NASA's New Horizons Pluto Hours from Liftoff

The first spacecraft ever aimed at the planet Pluto is hours away from launching into space on a nine-year mission to the distant, icy world.

NASA's LIVE webcast of New Horizons' launch begins at 11:00 a.m. EST. Click here.

A Lockheed Martin-built Atlas 5 rocket is poised to launch NASA's Pluto-bound probe New Horizons at 1:24 p.m. EST (1824 GMT) today from Complex 41 at Cape Canaveral Air Force Station in Cape Canaveral, Florida. If successful, today's space shot will begin a more than nine-year trek to Pluto and the Kuiper Belt for the piano-sized spacecraft.

"This is a very exciting time," said Dale Cruikshank, a New Horizons science team collaborator with NASA's Ames Research Center, during Jan. 15 preflight briefing. "We are poised to begin the exploration of a new world, a world we didn't even know that existed until 1930."

Discovered by astronomer Clyde Tombaugh at Flagstaff Arizona's Lowell Observatory in 1930, Pluto is the only planet ever found by a U.S. citizen as well as the only one found in the 20^th Century, NASA officials said.

New Horizons' flyby mission will mark the first time a spacecraft from Earth has visited the small world, which will sit about three billion miles (nearly five billion kilometers) from our planet during the 2015 rendezvous. The spacecraft is also designed to visit one or more icy Kuiper Belt Objects in an extended mission after the flyby.

The spacecraft's launch window extends until about 3:23 p.m. EST (2023 GMT) today, though the probe can launch anytime before Feb. 14 of this year. If the probe launches by Feb. 2, it will be able to snag a speed boost from Jupiter between February and March 2007 and reach Pluto sometime in July 2015, NASA officials said.

New Horizons and its Atlas 5 booster rolled out to the launch pad without a hitch Monday and appear on track for today's planned launch.

Weather officials said Sunday that there is an 80 percent chance of favorable flight conditions above New Horizons' Cape Canaveral launch site, though they will be watching for high winds.

"We are expecting winds in the lower 20 (knots) and mid-20s, and possibly gusts up to 30 knots," said Joel Tumbiolo, the mission's launch weather officer from the 45^th Weather Squadron at the Air Force Station, during a preflight briefing. "All of those are below the threshold for our flight."

NASA will provide live coverage of New Horizons' launch on NASA TV beginning at about 11:00 a.m. EST (1600 GMT). You are invited to follow along using SPACE.com's NASA TV feed by clicking here or the link at the upper left of this page.

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