NASA Pluto probe awakens at edge of solar system after nine-year journey

After nine years and a journey of 3 billion miles, NASA's New Horizons robotic probe awoke from hibernation to begin an unprecedented mission to study the icy dwarf planet Pluto and other mini-planets in its Kuiper Belt home.

A pre-set alarm clock roused New Horizons from its electronic slumber on Saturday at 3 p.m. EST, though ground control teams didn’t receive confirmation until just after 9:30 p.m. New Horizons is now so far away that radio signals traveling at the speed of light take four hours and 25 minutes to reach Earth.

The scientific observation of Pluto, its entourage of moons and other bodies in the solar system's frozen backyard begins Jan. 15, program managers said. The probe’s closest approach to the planet is expected on July 14.

The craft's onboard instruments include advanced imaging infrared and ultraviolet spectrometers, a compact multicolor camera, a high-resolution telescopic camera, two powerful particle spectrometers and a space-dust detector, according to a press release from NASA.

By mid-May, New Horizons should be able to transmit better views of Pluto and its moons than the Hubble Space Telescope, NASA said.

“New Horizons is on a journey to a new class of planets we’ve never seen, in a place we’ve never been before,” New Horizons Project Scientist Hal Weaver said in the release. “For decades we thought Pluto was this odd little body on the planetary outskirts; now we know it’s really a gateway to an entire region of new worlds in the Kuiper Belt, and New Horizons is going to provide the first close-up look at them.”

Pluto lies in the Kuiper Belt, a region of icy mini-planets orbiting the sun beyond Neptune that are believed to be leftover remains from the formation of the solar system some 4.6 billion years ago. It is the last unexplored region of the solar system.

"It's hard to underestimate the evolution that's taking place in our view of the architecture and content of our solar system as a result of the discovery ... of the Kuiper Belt," lead researcher Alan Stern said.

Since its discovery in 1930, Pluto has been a mystery. Scientists struggled to explain why a planet with a radius of just 740 miles – about half the width of the United States - could come to exist beyond the giant worlds of Jupiter, Saturn, Uranus and Neptune.

"We wondered why Pluto was a misfit," Stern said.

In 1992, astronomers discovered that Pluto, located about 40 times farther away from the sun than the Earth is, was not alone in the far reaches of the solar system, prompting the International Astronomical Union to reconsider its definition of "planet."

In 2006, with New Horizons already on its way, Pluto was stripped of its title as the ninth planet in the solar system and became a dwarf planet, of which more than 1,000 have since been discovered in the Kuiper Belt. With New Horizons approaching Pluto's doorstep, scientists are eager for their first close-up look at this unexplored domain.

Al Jazeera and Reuters