Pluto’s ‘heart’ packs craterless plain featuring irregularly-shaped segments


New Horizons is now busy sending back the data it collected during its July 14 flyby of Pluto and details NASA is receiving from the spacecraft is providing information about the dwarf planet that wasn’t known before.

In the latest set of images sent across by New Horizons spacecraft is a close-up view of Pluto’s heart featuring craterless plain, which scientists at NASA say isn’t likely to be more than 100 million years old.

This frozen region, featuring irregularly-shaped segments resembling frozen mud cracks on Earth, is still possibly being shaped by geological processes. This frozen region is north of Pluto’s icy mountains, in the center-left of the heart feature, informally named “Tombaugh Regio” (Tombaugh Region) after Clyde Tombaugh, who discovered Pluto in 1930.

Scientists haven’t been expecting this sort of terrain on Pluto and Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging Team (GGI) at NASA’s Ames Research Center in Moffett Field, California says that this particular terrain isn’t easy to explain.

This region has been informally named “Sputnik Planum” (Sputnik Plain) after the Earth’s first artificial satellite. Featuring a broken surface of irregularly-shaped segments, this region is roughly 12 miles (20 kilometers) across and is bordered by what appear to be shallow troughs.

The toughs are also interesting for the fact that they have darker material within them at some places while areas have clumps of hills that appear to rise above the surrounding terrain.

Elsewhere, the surface appears to be etched by fields of small pits that may have formed by a process called sublimation, in which ice turns directly from solid to gas, just as dry ice does on Earth.

How were these segments formed?

Geologists have been working on two theories to explain how these segments may have formed. Scientists say that this irregularly shaped terrain could be a result of the contraction of surface materials, similar to what happens when mud dries. An alternate theory is that these segments may be a product of convection, similar to wax rising in a lava lamp.

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On Pluto, convection would occur within a surface layer of frozen carbon monoxide, methane and nitrogen, driven by the scant warmth of Pluto’s interior.

There are also few miles long dark streaks across the icy plains, which appear to be aligned in the same direction and may have been produced by winds blowing across the frozen surface.

The Tuesday “heart of the heart” image was taken when New Horizons was 48,000 miles (77,000 kilometers) from Pluto, and shows features as small as one-half mile (1 kilometer) across. Mission scientists will learn more about these mysterious terrains from higher-resolution and stereo images that New Horizons will pull from its digital recorders and send back to Earth during the next year.

Pluto’s Atmosphere

Based on the data received, New Horizons Atmospheres team says that Pluto’s atmosphere extends as far as 1,000 miles (1,600 kilometers) above the surface, demonstrating that Pluto’s nitrogen-rich atmosphere is quite extended. This is the first observation of Pluto’s atmosphere at altitudes higher than 170 miles above the surface (270 kilometers).

There is also a region of cold, dense ionized gas tens of thousands of miles beyond Pluto — the planet’s atmosphere being stripped away by the solar wind and lost to space.

“This is just a first tantalizing look at Pluto’s plasma environment,” said New Horizons co-investigator Fran Bagenal, University of Colorado, Boulder.

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

Alan Stern, New Horizons principal investigator from the Southwest Research Institute (SwRI), Boulder, Colorado, added, “We’ve only scratched the surface of our Pluto exploration, but it already seems clear to me that in the initial reconnaissance of the solar system, the best was saved for last.”