The New Horizons spacecraft closing in on Pluto has returned new, stunning images of the icy dwarf planet. The images reveal, for the first time, the presence of polar caps on the body, much like those seen on Earth.
New Horizons took the latest set of photographs between May 8-12, as the vehicle continued to close in on the distant body. During the month following the middle of April, New Horizons traveled around 20 million miles.
The Long-Range Reconnaissance Imager (LORRI) was used to record the images while the spacecraft closed from 68 to 47 million miles. Each day, the spacecraft draws another 750,000 miles closer to the dwarf planet. Close approach with Pluto is scheduled for July 14, 2015. The system is believed to contain five moons, although more may be discovered during the mission.
Pluto rotates around its own axis once every 6.4 Earth days, and images taken over time can be processed to bring out detail on the surface. However, this process can sometimes result in details being shown where none exist, so fine details in the photos will need to be confirmed as the spacecraft draws closer to the system. When New Horizons makes its close approach with Pluto, it will be able to examine the world with a spectroscope to determine the chemical composition of the surface.
"These new images show us that Pluto's differing faces are each distinct; likely hinting at what may be very complex surface geology or variations in surface composition from place to place. These images also continue to support the hypothesis that Pluto has a polar cap whose extent varies with longitude," said Alan Stern from the Southwest Research Institute.
New Horizons was launched to Pluto in January 2006, when that distant world was still classified as the ninth planet. Just months after launch, Pluto was reclassified as a dwarf planet. This decision by astronomers met with widespread public disapproval by many people who grew up knowing Pluto as a full-fledged planet.
The spacecraft is currently 2.95 billion miles from the Earth, and all systems on board the vehicle appear to be in operational condition. After the observatory flies past Pluto, it is possible New Horizons could visit more distant, smaller bodies in the Kuiper belt, far beyond the reach of the planets.
At its closest approach, mission planners believe they will be able to image Pluto with a resolution 5,000 times greater than these latest photographs.
