Pluto's Weirdly Young Surface Doesn't Make Sense
Scientists with NASA’s New Horizons mission are puzzling over how a world that never gets more sun than Earth at twilight is reshaping its surface, filling in craters, cracking its crust and building towering mountains and smooth hills.
Scientists with NASA's New Horizons mission are puzzling over how a world that never gets more sun than Earth at twilight is reshaping its surface, filling in craters, cracking its crust and building towering mountains and smooth hills.
With just 1 percent of the 50 gigabytes of data collected during New Horizons' approach and close encounter with Pluto back on the ground, scientists already are rethinking long-held ideas about icy bodies in the outer reaches of the solar system.
Pluto, for example, appears far from a pristine remnant left over from the formation of the solar system some 4.6 billion years ago. Its surface is brimming with evidence of relatively current, and possibly ongoing, geological processes.
New Horizons was dispatched to study Pluto and other icy bodies in the Kuiper Belt, located beyond Neptune's orbit.
Pluto, and to some extent its big moon Charon, have young and varied terrains, New Horizons found.
"The landscape is just astoundingly amazing," New Horizons scientist Jeffrey Moore, with NASA's Ames Research Center in Moffett Field, Calif., told reporters on a conference call.
A second batch of pictures released on Friday shows that part of Pluto's bright, heart-shaped region (since named "Tombaugh Regio" for Pluto's discoverer Clyde Tombaugh) contains a vast, crater-free plain, estimated to be less than 100 million years old.
Resembling frozen mud cracks on Earth, the region, nicknamed "Sputnik Planum" is broken into irregular shaped polygons, roughly 12- to 20 miles in diameter, that are boarded by what appear to be shallow troughs.
"Those could be only a week old, for all we know," Moore said.
The polygons could have been formed by convection, patterns etched in Pluto's surface ice like the roiling surface of a pot of boiling oatmeal. What drives the process, however, has yet to be determined.
The polygons also could be like mud cracks, created by contraction of the surface, Moore added.
New Horizons pictures also show that some of the troughs have dark material in them. Others are encircled by hills that seem to rise above the surface.
"We suspect the hills may have been pushed up from underneath along the cracks," Moore said.
Another theory is that the hills are mounds of more resistant material after the surrounding plains have eroded away.
"We don't know which of those two explanations are correct," he added.
In the center left of Pluto’s vast heart-shaped feature -- informally named “Tombaugh Regio” -- lies a vast, craterless plain that appears to be no more than 100 million years old, and is possibly still being shaped by geologic processes.
After several false starts, NASA in 2001 agreed to fund an independent effort to fly a spacecraft to Pluto, the only member of the solar system’s original nine planets that hadn’t been explored. Five years later, New Horizons blasted off to begin a nearly 3 billion mile journey to Pluto, farther than any probe has traveled since the 1970s-era Pioneer and Voyager spacecraft.
Here’s a look at the New Horizons mission by the numbers.
Launching a small spacecraft on a big rocket is one way to get going fast. Slingshotting off giant Jupiter’s gravity is another. New Horizons did both, and still the journey to distant Pluto took nearly 10 years. It is zipping along at about 31,000 mph -- fast enough to fly from New York City to Los Angeles in less than 5 minutes.
Image: Viewed from the top of the Vehicle Assembly Building at Kennedy Space Center, NASA’s New Horizons spacecraft roars off the launch pad aboard an Atlas V rocket on Jan. 19, 2006.
At its closest approach, New Horizons will pass about 7,750 miles from Pluto and about 17,900 miles from its orbital mate Charon. The view will be about 500 times better than this image, taken on July 7 when New Horizons was just less than 5 million miles from Pluto. New Horizons will pass through the Pluto system in about 30 minutes. The probe carries seven science instruments, including LORRI, the Long Range Reconnaissance Imager, telescope.
During the encounter, New Horizons will take hundreds of pictures in both visible and near-infrared wavelengths. The best images should depict surface features as small as 200 feet across. With nearly 3 billion miles between New Horizons and Earth, a radio signal, which travels at the speed of light, will take about 4.5 hours to reach Earth.
Image: An artist's impression of Pluto's surface reveals an icy surface -- we're about to find out what Pluto is really made of.
With just one shot to get a close-up view of Pluto, New Horizons is designed to gather as much data as possible, as quickly as possible. In all, scientists expect the spacecraft to collect 100 times more data during closest approach than it can transmit back to Earth just after the encounter. A few high-priority images and data will be sent back just before and after closest approach, but the rest will trickle in over the next 16 months.
Image: Diagram showing the sequence of events during New Horizons' encounter with the Pluto system.
New Horizons draws electricity from a single radioisotope thermoelectric generator, or RTG, which converts heat given off by the natural decay of about 24 pounds of radioactive plutonium. It runs on less power than a pair of 110-watt light bulbs.
Image: Artist's impression of New Horizons flying past Jupiter, with its RTG visible in the lower right of the image.
After its Pluto flyby, New Horizons will continue out into the Kuiper Belt region of the solar system. Scientists hope to extend its mission so it can pass by at least one of the thousands of icy bodies that orbit in this vast domain. Eventually, New Horizons will end up leaving the solar system. It is expected to remain viable until the late 2030s.
Image: Artist's impression of New Horizons encountering a Kuiper Belt object beyond Pluto.