NASA's New Horizons probe has snapped some of the best photos yet of Pluto and its large moon Charon. The new photos are now beginning to reveal distinct surface features of the distant dwarf planet, including one bright area that could be a snowy polar cap, mission managers said.
Originally launched in 2006, the New Horizons spacecraft is now just two months away from its historic flyby of the dwarf planet set for July 14.
The craft is still about 70 million miles away from its target, but using an 8-inch telescope aboard the craft it is already able to capture some of the best images yet of Pluto and its moon Charon. Four other moons that have been discovered by the Hubble Telescope are not yet visible to New Horizons.
Pluto rotates on its side much like the planet Neptune and it only takes Charon 6.4 days to complete its trip around the dwarf planet. Currently, Charon doesn't show any major brightness variations, but Pluto is a different story entirely.
"Imagine Pluto on its side, you're looking down essentially on the poles and it's rotating before us like a chicken on a barbecue spit, an almost perpendicular rotation axis to our line of sight," said Alan Stern, the New Horizons principal investigator at the Southwest Research Institute in Boulder, Colo. "Those features are real features on the surface of Pluto, seen for the first time by the New Horizons spacecraft.
"In fact, these images are jut a little bit better than anything that's ever been obtained in history," he said. "They allow us to see that Pluto has very broad surface markings, a wide range of reflectivities on its surface, that there are structures hundreds of miles across that are coherently rotating around the equatorial zone."
At the 3 o'clock position on the planet, "you'll see the image always remains bright," Stern said. "That's a pole, and that may be evidence for a polar cap, which would be very, very exciting. Whether it's actually a polar cap or not depends upon data we'll be collecting in the future, compositional data from our spectrometers, which will begin to come in when we're closer in June."
Mission project scientist, Hal Weaver, said even at Pluto's vast distance from the Sun, very slight variations in temperature can produce polar ice caps.
"The polar cap is a region that's normally a little bit colder than the rest of the surface, and that's where these volatile ices can condense on the surface," he said. "And that's what we think we're seeing. In another month and a half, we're going to actually map the composition, so we'll be able to tell whether or not there's really ice, whether those brightest regions are really ice, snowy patches."
