Pluto images show possible dunes, jumbled mountains

New mysteries and surprises about Pluto abound in the latest images sent back by the New Horizons spacecraft.

Scientists are struggling to interpret and explain the features visible in the newest Pluto photos released by NASA this week, suggesting they may includewind-blown dunes, valleys carved by flowing iceandmountain-like icebergs floating on softer deposits of frozen nitrogen.

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NASA also released a new, sharper image of Pluto's largest moonCharonthat showsa web of fractured plains over large areas of its surface.

Better images of Pluto's moonsCharon, Nix and Hydra will be released Friday.

On July 14,New Horizons became the first spacecraft to make a close flyby of Pluto and its moons. At that time, it sent back a small number of stunning images that have already changed scientists' views of the dwarf planet.

The spacecraft then took a break from sending images to concentrate on providing data from its particle, solar wind and space dust instruments.

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It resumed sending photos on Sept. 5, and will continue to do so for many months. NASA plans to release new images every Friday.

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Among the mysteriesin the latest closeups are large areas with irregular, broken mountains similar to those seen on Jupiter's icy moon Europa.

"The randomly jumbled mountains might be huge blocks of hard water ice floating within a vast, denser, softer deposit of frozen nitrogen within the region informally named Sputnik Planum," suggested Jeff Moore, who leads the New Horizons Geology, Geophysics and Imaging team, in a statement.

Closeups near Pluto's equator show dark craters that appear to represent some of the dwarf planet's most ancient terrain.

Dunes would be 'completely wild'

Nearby are smooth, white plains, along with fine, dark, parallel stripes that look like they could be wind-blown dunes.

"Seeing dunes on Pluto if that is what they are would be completely wild, because Pluto's atmosphere today is so thin," said William B. McKinnon, deputy lead of the New Horizons Geology, Geophysics and Imaging team. "Either Pluto had a thicker atmosphere in the past, or some process we haven't figured out is at work. It's a head-scratcher."

While the atmosphere may be thin, Pluto's atmospheric haze appears to have more layers than scientists expected, NASA says.

The haze also creates a "bonus" twilight that illuminates details of some of the terrain on Pluto's nightside that would otherwise be completely shrouded in darkness, said John Spencer, another deputy lead of the Geology, Geophysics and Imaging team.