LONDON: Images from NASA’s New Horizons spacecraft suggest that Pluto has a polar cap made of some kind of ice.
The pictures, taken over the past few weeks and released on April 29, show Pluto with its largest moon, Charon. The dwarf planet’s surface is mottled with light and dark patches, each measuring hundreds of kilometres across. But its pole remains bright no matter how Pluto rotates, suggesting that a highly reflective icy cap may exist there. “It’s very suspiciously suggestive,” says Alan Stern, the mission’s principal investigator, who is based at the Southwest Research Institute in Boulder, Colorado.
“It’s rare to see any planet in the Solar System at this low resolution displaying such strong surface markings,” he adds. “It’s a mystery whether these bright and dark regions are caused by geology or topography or composition.”
Light and dark patches have previously been spotted on Pluto by the Hubble Space Telescope. New Horizons, which is currently about 90 million kilometres from Pluto, is now taking higher-resolution images than Hubble did, but it is not as sensitive to faint objects. Image-processing techniques have allowed mission scientists to tease out surface details about a month earlier than expected, says project scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.
