After completing its historic flyby of Pluto, New Horizons is sending back the first high-resolution images from its encounter. Because of the very low bandwidth that the unmanned probe can sustain across a distance of 4.77 billion km (2.97 billion mi) from Earth, the images are coming in a trickle along with more urgent telemetry, but what has been received so far is already exciting NASA scientists.
One of these new images is a close up of the equatorial region of Pluto near the heart-shaped plain. It was captured an hour and a half before the flyby at a distance of 47,800 mi (77,000 km) and has enough resolution to distinguish features less than a mile in diameter.
These features include a mountain range rising up to 11,000 ft (3,500 m) above the surface of Pluto, but New Horizon scientists say they aren't composed of granite or basalt as on Earth, but of the water ice that makes up the bedrock of the frozen planet. NASA says that though much of the surface of Pluto is made of nitrogen and methane ice, these aren't strong enough to support the weight of mountains, but water ice acts like rock at hundreds of degrees below freezing. So instead of Pluto's peaks being ice covered, they're just ice.
What NASA finds so exciting isn't that the mountains exist, but that they're very young. The space agency says that the lack of meteor craters in the region indicates that they're only about 100 million years old, which makes them the youngest features in the Solar System. This means that Pluto could be geologically active, and since it doesn't orbit a gas giant that could heat its interior with tidal forces, some other mechanism may be at work.
Another discovery sent back by New Horizons was spectrographic maps of Pluto, which measure the amount of methane ice on its surface. Scientists expected to find it there in great quantities, but Pluto had another surprise in that the methane isn't evenly distributed and has different textures. NASA compares this phenomenon to snow on Earth, which appears fluffy when newly fallen, but turns bluish as it compacts..
“We just learned that in the north polar cap, methane ice is diluted in a thick, transparent slab of nitrogen ice resulting in strong absorption of infrared light,” says New Horizons co-investigator Will Grundy, Lowell Observatory, Flagstaff, Arizona.
In addition to the planet, New Horizons also made detailed examinations of Pluto's largest moon, Charon and the four smaller ones: Nix, Hydra, Styx and Kerberos. Another high-resolution shot released today shows Charon as seen from the spacecraft's Long Range Reconnaissance Imager (LORRI) on July 13 at a distance of 289,00 mi (466,000 km).
Based on another unexpected lack of meteor impacts, the surface of Charon is very young, which indicates recent geological activity, and shows cliffs 600 mi (1,000 km) long that appear to be due to the crust fracturing, and a canyon 4 to 6 mi (7 to 9 km) deep. In addition, there is a dark staining in the north polar region that seems to be a thin deposit of some yet to be determined material.
The final image released was a preview of one of the smaller moons, Hydra. The image was captured by LORRI at a distance of 400,000 mi (644,000 km) and is a bit low-res, but it shows an irregular body about 27 x 20 mi (43 x 33 km) that seems to be coated with water ice.
"The mission has had nine years to build expectations about what we would see during closest approach to Pluto and Charon," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate in Washington. "Today, we get the first sampling of the scientific treasure collected during those critical moments, and I can tell you it dramatically surpasses those high expectations."
More wonders will no doubt be revealed as New Horizons continues to send back its data.
In the meantime, check out just how New Horizons reached its destination in our latest State of the Game video.
Source: NASA
