New Horizons reveals new Pluto mysteries

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Annotated view of a portion of Pluto’s Sputnik Planum(Credit: NASA/JHUAPL/SWRI)

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NASA has released more findings from the New Horizons Pluto probe; revealing new discoveries and mysteries about the dwarf planet and its moons. The images and instrument readings taken before and during the unmanned spacecraft's flyby on July 14 show a planet that is more active than previously expected, with some of the youngest features in the Solar System.

The centerpiece of the new findings is an image taken on July 14 at a distance of 48,000 mi (77,000 km) using New Horizon's Long Range Reconnaissance Imager (LORRI) that shows a plain of carbon monoxide ice that already has scientists scratching their heads. Known informally as the Sputnik Planum (Sputnik Plain), the craterless plain is located in the equally informal Tombaugh Regio (Tombaugh Region); the vast heart-shaped feature north of the Plutonian ice mountains that's named after Clyde Tombaugh, who discovered Pluto in 1930.

The plain resembles mud flats on Earth and consists of irregularly-shaped segments about 12 mi (20 km) across that are bordered by narrow troughs; some of which have darker material inside them. There are also groups of mounds and fields of small pits that may have been formed by sublimation.

Carbon monoxide ice region on Pluto(Credit: NASA/JHUAPL/SWRI)

According to NASA, this region is only a 100 million years old, as is indicated by the lack of impact craters, and may have formed according to one of two working hypotheses. One is that the segments may have been produced by the icy surface contracting and cracking, as when a mud puddle dries in the sun. The other is that the plain is subject to convection with relatively warm, though still frozen, carbon monoxide, methane, and nitrogen circulating to the surface – indicating that there is enough heat inside Pluto to support such a mechanism.

Pluto's atmosphere

During the flyby, New Horizons took a close look at the extremely tenuous Plutonian atmosphere; taking remote measurements of altitudes up to 1,000 mi (1,600 km) above the surface. The nitrogen-rich atmosphere turns out to extend far into space and the probe detected cold, dense ionized gas tens of thousands of miles from the planet. Scientists are particularly interested in Pluto because the way that the solar winds are stripping away the atmosphere is similar to how it's believed the early atmosphere of Earth was thinned out after it was formed.

Pluto and Charon

Another image that NASA released was a higher resolution composite of Pluto and its largest moon Charon that was made of images taken on July 13 and 14. The bodies were tweaked so that the color, relative reflectivity, size, separation, and orientations are realistic.

Charon

An image taken by LORRI at 6:30 am EDT on July 14 shows an area of the moon Charon about 240 mi (390 km) long showing a depression with a peak in the middle.

"The most intriguing feature is a large mountain sitting in a moat," says Jeff Moore, leader of the New Horizons’ Geology, Geophysics and Imaging team. "This is a feature that has geologists stunned and stumped."

Nix

Smaller moons also got a look in as NASA released a LORRI picture of the moon Nix taken on July 13 from a distance of 360,000 mi (590,000 km). It shows an end-on view of the elongated satellite about 25 mi (40 km) in diameter.

NASA says that the images that have been sent back so far have undergone data compression, so many features have a blocky appearance. When higher-resolution and stereo images now in New Horizons' memory are returned, scientists should have a better understanding of Pluto's mysteries.

New Horizons was launched on January 19, 2006, from Launch Complex 41 at Cape Canaveral Air Force Station, Florida atop a Lockheed Martin Atlas V-551 rocket. It's the fastest spacecraft ever launched, reaching the distance of lunar orbit in only nine hours.

After a February 2007 gravity assist from the planet Jupiter, it reached a speed of 83,600 km/h (52,000 mph) relative to the Sun. On July 14 this year, following a nine and a half year voyage through deep space, it passed Pluto at a distance of 7,750 mi (12,500 km) and a speed of 14 km/sec (31,000 mph), making it the final classical planet to be visited by a spacecraft.

"With the flyby in the rearview mirror, a decade-long journey to Pluto is over – but the science payoff is only beginning,” says Jim Green, NASA Director of Planetary Science. "Data from New Horizons will continue to fuel discovery for years to come.”

The video below shows the location of the carbon monoxide ice plain.

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