With less than two weeks to go before its historic flyby, the Ralph instrument aboard the New Horizons spacecraft has confirmed the presence of frozen methane on Pluto—something scientists first detected as far back as 1976.

Above: A raw, unprocessed image of Pluto as seen by New Horizons’s LORRI on June 29 at a distance of 18.2 million kilometers

Methane, or CH4, is a colorless, odorless gas that’s present in Earth’s atmosphere and subsurface. Some of our methane comes from abiogenic processes, like volcanism, but the vast majority of it is produced by organisms. The methane on Pluto, on the other hand, has more ancient roots. It is a chemical remnant of the solar nebula from which our Solar System formed some 4.5 billion years ago.

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Methane was first detected on Pluto back in the 1970s by New Horizons team member Dale Cruikshank, who now works out of NASA’s Ames Research Center in Mountain View, California. Scientists are excited about the confirmation, which was made by the Ralph instrument’s infrared spectrometer; as more data comes in from New Horizons, the team is hoping to discover differences in the presence of methane ice across different regions of the dwarf planet.

In related news, NASA released its latest time-lapse of the Pluto-Charon system as New Horizons draws nearer.

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NASA explains:

This time-lapse approach movie was made from images from the Long Range Reconnaissance Imager (LORRI) camera aboard New Horizons spacecraft taken between May 28 and June 25, 2015. During that time the spacecraft distance to Pluto decreased almost threefold, from about 35 million miles to 14 million miles (56 million kilometers to 22 million kilometers). The images show Pluto and its largest moon, Charon, growing in apparent size as New Horizons closes in. As it rotates, Pluto displays a strongly contrasting surface dominated by a bright northern hemisphere, with a discontinuous band of darker material running along the equator. Charon has a dark polar region, and there are indications of brightness variations at lower latitudes.

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The New Horizons team is also practicing for the painfully short flyby, which is scheduled for July 14. They’re hoping to use the Alice instrument to scan Pluto’s atmosphere during sunset and sunrise to learn more about its composition.

“It will be as if Pluto were illuminated from behind by a trillion-watt light bulb,” noted Randy Gladstone, a New Horizons scientist from Southwest Research Institute.

[ NASA ]


Contact the author at george@io9.com and @dvorsky. Top image by NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute; New Horizons spacecraft image: Credits: Photo credit: NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute.

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