Little Pluto bigger than scientists thought as flyby looms

July 13, 2015 byMarcia Dunn
This July 11, 2015, image provided by NASA shows Pluto from the New Horizons spacecraft. On Tuesday, July 14, NASA's New Horizons spacecraft will come closest to Pluto. New Horizons has traveled 3 billion miles over 9½ years to get to the historic point. (NASA/JHUAPL/SWRI via AP)

Little Pluto is a little bigger than anyone imagined.

On the eve of NASA's historic flyby of Pluto, scientists announced Monday the New Horizons spacecraft has nailed the size of the faraway icy world.

Measurements by the spacecraft set to sweep past Pluto on Tuesday indicate the diameter of the dwarf planet is 1,473 miles, plus or minus 12 miles. That's about 50 miles bigger than previous estimates in the low range.

Principal scientist Alan Stern said this means Pluto has a lower density than thought, which could mean an icier and less rocky interior.

New Horizons' 3 billion-mile, 9½-year journey from Cape Canaveral, Florida, culminates Tuesday morning when the spacecraft zooms within 7,767 miles of Pluto at 31,000 mph.

Mission managers said there's only one chance in 10,000 something could go wrong, like a debilitating debris strike, this late in the game. But Stern cautioned: "We're flying into the unknown. This is the risk we take with all kinds of exploration."

"It sounds like science fiction, but it's not," Stern said as he opened a news conference at mission headquarters in Maryland. "Tomorrow morning a United States spacecraft will fly by the Pluto system and make history."

Discovered in 1930, Pluto is the last planet in our solar system to be explored. It was a full-fledged planet when New Horizons rocketed away in 2006, only to become demoted to dwarf status later that year.

New Horizons has already beamed back the best-ever images of Pluto and big moon Charon on the far fringes of the solar system.

"The Pluto system is enchanting in its strangeness, its alien beauty," said Stern, a planetary scientist at Southwest Research Institute in Boulder, Colorado.

With the encounter finally at hand, it all seems surreal for the New Horizons team gathered at Johns Hopkins University's Applied Physics Laboratory. The energy there Monday was described as electric.

Project manager Glen Fountain said New Horizons, at long last, is like a freight train barreling down the track, "and you're seeing this light coming at you and you know it's not going to stop, you can't slow it down."

"Of course, the light is Pluto, and we're all excited," Fountain said.

Three new discoveries were revealed Monday, a tantalizing sneak preview as the countdown to closest approach reached the 21-hour mark.

Besides the revised size of Pluto—still a solar system runt, not even one-fifth the size of Earth—scientists have confirmed that Pluto's north pole is indeed icy as had been suspected. It's packed with methane and nitrogen ice.

And traces of Pluto's nitrogen-rich atmosphere have been found farther from the dwarf planet than anticipated. New Horizons detected lost nitrogen nearly a week ago.

As for pictures, the resolution is going to increase dramatically. Until New Horizons, the best pictures of Pluto came from the Hubble Space Telescope. Hubble did its best from Earth orbit, but managed to produce only crude pixelated blobs of the minuscule world.

The New Horizons spacecraft is the size of a baby grand piano with a salad bowl—the dish antenna—on top. It will come closest to Pluto at 7:49 a.m. EDT Tuesday. Thirteen hours later, around 9 p.m. EDT, flight controllers will learn if everything went well. The spacecraft will have sent the confirmation signal 4½ hours earlier; that's the one-way, speed-of-light, data-transit time between New Horizons and Earth.

Stern expects "a little bit of drama" during closest approach, when the spacecraft is out of touch with ground controllers. New Horizons cannot make observations and send back data at the same time, so scientists opted for maximum science during those most critical hours.

Pluto is the largest object in the so-called Kuiper Belt, considered the third zone of the solar system after the inner rocky planets and outer gaseous ones. This unknown territory is a shooting gallery of comets and other small bodies; every time one of these wayward objects smack one of Pluto's five known moons, the ejected material ends up in orbit around Pluto, thus the debris concern. An extension of the $720 million mission, not yet approved, could have New Horizons flying past another much smaller Kuiper Belt object, before departing the solar system.

Stern expects two opportunities to celebrate Tuesday: one at the time of closest approach and the other once confirmation is received that New Horizons stayed safe and accomplished its long-awaited mission.

"There is that element of exploration and there's that small element of danger," he said, "so I think we're all going to breathe the final sigh of relief at 9 p.m. and that's when we can really call it a successful flyby."

Explore further: Scientists get their last look at Pluto's mysterious dark spots

More information: NASA:

Johns Hopkins University:

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1 / 5 (7) Jul 13, 2015
The energy there Monday was described as electric.

I think gravitic would be more appropriate being astronomers would prefer to ignore anything electric.
1.8 / 5 (4) Jul 14, 2015
With all the commo abilities of quantum systems in entanglement...we appear to have found the way around any supposed commo barriers, we need to get a quantum entangled photonic commo system on future probes so that we can have real time control again. First systems will be 'primitive' and not very data rich but would suffice for command and control functiions while the data streams could go the old route until we get better at making these systems more data rich.

This is analogous to the first integrated circuit darlington pair memory systems on 4K dual inline package socketed units for the old microcomputers of the 1980's. Scientists of the time were not sure they would ever make more data rich chips. The old D.I.P.s were an inch or more long by 1 cm wide and 5mm thick for 4K or less data. Now MicroSD cards hold 64 gigabytes of data (64 million times as much) in a package a small fraction of that volume.
1 / 5 (1) Jul 14, 2015
So... Is it back on the list of planets now, or what?
Jul 14, 2015
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5 / 5 (4) Jul 14, 2015
we need to get a quantum entangled photonic commo system on future probes so that we can have real time control again.

Please stop with scientese and learn some real science. Quantum entanglement cannot be used for faster than light control (or any other kind of message passing).

So... Is it back on the list of planets now, or what?

not rated yet Jul 14, 2015
Really, you know this as an undeniable, irrevocable fact AA?

I thought you died from removal of vital organs in a lost wager, right?

How is it being a brainless zombie, may I ask?
5 / 5 (1) Jul 14, 2015
Really, you know this as an undeniable, irrevocable fact AA?

Undeniable? irrevocable? No. But FTL message passing it is in no way supported by current theory AND experiments. There is a reason why it is called "spooky ACTION at a distance" and not "spooky INFORMATION TRANSMISSION at a distance". Think about that.

thought you died from removal of vital organs in a lost wager,

Since you lost it (or better: refused to go ask any scientist and get an opinion that could be quoted) - why should I have a problem?

How is it being a brainless zombie, may I ask?

Dunno. You're the expert. You tell me?
not rated yet Jul 14, 2015
'Action' (spooky or otherwise) does Not involve 'information transmission' .. Right?

As I am an expert on Zombies, I can tell you qualify. You're almost mindless.

Nevertheless, I've seen you in your better days. I'm hoping you get well soon.
not rated yet Jul 14, 2015
Or die. Whatever.
5 / 5 (1) Jul 14, 2015
'Action' (spooky or otherwise) does Not involve 'information transmission' .. Right?

No it does not. That's why this can be used for encyrption but not message transmission (encryption does not constitute classical information transmission). Einstein was very well aware of this distibction and that#s why he called it "action" and not "information transmission".

It's not easy to understand. You have to dig a bit into information theory to figure out the difference between quantum information and classical information and the difference between quantum teleportation (which is possible) and the idea of "classical teleportation" (which is not).

You asked any scientists yet? it's not hard. Just go to any university webpage and grab any email adress of a PhD student, postdoc or prof. When you have a response post it.

We're all (still) waiting.
...or are you that afraid to getting in touch with real scientists?

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