December 16, 2005

NASA’s First Pluto Probe Heads to Launch Pad

By Irene Klotz

CAPE CANAVERAL, Florida (Reuters) - A small spacecraft bound for Pluto was being prepared for transfer to the launch pad on Friday in preparation for blastoff next month, NASA officials said.

New Horizons is the centerpiece of a $650 million mission to explore the last of the solar system's original nine planets. Scientists recently have discovered hundreds of Pluto-like objects orbiting more than 50 times farther away from the sun than Earth.

NASA is giving New Horizons one of the biggest boosts into space money can buy.

The small probe, which weighs about 1,000 pounds (454 kg) and is about the size of a grand piano, will be carried into orbit by a Lockheed Martin heavy-lift Atlas launch vehicle outfitted with five solid-rocket boosters, a Centaur liquid-fuel upper stage and a STAR 48B solid-fuel third stage -- equipment more commonly used for hefty communications satellites than relatively petite science probes.

"It's almost going to look like a hood ornament on top of that big rocket," Kennedy Space Center spokesman George Diller said. "We want to give it a lot of speed to get to Pluto as fast as we can."

If the Apollo capsules had as much power behind them, the trip to the moon would have taken about nine hours instead of three days, Diller added.

New Horizons' mission is to study Pluto, its primary moon Charon and two other newly discovered satellites, then continue on into the Kuiper Belt region beyond Pluto to fly past other icy objects.

The Kuiper Belt is a ring of space objects that may be remnants from the early solar system.

"All the planets were formed in the same epoch," said Alan Stern, the mission's principal investigator. "Out in the Kuiper Belt, objects started to grow, but then something happened. They ran out of feedstock."

The probe contains 24 pounds (10.9 kg) of plutonium pellets, which will provide power through radioactive decay. Due to Pluto's distance from the sun, solar power is not a viable option.

Scientists will have to wait at least 9-1/2 years to begin studying the scientific data the probe beams back, and even longer if New Horizons misses the opening of its launch period on January 11.

If the probe is not launched by February 2, New Horizons will miss the opportunity to pick up extra speed by zooming close to Jupiter in 2007 for a slingshot boost from the giant planet's gravity. A direct flight to Pluto would take an additional three years, scientists estimate.

At its speed, there is no chance New Horizons can slow down and enter into orbit around Pluto for an extended stay. The probe does not carry the tremendous amount of fuel required for a braking maneuver.

Instead, the spacecraft and its sensors will target Pluto and its moons from about five months before closest approach to one month after, then head out in search of new subjects.