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Caption: This patched-together image of Pluto shows New Horizons’ views of the dark, cratered Cthulhu Regio below Sputnik Planum’s bright, left lobe. NASA/JHUAPL/SWRI
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Caption: A large region of jumbled, broken terrain on the northwestern edge of Sputnik Planum (that’s the big heart). NASA/JHUAPL/SWRI
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Caption: Scientists are still working out what causes these enigmatic fields of dark, aligned ridges. If they are dunes, that could mean Pluto has wind. NASA/JHUAPL/SWRI
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Caption: More detail of Pluto’s big heart-shaped ice plain, Sputnik Planum. NASA/JHUAPL/SWRI
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Caption: Two different versions of an image of Pluto’s haze layers, taken by New Horizons as it looked back at Pluto’s dark side. NASA/JHUAPL/SWRI
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Caption: Pluto’s bright, high-altitude atmospheric haze produces a twilight that softly illuminates the surface before sunrise and after sunset. NASA/JHUAPL/SWRI
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Caption: Charon’s surface indicates a surprisingly complex geological history, including tectonic fracturing and mountainous uplift. NASA/JHUAPL/SWRI
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They’re here! Last Saturday, New Horizons started the intensive process of sending data from its July flyby of the Pluto system back to Earth. During its closest approach—about 7,800 miles from Pluto’s surface—the spacecraft collected tens of gigabits of data. That includes photos, spectra, and atmospheric readings. Now that data is coming back bit by bit.
Like, literally. The probe is so far away that it can only send data at a rate of around 1 to 4 kilobits per second. The probe has been sending back lower data-rate information from its energetic particle, solar wind and space dust instruments since late July, but Saturday marked the beginning of a new, year-long download of hi-res images and the like.
That should be plenty of time to clear the hard drives before New Horizons does its next flyby. Did you hear? The little probe will reach Kuiper Belt Object 2014 MU69 in January 2019.
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NASA/JHUAPL/SwRI/Alex Parker
New Horizons has a new destination! The spacecraft, as you might remember, whizzed by the former planet known as Pluto earlier this summer. NASA has now picked its next stop: a small, cold Kuiper Belt object called 2014 MU69 that is nearly a billion miles beyond Pluto.
Although the trip to Pluto has been carefully planned, the trip beyond has been…less so. Kuiper Belt objects at the edge of the solar system are enticing destinations because they’re made up of primitive material largely unchanged since the solar system’s birth 4.6 billion years ago. NASA had been looking for a KBO that New Horizons could visit since 2011. But none of the ground-based telescopes turned up anything that the spacecraft could reach with its remaining fuel.
With time running out, NASA finagled observation time on the Hubble Space Telescope in the summer of 2014. Then, finally, Hubble found five potential targets—eventually narrowed down to two.
2014 MU69 was known as potential target 1, or PT1, because it is easier to reach. But the other option, PT3, looked brighter in the sky, meaning it could be bigger and more interesting. “We have to weigh the risk of something barely reachable and another one that is smaller but easily reachable,” said Hal Weaver, a New Horizons project scientist, back in July. With a multimillion dollar spacecraft on the line, NASA evidently went with the safer bet.
NASA will point New Horizons toward 2014 MU69 with four maneuvers this fall. It’ll reach the target by January 2019. Because of the bureaucratic rules that govern NASA’s budget, though, the official proposal for the 2014 MU69 mission isn’t due until 2016. Of course, it’d be too late to maneuver New Horizons by then.
For now, NASA is also teasing the possibility of an extended mission—even beyond 2014 MU69. Of course, one New Horizons scientist also couldn’t resist a reference to The Martian.
To make this work, we had to channel Mark Watney and “science the $^!§ out of it.” https://t.co/L8KuSK1rQU
— Alex Parker (@Alex_Parker) August 28, 2015
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Pluto has a problem: Its thin, nitrogen atmosphere shouldn’t be there. Ultraviolet rays from the sun should have knocked it away, molecule by molecule, in the dwarf planet’s first few thousand years. Four billion years later, Pluto’s atmosphere is still there, a gauzy interplanetary mystery.
Okay, it’s really scientists who have the problem, because it’s not like there are nitrogen-breathing Plutonians down there pacing worriedly over impending suffocation. Right, NASA? Right?!? No, all worrying has been purely academic, expressed in papers like the one published earlier this month by a pair of New Horizons scientists who examined the trio of prevailing theories behind the atmosphere’s perplexing replenishment.
High noon on Pluto looks like dusk on Earth. But even that small amount of solar energy is enough to turn frozen nitrogen on Pluto’s surface into gas. Once aloft, Pluto’s gravity is too weak to keep the particles from being blown away by ultraviolet radiation. (In case you’re wondering, Earth’s mass is enough to keep its atmosphere mostly safe from getting blown off into space.)
Pluto has been around for about four billion years, and according to the best math, it should have lost about 7,000,000,000,000,000,000,000 grams of nitrogen (give or take a zero) since then. But scientists currently estimate that the planet has about 30,000,000,000,000,000 grams of nitrogen atmosphere, and loses about 1,500,000,000,000 grams each year. “Basically, it would take only a few thousand to tens of thousands of years to lose that atmosphere,” says Kelsi Singer, post-doctoral researcher at the Southwest Research Center and co-author of the paper. Basically, that’s not a very long time.
Considering that Pluto has been around for more than four billion years, the odds are pretty friggin’ slim that humans would meet the dwarf planet during its brief phase of atmosphere-having. No, something is replenishing the supply. Scientists, you got some ‘splaining to do.
There are two basic mechanisms for resupplying Pluto’s atmosphere: “You can either bring stuff in from the outside or bring stuff up from the inside,” Singer ‘splains. Comets are a handy mechanism for both categories, as they can deposit nitrogen when they impact, or punch holes through the surface to expose quantities of the frozen gas. Singer is an impact expert, so she did the calculations for how much nitrogen a comet would shed, or dig up, upon impact. Her co-author Alan Stern, studies atmospheres (among other things) and ran the numbers for gas loss. But even with their most conservative estimates—the maximum number of comets, the deepest of impact craters—nothing from off planet could cover the deficit of nitrogen loss.
Instead, they offer that the nitrogen is being replenished through more conventional geologic activity like cryovolcanism or tectonic action. But nobody yet knows what is behind this geologic churning, as Pluto is too small and too old to be holding much remnant energy from its formation. It’s also too far from any planetary body that would be large enough to tidally churn its innards. Something else inside the dwarf planet was causing exhalations. Does a Great Old One stir under the dark equatorial region, ominously nicknamed Cthulhu Reggio? It would explain the Sleeper of R’lyeh’s long absence…
Perhaps wisely, Singer and Stern do not explore that chilling hypothesis.
The most likely battery for Plutonian heat are huge chunks of uranium or potassium wedged in its rocky core. “Those will emit heat as they break down, and the heat has to go somewhere, so it causes local melting,” says Will Grundy, a planetary scientist, ice expert, and French cheese connoisseur at Lowell Observatory in Arizona.
The authors submitted their paper back in May, just as New Horizons was sending home its first images of Pluto. Since then, the probe’s cornucopia of data has supported Singer and Stern’s geologic hypothesis. “We do seem to be seeing a good deal of recent geologic activity on Pluto, so that’s not a bad sign for our paper,” says Singer. Things will look even better come September and October, when they can make better estimations of the impact rate based on the lossless data showing the dwarf planet’s craters. “We also get data from particle and plasma, that will help us calc the rate of atmospheric escape,” she says.
And every bit that arrives will blow away the mystery of Pluto’s missing molecules.
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Earthlings have a sadly unsophisticated view of ice. Terrestrial types mostly think about it in terms of water ice—solid, cold, slick to the touch as it begins to melt in their warm, fleshy hands. But not Plutonians. If you lived on Pluto, you’d have as many names for ice as the Eskimos have for snow: words for carbon monoxide ice, nitrogen ice, and methane ice, all with different properties.
Today’s photos back from New Horizons put the spotlight on those frozen solids. In this top false color image, you can see just how much compositional variety defines Pluto’s surface—from the bright white of the carbon monoxide ice in the middle of Pluto’s “heart,” now officially called Tombaugh Regio, to the bands of colors likely created by the seasonal transport of ices from equator to pole. The blueish spots might be ices that have traveled from the left lobe of Pluto’s heart.
And then there’s the ice’s geological activity. “Water ice at Pluto’s temperatures won’t move anywhere,” says New Horizons co-investigator Bill McKinnon. “But these ices are geologically soft and malleable, even at Pluto conditions.” In new high-resolution images from the LORRI camera, scientists can see the flowing solids—including nitrogen ice—in the vast Sputnik Planum interacting with towering mountains, flowing between them and even filling in old impact craters.
NASA/JHUAPL/SWRI
“We knew there was nitrogen ice on Pluto, but to see evidence for recent geological activity is simply a dream come true,” says McKinnon.
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Feast your eyes on this one. Photos from New Horizons’ mission to Pluto have dwindled to a trickle, but the team has planted a flag in the sand with this most recent image, taken by the spacecraft after its closest approach to the dwarf planet. “You can only get this image by going to Pluto and looking back,” says principal investigator Alan Stern. Casting a dramatic over-the-shoulder glance toward the sun after it had passed Pluto, this is New Horizons’ way of saying “I was here.”
While Pluto’s backlit silhouette is beautiful, this is more than a simple glamour shot. See that band of light surrounding the rock? That’s Pluto’s atmosphere, and looking closely at its illumination tells New Horizons’ atmospheric team some surprising things about its size and its makeup. “This is the image that almost brought tears to the eyes of the atmospheric scientists on the team,” says co-investigator Michael Summers.
For 25 years, scientists have known that Pluto has an atmosphere. But in this image, the New Horizons team could pull out discrete layers of haze—small particles in the atmosphere, scattering sunlight. First off, the entire haze layer is at least 100 miles high, five times higher than the team predicted. And that layer seems to be broken into layers, one up about 30 miles and the other about 50 miles up.
Those two layers may provide clues about the red color on Pluto’s surface. Atmospheric scientists think that methane in Pluto’s atmosphere gets bombarded by UV light, which helps to form other compounds like ethylene and acetylene that finally end up as red-hued hydrocarbons called tholins. Those heavier particles in the low atmosphere eventually fall to the surface, giving Pluto its distinctive hue. Studying the layers in Pluto’s atmosphere should help explain that chain of reactions better—and the team has a year’s worth of data on the way to help.
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If the first close-up images of Pluto’s mountain ranges sent home by New Horizons seemed a little underwhelming, it might have been because you couldn’t really get a sense for their scale in a two-dimensional photo. Now NASA has released an amazing simulated video of the space probe’s flyover, helping those features pop out like they should.
Those mountain ranges have a name now: Norgay Montes, named after one of the first people to summit Mount Everest, Tenzing Norgay. Some of the peaks seen in this flyover are up to 11,000 feet tall—an impressive stat on its own, but especially so when you consider they’re probably made of ice (the frozen nitrogen and methane that covers most of Pluto’s surface would collapse under themselves at that elevation).
The video continues and transports you to the so-called Sputnik Planum, a vast plain of unexpectedly craterless surface that suggests Pluto is geologically quite young (if you can call 100 million years old young). The plain lies within the region now officially named Tombaugh Regio, after Pluto’s discoverer—but to us, it’ll always be Pluto’s heart.
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NASA/JHUAPL/SWRI
Well hel-lo, Charon. NASA just released the latest photo of Pluto’s largest moon in stunning new detail, and this one’s got a closeup of an unusual beauty mark. To us, it strongly resembles an outie bellybutton. But if you’re not quite seeing it, you could also say it looks like “a large mountain sitting in a moat,” as New Horizons scientist Jeff Moore describes it. And his team has no idea what it is.
The closeup, shown above next to an earlier capture of Charon in its entirety, covers about 240 miles from top to bottom, and boasts some handsome craters as well. New Horizons took this image on Tuesday morning about an hour and a half before its historic closest approach to Pluto—about 49,000 miles away from Charon—and compressed it so the probe could send it more quickly back to Earth. So get ready for even better shots of Charon; the spacecraft is in the process of sending the real-deal, high-resolution images.
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NASA/JHUAPL/SWRI
Today the New Horizons team treated the world to new images of Pluto, Charon, and Hydra, all taken by LORRI, New Horizons’ main imager. But LORRI’s all grey. Still to come are images featuring the full visible light spectrum, plus near infrared from RALPH, the probe’s color and infrared imager.
Nothing new from RALPH just yet, but as a tease of what’s to come, New Horizons’ planetary ice expert Will Grundy, of the Lowell Observatory, showed off some methane readings that were sent over in the probe’s final broadcast before it went dark for its July 14 flyby.
The bright blue, red, and black pixels—overlaid on a LORRI basemap—represent methane ice accumulations. These colors represent data from just three of RALPH’s 256 infrared wavelengths. As such, they don’t say much more than that Pluto has different types of ice. “All I’m showing is the diversity of terrains,” says Grundy.
But there are some interesting clues. For one, Grundy says that the colors in the ice cap look a lot like the colors in the right side of the giant heart—which today New Horizons informally named the Tombaugh Regio after Pluto’s discoverer, Clyde Tombaugh. “The ices do have distinct properties, different melting points,” Grundy said at an earlier conference, speaking more generally about Pluto’s surface.
All vague, all tantalizing, and taken in context with some of the other news revealed today—that Pluto has massive mountains made of water ice and could be geologically active—these slim details hint at big things to come.
Pluto may be cold, small, and far away, but the world is anything but dull.
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Over the course of New Horizons’ nearly decade-long journey to Pluto, mission scientists at NASA, Johns Hopkins, and the Southwest Research Institute have watched the icy rock grow from mere pixels into a real place, with topography and geology and all the things you’d expect from a planet (even though it technically isn’t one).
Today, after the space probe completed its closest approach to Pluto’s system, the New Horizons team released a new image—the most detailed ever—that shows mountains on the dwarf planet’s southeastern hemisphere. NASA’s Goddard Space Flight Center posted this timeline of Pluto photos, making the accomplishments of the New Horizons team that much more visceral. Take it all in.
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NASA/JHUAPL/SWRI
Maybe you still haven’t figured out how to say the name of Pluto’s largest moon. Let me help. It’s pronounced “WOW.”
I don’t want to interrupt your gasping with too many words, but here are some quick stats on the shot.
Draw your eyes to the dark area around the moon’s north pole. “Informally we’ve been referring to that as Mordor,” says Cathy Olkin, one of the mission’s top planetary scientists, to the delight of everyone. Trace your gaze down the right curve until you reach a notch, at about the 2 o’clock spot. That’s a canyon. A big one, about four to six miles deep.
And that’s not all. Move your eyes down and in and follow the huge sash of canyons banding across the planet’s middle. This is about 600 miles across, and according to Olkin could be the result of internal processing. That’s right, active geology.
Just as with similar details on Pluto, the team’s speculations about what is causing this geology are so far guarded and vague.
But what’s certain is that “something is making these two worlds very, very different,” says Alan Stern, the mission’s principal investigator. Pluto is covered in water ice, Charon has massive cliffs. But the shroud of mystery that covers both is being steadily removed.
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Okay, here’s the one you’ve been waiting for: Here is the first true close-up picture of Pluto’s surface, focused on the edge of the southeastern hemisphere. It shows that Pluto has mountains, and that those mountains are made of water ice. And most exciting of all—those mountains might be geologically active.
“The most striking geology is that we haven’t found a single impact crater,” says John Spencer, one of New Horizons’ lead scientists. “That means this is a very young surface.” “Young” being less than 100 million years old.
So what could be driving that geologic activity? There’s no planetary body large enough to be driving tidal energy, so Spencer speculates that the energy could be driven by latent radioactive energy, or a large interior ocean could release energy as it freezes. Or, the planet could be storing energy from its formation through some other, unknown process.
And yeah, about that water. See those mountains? Those are about 11,000 feet tall. Frozen nitrogen and methane would crumble under their own weight at those elevations. And because of Pluto’s mass and size, they can’t be bedrock. The only way to balance that equation is ice.
Stay tuned for more science, more pictures, and more excitement from the Pluto system.
Zoom into Pluto & discover mountains, seen during yesterday’s @NASANewHorizons #PlutoFlyby: http://t.co/6QLXLxiW0o https://t.co/toJQ0j7wB6
— NASA (@NASA) July 15, 2015
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In Greek mythology, the hydra was a many-headed dragon snake with regeneration powers. That’s impressive, but I’m pretty sure that its namesake moon has officially eclipsed its forbearer.
“Pluto and Charon are going to steal the day today, but let’s not forget that Pluto has four small moons as well that we want to collect data on,” says New Horizons project scientist Hal Weaver. “This morning, we got the first really well-resolved images of Hydra.”
Prior to this image, the best pictures of Hydra looked like someone took a quick pass of an eraser over a pencil-drawn period. By comparison, each pixel in the relatively crisp little nugget above represents two miles.
The cool thing about Hydra is how much we have to learn about it. Before today, Hydra was square. Now we can finally see its shape, a wobbly sort of potato-looking thing. We also know its size: 28 by 19 miles across. “New Horizons makes it easy for us,” says Weaver. “Just count the number of pixels across.”
And there’s plenty more to come.
As New Horizons floods its team with data, they will learn more about its composition and will develop clues about its origins. Combined with data from the other four moons and Pluto itself, that data will help scientists pull together an origin story for the tiny planetary system.
So, apologies to the lord of the underworld, his ferryman, his ferryman’s mom, pet dog, and many-headed snake monster, your myths are no match for reality.
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It is less than three hours until New Horizons’ safe and sound message arrives—or doesn’t. Worrier that I am, I’m still worried that the brave little probe might run afoul of a dastardly space pebble. But there’s something else that’s also been nagging me: What if Pluto suddenly disappeared?
It’s a question with long odds—much more improbable than the 1 in 5,000 chance of collision Alan Stern mentioned this morning—and let’s face it, pretty silly. But I still found some experts to scratch my itch.
Specifically, I’m curious about the gravitational effects. Would we feel it on Earth? “If Pluto disappeared, it certainly wouldn’t have an effect on Earth,” says Sarah Hörst, a planetary scientist at Johns Hopkins University. Gravity depends on mass, and the force it exerts decreases over distance. Pluto is too tiny, and too far, to affect Earth. And Mars. And Jupiter. And Saturn, Uranus, and Neptune.
Pluto is so tiny compared to everything else that pretty much only its moons would notice if it disappeared. “Notice” meaning they’d shoot off into space.
In fact, even New Horizons wouldn’t really be affected. “There’s no magnetometer, and we’re not using any forces around the planet to trigger anything on board,” says Alice Bowman, New Horizons’ mission operations manager.
New Horizons’ flyby maneuvers are pre-programmed, so if Pluto suddenly disappeared all it would return are pictures of empty space. And because the light from Pluto would disappear before New Horizons had sent its 4:27pm ET message home, any Earthly telescopes would get the news first.
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The Charon name thing is starting to get to me. Every meeting, press brief, interview I hear the name of Pluto’s largest moon pronounced differently. I swear to Hades, sometimes I hear the same person pronounce it two ways. Granted, I’m jet lagged, sleep deprived, and the coffee in the press room is lukewarm and from Dunkin’ Donuts (what gives, NASA?), but I’m starting to feel like someone is messing with me.
So I started asking people—mostly people wearing black polos emblazoned with the nine-sided New Horizons logo: “How do you pronounce the name of Pluto’s largest moon?” I didn’t get far enough to get meaningful survey results, but I did find out why the results would always be mixed.
That’s because I ran into Will Grundy, one of New Horizons’ co-investigators and an astronomer at Lowell Observatory. “Well, the original Greek way to pronounce it would be Gheghron,” he says, shoving the word out of the back of his throat like it’s a big, fat Klingon loogie. Gross, but makes sense. After all, Charon was the ferryman who brought damned souls across the river Styx into Pluto’s realm. But the astronomer who gave the moon its name didn’t even know about the Greek myth when he picked the name1.
Jim Christy, who discovered the moon in 1978, had promised his wife Charlene he would name the object after her. See, his wife’s name is Charlene, so he took her nickname—Char—and threw an -on in on the end to science things up.
Some of his colleagues had been lobbying to name the moon Persephone (Pluto the god’s abducted queen), so he started doing some research. That’s when he stumbled across the Greek myth, and with that argument in hand the astronomical community informally adopted Charon later that year, and then formally in 1985.
So what’s that got to do with the pronunciation? Most astronomers, says Grundy, pronounce it “Share-on, as a tip of the hat to Jim and his wife.” But then he shrugs and says everybody flops back and forth all the time. “We all say it both ways in a single sentence.”
Really? Guys, that is a hell of a way to come up with nomenclature. Lunacy, even.
1 Update 14:26 ET July 20 2015. This Sky & Telescope article from 2008 has the entire naming episode in full detail.
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What we have so far:
Kar-on
Kare-on
Shar-on
Share-on
Sauron
Cuarón
Sharon
Sharona
Jiff
Your thoughts?
(Thanks for the punchline, Paul Sabourin.)
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Once you have pictures of a never-before-seen-up-close almost-planet, you have to start naming what you see. And according to an image of from the New Horizons press room that our correspondent Nick Stockton tweeted earlier today, the Plutonians have started naming their surroundings…informally.
The names are all related to various mythologies of the underworld, appropriately enough. They also suggest that some of these researchers are pretty darn nerdy—though some of the names seem to have come from votes people submitted online during New Horizons’ flight.
Like, for example, “Cthulu,” the name of an elder god from the fiction of HP Lovecraft. Or what about “Balrog,” the name of the monster that seemingly killed Gandalf the Grey in the Lord of the Rings trilogy? Meng-p’o is the Buddhist goddess of forgetfulness and amnesia—she lives in the underworld. Hun-Came and Vucub-Came are Mayan death gods.
We thought at first that Krun was a reference to a Non-Player Character from the hellfire peninsula in World of Worldcraft, but he’s actually one of five lords of the underworld for the Mandaeans, an ancient religion from the Iraq-Iran region. (His nickname is “Mountain-of-Flesh.”) Ala is an underworld and harvest goddess of the Ibo people of eastern Nigeria.
Pluto might not technically be a planet, but it has some great place-names.
Sorry for potato quality but here are informal names new horizons team has given Pluto’s features #PlutoFlyby pic.twitter.com/y5pNYMFuP6
— Nick Stockton (@StocktonSays) July 14, 2015
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Holy moly what a press conference we just had here at Pluto central. Alan Stern unleashed his science officers with new images and new science, and the first to drop were the highest resolution color pics of Pluto and Charon yet.
Each shows some pretty cool stuff. For Pluto, the biggest revelation is that the big heart is actually two different colors. Those colors (exaggerated for contrast) indicate different geologic, tectonic, or morphologic origins. And the rest of the visible world is a mosaic of patina. “Some regions are relatively ancient, and other places are very young and currently undergoing geologic evolution,” said Jeff Moore, the New Horizons team scientist from NASA Ames who presented the images.
But characteristic of the New Horizons team, Moore was guarded on the details. He said he’s waiting for stereographic data—which will show relief—before speculating any further on what might be happening on the dwarf planet’s surface. For instance, the heart’s left lobe currently looks as smooth as a cherub’s cheek, but some cratering might show up at higher resolutions.
The information from Charon is probably even more surprising. See that big blob of red? That stuff came from Pluto. “Charon does not have an atmosphere that is known so far,” says Will Grundy, a New Horizons team scientist and astronomer at Lowell Observatory. Charon may not have an atmosphere, but Pluto is leaking nitrogen like crazy. And as those nitrogen particles leave Pluto, Grundy says they could be getting dragged into Charon’s gravity. The distribution over the moon would be about even. But while nitrogen particles will burn away on the always-sunny equatorial and midlatitude regions, those that land on the polar night side are in the dark for decades.
If this hypothesis is correct, the chemical processes in the nitrogen would stain the underlying rock red. Grundy says he is waiting to see the other side of Pluto to see if that side is also red. “The prediction should say that the other pole looks really similar.”
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New Horizon’s latest of Pluto, at 1024px. NASA/JHAPL/SWRI
Here is New Horizons’ newest image of Pluto, sent from the planet yesterday and released early this morning. Each pixel represents 4 kilometers, and the image is 1000 times the resolution of anything from Hubble.
The image is oriented with Pluto’s north at the top. The dark regions (not shadowed) are the planet’s equator, which is about 2/3rds the diameter of Earth’s moon. The photo shows a lot of detail, but New Horizons’ scientists are cagey about what it all means. There are features indicating impacts, freeze/thaw surface activity and “maybe even tectonic activity indicating internal activity in the past, possibly the present,” says Alan Stern, New Horizons’ principal investigator.
And that’s only a sliver of the information to come. Stereographics will give measurable imagery of topographic relief. Compositional spectrography and plasma readings will show atmospheric activity. Thermal maps are coming. Full color photos.
And all of the above—and so much more—for the moons Charon, Hydra, Styx, Nix, and Kerberos. “By tomorrow, we’ll have images at 10 times the resolution of this image,” says Stern. We’ll be standing by, Alan.
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In the image NASA released of Charon yesterday, astronomers pointed out a collection of vaguely-defined features on the surface of Pluto’s biggest moon. Now, with this latest capture, the New Horizons team has confirmed that the big dent in the icy rock’s surface is in fact an impact crater, surrounded by a couple of deep canyons—one larger than Earth’s Grand Canyon.
Get ready for even more detailed images of Charon and its orbital buddy, Pluto, tomorrow morning when New Horizons makes its closest approach to the system. Geologists will be especially interested to take a closer look at the dark spot on the moon’s northern pole, and the rays of material you can see spraying out from the edges of the crater.
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Tomorrow, when New Horizons makes its historic flyby of Pluto, it will be focusing in on just one face of the dwarf planet. In this latest photo captured by the space probe’s black-and-white LORRI camera, you can see that face—defined by a large, bright heart-shaped feature—beginning to rotate into view.
Only the top half of the heart is visible on the left side of this image, but come tomorrow, New Horizons will capture the valentine in full. (Viewers will have to wait up to a day and a half to actually see the image, since the probe will be too busy collecting data to send it back to Earth immediately.)
Rotating out of view, on the other hand, will be a number of other interesting geological details. The last good look New Horizons got of Pluto’s far side came in on Saturday. And this image is the best astronomers will get of the bullseye-shaped feature (to the right) that might be an impact crater. Without better images, the New Horizons team may never know for sure.
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Nobody is going to see New Horizons fly through the Pluto system. At least, not in real time. But thanks to the power of planetary physics you can watch the space probe pass by on your computer right now. NASA’s awesome visualization team has loaded the flight plan into their Eyes On The Solar System app.
The video above shows 8 hours of the flyby, speeding by at 10 minutes per second. The inset window shows what New Horizons’ suite of instruments see (and which instruments are currently active). And those images are updated as new data comes in.
“That is the best map of Pluto, and if they release another one tonight we’ll update it immediately,” says Doug Ellison, a NASA visualization producer. Like the rest of us, he’s really anticipating that new imagery. “It will be nice to put a map on Charon, it always sucks to have these gray potatoes in space.”
But if you’re really antsy for some real time communications, Ellison recommends you fire up DSN Now. This tool shows active communications from all NASA spacecraft. No need to burn your retinas waiting for New Horizons to perk up. The first communications post-flyby are scheduled to arrive at 9:07pm ET on July 14.
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At a press conference, New Horizons’ top dog Alan Stern just announced that his team has calculated Pluto’s most accurate diameter yet: about 1,473 miles from one end to the other, give or take 12 miles.1 You’d think this would be something NASA had nailed down by now, but it’s impossible to measure Pluto’s size without also knowing its distance from Earth.
That’s right: New Horizons is literally aiming for the unknown. The reason nobody knows Pluto’s exact location is because humans have only known about the planet for 85 years, which is about a third of the time it takes for Pluto to orbit the sun. The uncertainty is relatively small, but it affects all kinds of things.
Like the flight plan as New Horizons passes through the Pluto system. On Tuesday, New Horizons is programmed to rotate and focus its instruments on each of the dwarf planet’s moons in turn, and on the planet itself. If NASA’s estimate of Pluto’s distance is too far off, New Horizons will aim at blank spots in the sky.
Nobody here thinks there’s a huge possibility of missing the system completely, but some actually want the estimates to be a bit off. “Currently, as Charon rises from behind Pluto the camera is still looking at Pluto,” says Doug Ellison, a NASA visualization producer. On the Eyes On Solar System app, he showed me that if Pluto is a little bit closer than the scientists think, New Horizons will be perfectly placed to capture Charon rising behind it. “You hope for a little bit of uncertainty, because then you get that perfect Kodak moment,” he says.
This latest size estimate is slightly larger than what scientists had believed before, and it changes some other calculations. “It’s less dense, so that raises the question of the amount of ice in the interior,” says Stern. That’s because while Pluto’s size was up in the air, scientists have known the planet’s mass for a long time. A larger planet would mean less rock, more ice.
Ironically, scientists won’t get their best size and distance estimates until New Horizons passes through the system.
1UPDATE 1:18 ET 07/14/15: This story was updated to correct Pluto’s diameter.
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Tomorrow, July 14 at 7:49:58 AM Eastern time, New Horizons will pass closest to Pluto. And it will gather its juiciest science during the hours surrounding the fly by.
Or everything could go horribly wrong.
“The most dangerous time for a collision is when you pass through the plane of Pluto’s equator and when you pass all the other satellites,” says Hal Weaver, the mission’s project scientist. But the danger won’t come from one of Pluto’s five (and counting) moons, it’ll be from bits of dust and rock caught in the planet’s gravity.
At 31,000 mph even a glancing blow from a mote of dust could send New Horizons into a tumble, interrupting its most scientifically productive moments. “But anything that sends it into a tumble could also destroy it,” says Chris Hersman, New Horizons’ system engineer. The most vulnerable spot is dead center, where the craft’s propellant is stored. In space, no one can hear you kabloom.
Neither will anyone on Earth. With all sensors trained on Pluto, New Horizons won’t phone home for 21 straight hours. How will radio silence affect the mood in mission control? Many scientists here admit to some amount of anxiety—and to soothing it with suspicious rituals.
But rather than the sound of wind being sucked through a roomful of teeth, 7:50 AM will probably be filled with hoots, hollers, and hands slapping together. “I think it’s going to be pretty wild,” says Alan Stern, New Horizons principal investigator. Everything may have gone wrong, but that won’t stop the New Horizons team, friends, and family from celebrating 3 billion miles and nine and a half years of collision-free space travel.
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NASA/JHUAPL/SWRI
Let’s all take a second to appreciate the fact that this newest photo of Pluto was taken more than 1 million miles away from the icy dwarf planet. That’s how far away New Horizons will be tonight at 11:23 PM EST, on its way to an historic flyby on Tuesday morning.
You might be fooled into thinking Pluto and Charon look really similar, comparing this photo to the latest images of the big moon in the post below. But keep in mind that these images are uncolored, taken by New Horizons’ black-and-white LORRI camera. Once the team has the chance to add in color data from the Ralph camera, the differences between the planet and its moon become clear: Pluto is reddish-orange (not blue, like you might have thought), and Charon is more muted gray.
What’s really cool about these two is they are the only known planet/moon pair with a similar origin to Earth and its Moon. “This is the only other example of a giant impact planetary system,” says Alan Stern, New Horizons’ principal investigator. Of course the difference between the Earth system and the Pluto system being that the latter has many other moons in addition to Charon.
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