Young at Heart: Pluto's Ice Only 10 Million Years Old
Pictures are still filtering back from NASA's New Horizons close-up of Pluto last year and one of the biggest surprises so far comes from the region informally known as Sputnik Planum.
Pictures are still filtering back from NASA's New Horizons close-up of Pluto last year and one of the biggest surprises so far comes from the region informally known as Sputnik Planum. There's a lack of craters on its surface, making it a unique area on Pluto and a rare spot in the solar system - it turns out it could be very young terrain indeed.
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"What I did was take the pictures that we have seen - the amazing pictures! - and calculate, based on Pluto's orbital environment, what the impact rate and therefore the surface age of Sputnik Planum must be," wrote planetary scientist David Trilling in an email to Discovery News.
"There have been lots of press releases describing various aspects of Sputnik Planum, but, as far as I know, this is the first time that the age estimate of 10 million years or younger appears in the peer-reviewed literature," added Trilling, an assistant professor of physics and astronomy at Northern Arizona University.
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Trilling's study, which is in press at PLOS One, mentions three ways the resurfacing could take place:
Nitrogen ice on the surface could be "relaxing" if it is viscous, getting rid of any craters created by meteroids.
Ice on the bottom could be rising up and replacing ice at the top, The ice could be partially melted at its bottom and from time to time, erupt on to the surface as cryo-lava.
As for where the meteorites are coming from, Trilling points out that Pluto is in a zone filled with smaller Kuiper Belt objects. From time to time, these small bodies crash into Pluto. Trilling's math shows that this happens roughly every 10 million years, which would explain why Sputnik Planum appears so young.
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Trilling's research is mostly focused on near-Earth asteroids, but Pluto caught his attention not only because of the "astounding" images, but also the lack of craters. He's also hopeful that New Horizons will be funded to look at another Kuiper Belt object up close in 2018. If that happens, Trilling will be on the lookout for more "crater-free patches" to nail down more information about the solar system's evolution.
This high-resolution image from New Horizons shows the “shoreline” of Sputnik Planum on Pluto.
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.
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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.
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