Jan. 19 (Bloomberg) -- NASA's mission to Pluto lifted off from the Kennedy Space Center in coastal Florida today on a planned nine-and-a-half-year mission to visit the farthest known planet in the solar system.

The grand piano-sized New Horizons spacecraft was carried aloft on a Lockheed Martin Corp. Atlas V rocket at about 2 p.m. local time at Kennedy Space Center. The launch under partly cloudy skies was broadcast live on television.

New Horizons, the first probe to visit the planet, will use Jupiter's gravitational pull to propel it toward Pluto in a 4.7 billion-mile (7.6 billion-kilometer) trek. The National Aeronautics and Space Administration will shave about three years from the trip by using the Jupiter route.

The craft is scheduled to arrive at Pluto in July 2015 for a five-month study of the planet and its moon Charon. It will be the first mission to the Kuiper Belt, a region of rocky, icy objects orbiting the sun beyond Neptune that scientists believe may contain some of the original elements that led to the formation of life.

``It's going to end up actually telling us something about Pluto specifically but about these bodies out in the solar system in general,'' said Ralph McNutt, principal investigator for the mission's instrument that will examine the interaction between the planet's atmosphere and the solar wind, a stream of energized particles streaming out from the sun.

Extended Mission

The launch was postponed due to ground winds exceeding safety limits on Jan. 17 and again yesterday because of a power disruption at Johns Hopkins University's Applied Physics Laboratory in Laurel, Maryland, which designed the spacecraft and is managing the mission for NASA.

After its visit to Pluto, pending approval of an extended mission, New Horizons may travel deeper into the Kuiper Belt to search for objects as large as 60 miles across that might have an atmosphere and moons.

A longer mission might even head for remote objects almost the size of Pluto, such as red-hued Sedna, according to agency spokesman Dean Acosta. Sedna was found in November 2003, lying in the Kuiper Belt about three times farther from the sun than Pluto.

Seven Instruments

New Horizon's seven scientific instruments will examine Pluto's surface, its geology, its composition and atmosphere. The Hubble Space Telescope can't even see details of its icy, rocky surface. The probe will come within 6,200 miles of Pluto and should be able to take images of features as small as 200 meters across.

``It really is a window on the past,'' McNutt said in a telephone interview from Florida. ``We know you can always sit back in a chair and think about these things, but to really know what's going on you have to take a look.''

Scientists will check on the progress of their craft each year and run computer simulations to ensure the project is on course. Alan Stern, the principal investigator, and his team ``have devoted major portions of their careers to it and have a good-sized chunk yet to go before they see results,'' NASA Administrator Michael Griffin said on Jan. 17.

Astronomers debate whether Pluto is actually a planet and how big a sun-orbiting object has to be before it is considered a world. Its status was called into question earlier this year with the discovery of a possible 10th planet.

The 1,054-pound, 7-foot-tall spacecraft will first fly to Jupiter in February 2007, coming four times closer to the solar system's largest planet than the Cassini probe that passed by on its way to Saturn in 2004.

To contact the reporter on this story: Chris Dolmetsch in New York at cdolmetsch@bloomberg.net.

Last Updated: January 19, 2006 15:29 EST