NASA's New Horizons spacecraft, which has been delighting audiences with the first-ever pictures of Pluto since flying by on Tuesday, snapped a new close-up image showing a "vast, craterless plain that appears to be no more than 100 million years old," NASA said Friday. The frozen region "is possibly still being shaped by geologic processes," according to the space agency.
In a solar system some 4.5 billion years old, that makes Pluto -- which had been reduced to "dwarf planet" status in 2006 -- practically infantile.
"This terrain is not easy to explain," said Jeff Moore, leader of NASA's New Horizons Geology, Geophysics and Imaging Team. "The discovery of vast, craterless, very young plains on Pluto exceeds all pre-flyby expectations."
Because of its home in the Kuiper Belt -- a region of space chock-full of icy objects -- the New Horizons team expected Pluto's surface would have been distressed.
"I would never have believed that the first close up picture we get of Pluto didn't have a single impact crater on it," said Spencer. "That's just astonishing."
Pluto's 'mind blowing' mountains
By all accounts, the decade-long, 3.6 billion-mile journey
has been exceeding expectations and full of surprises
Long thought to be old and pockmarked, Pluto's surface appears to be covered with icy plains, wide smooth areas, and lumpy terrain, judging by the the first images released.
"I'm completely surprised," said Alan Stern, principal investigator for the spacecraft.
Pluto even boasts huge summits dubbed "Norgay Montes" in honor of Tenzing Norgay, one of the first two people to reach the summit of Mount Everest.
"They would stand up respectably against the Rocky Mountains," said John Spencer, a planetary scientist on the New Horizons mission.
"Who would have supposed that there were ice mountains?" said Hal Weaver, another new Horizons project scientist. "It's just blowing my mind."
Pluto's massive ice mountains represents more than just bragging rights for a dwarf planet with perhaps an intergalactic Napolean complex.
It means there is water there -- something scientists have suspected, but never proven, according to Weaver.
"The steep topography means that the bedrock that makes those mountains must be made of H2O -- of water ice," said Stern. "We can be very sure that the water is there in great abundance."
Weaver said expects more data collected by New Horizons will confirm that the ice mountains mean there is plenty of water on Pluto, but it will take about 16 months to download all of the information being gathered by the spacecraft's seven instruments
during the flyby.
NASA also released a new, full globe view of Pluto's largest moon, Charon.
Before the flyby, New Horizons co-investigator Cathy Olkin thought the moon would be an ancient terrain covered in craters.
"Charon just blew our socks off," Olkin said as the new image of the moon was flashed on the screen at a news briefing.
"It's a small world with deep canyons, troughs, cliffs ... dark regions that are still slightly mysterious to us."
She said Charon has a series of troughs and cliffs that extend 600 miles across the surface.
"Pluto did not disappoint. Charon did not disappoint, either," Olkin said.
Besides Charon, Pluto has four other small moons: Styx, Nix, Kerberos and Hydra.
New Horizons captured the first images of Hydra. It's just pixels, but NASA is very excited about it because it shows the elongated moon's size.
Even before New Horizons made its close flyby, a more distant image on Pluto caught the public's imagination: a prominent, bright, heart-shaped region.
That region is being named the "Tombaugh Reggio" in honor of Clyde Tombaugh, the man who discovered Pluto in 1930.
The spacecraft was launched on January 19, 2006, before the big debate started over Pluto's status as a planet. In August of that same year, the International Astronomical Union reclassified Pluto as a dwarf planet.
But Stern has always disagreed with the IAU's decision.
"I don't know what to call this thing except a planet," Stern told CNN.
New Horizons is now more than a million miles on the other side of Pluto. The probe will keep flying out into the Kuiper Belt. NASA may extend its mission and send it to explore another small world.
The New Horizon's mission completes what NASA calls the reconnaissance of the classical solar system
, and it makes the United States the first nation to send a space probe to every planet from Mercury to Pluto.