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18.07.2015
The inset images highlight dark streaks of material that were spotted on Pluto by the New Horizons spacecraft. One hypothesis is that the material consists of hydrocarbons that were blown across the surface by winds in Pluto's thin atmosphere. NASA / JHUAPL / SwRI
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Dark streaks on the ice
Some of the images from New Horizons show miles-long streaks of dark material on Pluto's icy plains. Moore said the streaks look similar to the dark wind streaks documented by Mars orbiters.
Moore didn't rule out the possibility that they might be plumes of material ejected from the surface, similar to the geyser plumes spotted by NASA's Voyager probe on Triton, Neptune's largest moon. However, Moore cautioned that the team couldn't confirm the discovery of Plutonian plumes — which was the subject of speculation before the flyby.
He said the "least crazy idea" was that the dark stains were produced when methane frost settles onto the surface, undergoes irradiation and turns into a darker type of hydrocarbon. Winds in the thin Plutonian atmosphere might blow the material around.
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NASA's New Horizons probe captured this pixelated image of Nix, a small moon of Pluto, on July 13 from a distance of about 360,000 miles (590,000 kilometers). Mission scientists believe we are looking at one end of an elongated body about 25 miles (40 kilometers) in diameter. NASA / JHUAPL / SwRI
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Smiley face on Nix?
The New Horizons team also released a picture of one of Pluto's smaller moons, Nix, taken from a distance of about 360,000 miles (590,000 kilometers). The 12-pixel-wide picture doesn't provide much detail, but it does suggest that there's surface variation — in fact, if you squint your eyes, you can almost make out a smiley face.
Previous observations have suggested that Nix is elongated, but in Friday's image, the 25-mile-wide (40-kilometer-wide) moon presents a more circular profile. It's not like the crumpled, potato-like shape of another Plutonian moon, Hydra, as seen in a New Horizons image released earlier this week.
Quelle: NBC
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Potential geysers spotted on Pluto
Today, NASA’s New Horizons team unveiled the latest trove of geological goodies in close-up pictures of the surface of Pluto: hummocky hills that rise up above smooth plains of ice, patches of ice pocked by eroded pits, and troughs that form the boundaries of mysterious polygonal structures. Most tantalizing of all, the team has spotted streaks of material that may have blown downwind from dark spots. Although the team is not yet ready to declare that these spots are geysers shooting plumes above Pluto, scientists say the spots and streaks resemble actively spewing geysers on Neptune’s moon Triton that were discovered in 1989.
The evidence is accumulating that Pluto is an active world, and not only as a place shaped by top-down atmospheric processes of frost and wind and sublimating ice. There also appear to be processes working from the bottom up: forces that lift up water ice mountains the size of the Rocky Mountains and allow them to sit next to smooth plains of ice that, the team suspects, have been resurfaced as recently as within the past 100 million years—or even last week.
“Have a look at the icy frozen plains of Pluto,” said Alan Stern, the mission’s principal investigator at Southwest Research Institute (SwRI) in Boulder, Colorado, as he revealed a glimpse of a region named Sputnik Planum in a press conference today at NASA headquarters. “Who would have expected this kind of complexity?”
The team released the first results from measurements made as the spacecraft passed behind Pluto into its shadow. By measuring the way sunlight was eclipsed around the rim of Pluto, the team was able to analyze its atmosphere—and rule out models showing a turbulent atmosphere in favor of one that is more sluggish. Even with a more stagnant atmosphere, the part of it closest to the surface could still harbor winds blowing at a meter per second or two—enough to move tiny particles of ice around, says Randy Gladstone, a mission co-investigator at SwRI in San Antonio, Texas.
But the pictures, as usual, stole the show. Sputnik Planum is a region along the southern fringe of the left ventricle of the “heart,” now informally called Tombaugh Regio after Pluto’s discoverer. “I’m still having to remind myself to take deep breaths,” says Jeff Moore, a mission co-investigator at NASA’s Ames Research Center in Moffett Field, California. “The landscape is just astoundingly amazing.” To underscore the point, scientists used New Horizons’ terrain measurements to simulate a dramatic flyover video of the area and a nearby ice mountain range called Norgay Montes (see below).
Moore says that one of the few terrains that invites a confident diagnosis are the pitted regions, which form as ice sublimates into the atmosphere. He cannot say whether the hills are features that were pushed up above the surrounding plains, or whether they are composed of tougher materials that resisted erosion as the rest of the region wore down. “They can either be popping up or emerging from an erosion-lowering process,” he says. The polygonal troughs are also mysterious, he says. He doesn’t know whether they result from convection in the interior—the large-scale patterns of heat upwelling in Pluto’s mantle—or from contracting ice, analogously to the way mud cracks form on Earth.
Moore says it’s likely that the Sputnik Planum terrain—which also contains the geyserlike spots—extends all the way up into the left ventricle of the heart. Stern presented chemical evidence that this entire region is enriched in carbon monoxide ice. It could be either a pool of very thick layers of ice that welled up from below, or just a centimeter-thick veneer of carbon monoxide snow from above. Moore says the jury is still out on whether Tombaugh Regio was emplaced from below or shaped from above. Quite possibly, he says, both processes are in play: The terrain may have been deposited in a bout of activity a long time ago, and since been eroded. “It could be there’s a source region there,” Stern says. “It’s a very special place on the planet.”
New Horizons, a spacecraft the size of a baby grand piano, on Tuesday made its closest approach past Pluto, flying within 12,500 kilometers of its surface and making a first-ever reconnaissance of an object in the Kuiper belt, the region of icy worlds beyond Neptune. But images from Pluto are being returned to Earth in a trickle over the course of 16 months, because of the vast distances and the modest power of New Horizon’s radio antenna. NASA Planetary Science Division Director Jim Green says the spacecraft has returned only 1% to 2% of the data so far.
In pictures NASA released on Wednesday, the big surprise was mountains of water ice rising 3500 meters up from strikingly smooth, crater-free surfaces. The lack of craters—also seen on Charon, Pluto’s largest moon—is evidence for youthfulness, and geological activity that could pave over the surfaces in fresh icy materials. This was unexpected, because many thought that the internal heat sources within Pluto and Charon, leftover from their formation in a giant impact billions of years ago, would have dissipated long ago.
Larry Soderblom, a retired scientist from the U.S. Geological Survey in Flagstaff, Arizona, who helped explore Neptune’s moon Triton on NASA’s Voyager mission, is impressed by both the similarities and differences between that world and Pluto. Pluto is the largest Kuiper belt object; Triton is thought to be a captured one. Both harbor smooth surfaces that suggest repaving driven by internal heating. But where that activity on Triton can be driven by the tidal pull of Neptune, scientists are scratching their heads over what could be driving it on Pluto. There are other differences between the worlds, Soderblom says: Triton lacks Pluto’s tall mountains and its rugged, ropy pits. “Everywhere we go, we’re surprised,” he says. “We should know better by now.”
NASA is planning its next press conference on 24 July. After that, image retrievals from New Horizons’ cameras will pause for nearly 2 months while the team focuses on gathering data from its particle and plasma instruments. In August, the team plans to choose between two candidate Kuiper belt objects—far smaller than Pluto—and then steer the spacecraft to an encounter with it in 2019. The $720 million mission is being operated by Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland.
Quelle: AAAS
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Update: 21.07.2015
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New Horizons Captures Two of Pluto's Smaller Moons
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Pluto has five known moons. In order of distance from Pluto they are: Charon, Styx, Nix, Kerberos, and Hydra.
While Pluto’s largest moon Charon has grabbed most of the lunar spotlight, two of Pluto’s smaller and lesser-known satellites are starting to come into focus via new images from the New Horizons spacecraft. Nix and Hydra – the second and third moons to be discovered – are approximately the same size, but their similarity ends there.
New Horizons’ first color image of Pluto’s moon Nix, in which colors have been enhanced, reveals an intriguing region on the jelly bean-shaped satellite, which is estimated to be 26 miles (42 kilometers) long and 22 miles (36 kilometers) wide.
Although the overall surface color of Nix is neutral grey in the image, the newfound region has a distinct red tint. Hints of a bull’s-eye pattern lead scientists to speculate that the reddish region is a crater. “Additional compositional data has already been taken of Nix, but is not yet downlinked. It will tell us why this region is redder than its surroundings,” said mission scientist Carly Howett, Southwest Research Institute, Boulder, Colorado. She added, “This observation is so tantalizing, I’m finding it hard to be patient for more Nix data to be downlinked.”
Meanwhile, the sharpest image yet received from New Horizons of Pluto’s satellite Hydra shows that its irregular shape resembles the state of Michigan. The new image was made by the Long Range Reconnaissance Imager (LORRI) on July 14, 2015 from a distance of 143,000 miles (231,000 kilometers), and shows features as small as 0.7 miles (1.2 kilometers) across. There appear to be at least two large craters, one of which is mostly in shadow. The upper portion looks darker than the rest of Hydra, suggesting a possible difference in surface composition. From this image, mission scientists have estimated that Hydra is 34 miles (55 kilometers) long and 25 miles (40 kilometers) wide. Commented mission science collaborator Ted Stryk of Roane State Community College in Tennessee, “Before last week, Hydra was just a faint point of light, so it's a surreal experience to see it become an actual place, as we see its shape and spot recognizable features on its surface for the first time.”
Images of Pluto’s most recently discovered moons, Styx and Kerberos, are expected to be transmitted to Earth no later than mid-October.
Nix and Hydra were both discovered in 2005 using Hubble Space Telescope data by a research team led by New Horizons project scientist Hal Weaver, Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland. New Horizons’ findings on the surface characteristics and other properties of Nix and Hydra will help scientists understand the origins and subsequent history of Pluto and its moons.
Image Caption: Pluto’s moon Nix (left), shown here in enhanced color as imaged by the New Horizons Ralph instrument, has a reddish spot that has attracted the interest of mission scientists. The data were obtained on the morning of July 14, 2015 and received on the ground on July 18. At the time the observations were taken New Horizons was about 102,000 miles (165,000 km) from Nix. The image shows features as small as approximately 2 miles (3 kilometers) across on Nix, which is estimated to be 26 miles (42 kilometers) long and 22 miles (36 kilometers) wide.
Pluto’s small, irregularly shaped moon Hydra (right) is revealed in this black and white image taken from New Horizons’ LORRI instrument on July 14, 2015 from a distance of about 143,000 miles (231,000 kilometers). Features as small as 0.7 miles (1.2 kilometers) are visible on Hydra, which measures 34 miles (55 kilometers) in length.
Image Credit: NASA/JHUAPL/SWRI
Last Updated: July 21, 2015
Editor: Tricia Talbert
Quelle: NASA
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Update: 9.08.2015
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Das Beste kommt erst noch von der Pluto-Mission
This view of Pluto is dominated by Pluto’s “heart,” a region of icy plains.
Members of the New Horizons team gather around a laptop as they review newly processed images being sent from the New Horizons spacecraft.
Alan Stern, who pushed and promoted a visit to Pluto for more than two decades and led the NASA New Horizons mission that produced the first pictures of the ninth planet last month, was in Tucson this weekend.
He talked about the surprises revealed in just 3 percent of the data gathered by New Horizons in its flyby of Pluto, and the surprises yet to come as the spacecraft slowly downloads its data from more than 3 billion miles away.
That global portrait of the red-tinged planet with its heart-shaped region of icy plains, for instance, will be five times clearer when the tiny spacecraft unloads the rest of its computer storage in the coming months.
Highlights of the interview:
As you waited for New Horizons to signal that it had gathered all the data on its flyby, was there ever a doubt?
There is always some doubt when you’re dealing with the unknown about the things you can’t control. But I knew the spacecraft was rock solid and that the flyby sequence was very well tested, and I was very confident.
You told me earlier this year that you would temporarily name one of the new moons you found “Arizona” to honor the state where Pluto was discovered, but you didn’t find additional moons.
That was one of my biggest surprises after we kept finding moons from the Hubble (Space Telescope). Every time we’d look harder, we’d find another — and then we get out there and the system is clean as a whistle. I lost a big dinner bet over that.
We now know what Pluto looks like. Does the picture get better?
Quite a bit better. Right now the best resolution imagery is 2 kilometers per pixel, more than a mile per pixel.
The best global that we will have will be at about 400 meters per pixel, five times better, and the best regional will get down to 100 meters per pixel and the very best stuff will be 100 meters per pixel, so you could see the football stadium here in town at that resolution.
Talk about the science surprises so far.
The two biggest surprises I believe we’ve found so far are, No. 1: that Pluto is so complex.
Even having worked on this for a long time and expecting it to really knock our socks off, it’s way beyond my expectations and we have a lot of work ahead to understand that geology — all the volatile transport and everything that’s taking place there. I think it pretty much universally surprised people how intricate this small planet is and how complicated it is.
And then the fact that we found areas the size of Texas, specifically Sputnik planum, that have no craters and that must have formed recently in a geologic sense — less than 1 percent of the age of the solar system. They may have been formed 100 years ago for all we know, but certainly less than 100 million years.
That means small planets are capable of generating geologic change billions of years after they have formed. It’s got to be doing it on its own, and we don’t know how to make that work.
That’s going to be a major, lasting contribution of this mission. It’s going to send the geophysicists to the drawing board to figure out how you do that.
When do we see even better pictures of Pluto?
It will probably be a slow reveal. What you really want to make in the end is the best composite of all the imagery. … It’s going to take us a year to do that, beginning in September.
Along the way, we’ll be showing you much more variety than we’ve been able to, at high resolution, and then there will be stages at which our map is twice as good and then four times as good and then even better still.
We’re going to be in the news and that’s a chance to inspire and to teach about science and to interest kids in STEM education, and we’re going to take full advantage of that.
New Horizons may have another mission — visiting another one or two Kuiper Belt objects. Where does that stand?
We have permission to choose the target and to fire the engines to go in that direction. We’re going to do that this year, then apply for funding and NASA will make that decision next year.
You did get to honor Pluto’s discovery in Flagstaff by naming regions for Percival Lowell, who established the observatory there, and Clyde Tombaugh, who discovered Pluto.
I’m glad we could do that. I think we made a lot of people happy.
Frankly, I think what the IAU (International Astronomical Union) did (in classifying Pluto a dwarf planet) disrespected some very important work and diminished the importance of, not just that planet, but the unbelievable accomplishment of Clyde Tombaugh in doing that in an age, by today’s comparison, of Stone-Age technology.
So the biggest and brightest feature on the planet, which we can see from 100 million miles away like a shining beacon, will be forever Tombaugh Regio.
Doesn’t the name have to be ratified by your friends at the International Astronomical Union?
I’m not worried about that. They wouldn’t dare ...
Quelle: Arizona Datly Star
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Update: 11.08.2015
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Atmospheric Escape and Flowing N2 Ice Glaciers – What Resupplies Pluto’s Nitrogen?
Backlit by the sun, Pluto’s atmosphere rings its silhouette like a luminous halo in this image taken by NASA’s New Horizons spacecraft. Image Credit: NASA/JHUAPL/SwRI
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Hi, I’m Kelsi Singer, a postdoctoral researcher at the Southwest Research Institute, working on NASA’s New Horizons mission and specializing in geology and geophysics. One of my areas of expertise is impact cratering. That subject may not seem related to Pluto’s atmosphere or nitrogen at first, but let me tell you about research that New Horizons principal investigator Alan Stern and I conducted and published as a prediction paper before the flyby of Pluto.
New Horizons has returned striking images of both Pluto’s surface and its atmosphere. Pluto’s atmosphere is similar to Earth’s in that it is predominantly composed of nitrogen (N). But Pluto’s atmosphere is ~98% N, while Earth’s is only ~78% N. Pluto’s atmosphere is also considerably thinner than Earth’s with ~10,000 times lower pressure at the surface.
The nitrogen in Pluto’s atmosphere (in the form of N2 gas) is actually flowing away and escaping the planet at an estimated rate of hundreds of tons per hour. We also see what looks like flowing ice on Pluto’s surface in high resolution images made by New Horizons. The water ice (H2O) that we are familiar with on Earth would be completely rigid and stiff at Pluto’s surface temperatures, but ice made out of N2 would be able to flow like a glacier. So where does all of this nitrogen come from?
One possibility we tested was that cometary impactors could be delivering the necessary material. We explored several different ways that impacts from comets could bring nitrogen to the surface and atmosphere of Pluto and resupply the escaping nitrogen:
1) Could comets hitting Pluto directly deliver enough N to Pluto’s surface and atmosphere?
2) Could these comets excavate or expose enough N2 ice from the near-surface layers on Pluto by forming impact craters?
—> The short answer is that none of these cratering effects seem like they could supply enough nitrogen.
In our prediction paper, we suggested the next most likely suspect for supplying this N is heat and geologic activity inside Pluto itself. This activity could process nitrogen out of Pluto’s rocky interior and get it to the surface. We currently have only a tiny fraction of the data back from the New Horizons flyby, but the fact that there are young-looking areas on Pluto hints at relatively recent geologic activity.
Stay tuned as we get more data back from the New Horizons spacecraft over the coming months, which will refine our estimates of Pluto’s atmospheric escape and provide more images of Pluto’s surface to assess the types and timing of geologic activity.
Images by NASA/JHUAPL/SWRI
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Quelle: NASA
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