NASA Probe Nearing Close Encounter With Unexplored Pluto

The first spacecraft to visit distant Pluto, a dwarf planet in the solar system's frozen backyard, is still three months away from a close encounter, but already in viewing range, newly released photos show.

The New Horizons probe blasted off from Florida in January 2006 for a 3-billion-mile (5-billion-km) journey to the Kuiper Belt region of the solar system located beyond Neptune.

During that time, Pluto once known as the ninth planet in the solar system, was demoted to dwarf planet status after the discovery of similar icy bodies in eccentric, distant orbits around the sun.

New Horizons will pass will pass about 7,750 miles(12,500 km) from Pluto's surface on July 14.

With a diameter of just 1,430 miles (2,302 km) - roughly two-thirds the size of Earth's moon - Pluto still looks like a bright dot in color images released by NASA on Tuesday.

For now, the pictures have more value to engineers than scientists. They are serving as a road map for control teams to tweak New Horizon's approach.

The spacecraft does not have the fuel for a braking burn to put itself into orbit around Pluto. Rather, like the Voyager explorations in the late 1970s and 1980s, New Horizons will make its observations on the fly.

"Our team has worked hard to get to this point, and we know we have just one shot to make this work," Alice Bowman, New Horizons mission operations manager at the Johns Hopkins University Applied Physics Laboratory, said in a statement.

"We've plotted out each step of the Pluto encounter, practiced it over and over, and we're excited the 'real deal' is finally here."

After close-up studies of Pluto, its primary moon, Charon, and entourage of at least four smaller moons, New Horizons will continue speeding out into the Kuiper Belt, a region peppered with what are believed to be frozen remnants from the formation of the solar system some 4.6 billion years ago.

The team plans to petition NASA for additional funds for a flyby of a second Kuiper Belt object in 2019.

In addition to its cameras, the spacecraft is outfitted with six scientific instruments, including light-splitting spectrometers, and plasma and dust detectors, to study the geology of Pluto and Charon, map their surface compositions and temperatures and look for an atmosphere, ring system and other moons.