than half of a city block. Pluto’s surface turned out to be unexpectedly diverse, evidence of a complicated and rich geology. The mosaic pictured here starts about 500 miles northwest of Pluto's smooth Sputnik Planum region and covers the rugged al-Idrisi mountains, the shoreline of Sputnik Planum and its icy plains.
This image has been scaled and rotated, for the full, high-resolution view,
Scientists aren’t sure yet how some of Pluto’s craters came to contain layers, such as the one picture here in the upper right. “Layers in geology usually mean an important change in composition or event, but at the moment New Horizons team members don’t know if they are seeing local, regional or global layering,” NASA said. New Horizons’ Long Range Reconnaissance Imager (LORRI) took a series of images about 15 minutes before the spacecraft’s July 14 close encounter with Pluto. The dark crater at the center of the image is apparently younger than the others because material thrown out by the impact is still visible. Most of the craters are within a 155-mile wide region known as Burney Basin, the outer rim of which appears as a line of hills at the bottom of this image.
New Horizons gathered a 50-mile-wide view of Pluto’s rugged northern hemisphere, including a 1.2-mile high cliff, seen here from the left to the upper right, during a series of pictures taken by the spacecraft’s telescopic Long Range Reconnaissance Imager (LORRI) on July 14. The cliff is part of a canyon system that stretches for hundreds of miles across Pluto’s northern hemisphere. Scientists believe the mountains in the middle are comprised of water ice that has been changed by the motion of nitrogen or other exotic ice glaciers over the eons. At the bottom of the image, which was taken when New Horizons was about 10,000 miles from Pluto, the badlands meet the giant icy plains of Sputnik Planum.
Blocks of ice, upper left, appeared to be jammed together in an area the New Horizon scientists are calling the al-Idrisi mountains. Some of the mountains seem to be coated with a dark material, while others are bright. Scientists think material crushed between the mountains may be from the ice blocks jostling back and forth. The mountains end at the shoreline of a region named Sputnik Planum, which is marked by soft, nitrogen-rich ices that form a nearly flat surface. New Horizon’s Long Range Reconnaissance Imager (LORRI) took a series of images in the span of about one minute at 11:36 Universal Time on July 14, about 15 minutes before the spacecraft’s closest approach.