Pluto, here we come: Unmanned spacecraft lifts off on journey to icy planet

CAPE CANAVERAL, Fla. -- Pluto is considered a planetary oddball -- a tiny, frozen world so unlike the other planets that some astronomers doubt whether it even deserves to be called a planet.

Scientists came a step closer Thursday to understanding Pluto, launching an unmanned spacecraft on a 3-billion-mile journey to the solar system's last unexplored planet.

The New Horizons spacecraft blasted off aboard an Atlas V rocket in a spectacular start to the $700 million mission. Though it is the fastest spacecraft ever launched, capable of reaching 36,000 mph, it will take 9 1/2 years to reach Pluto.

"God has laid out the solar system in a way that requires a certain amount of patience on the part of those who choose to explore it," NASA administrator Michael Griffin said.

The probe, powered by 24 pounds of plutonium, will not land on Pluto but will photograph it, analyze its atmosphere and send data back across the solar system to Earth.

The launch went off without incident to the relief of anti-nuclear activists who had feared an accident could scatter lethal radioactive material.

NASA had postponed the liftoff two days in a row because of wind gusts at the launch pad and a power outage at the spacecraft's control center in Maryland.

"It looked beautiful," said Ralph McNutt Jr. of the Johns Hopkins University of Applied Physics Laboratory, one of the mission's scientists. "I was getting a little bit antsy."