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	Immediate Search Planned for More Moons of Pluto By Robert Roy Britt Senior Science Writer posted: 04:14 pm ET 24 February 2003

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Pluto might have more than one satellite, researchers speculated today, and they aim to find out before the end of the year.

Pluto has one known moon, Charon. But Pluto is not like most planets, being small, far out and highly inclined to the plane in which the other planets orbit. Astronomers generally view it as one of many so-called Kuiper Belt Objects that roam the outer solar system, often in pairs and possibly larger packs.

There are seven known pairs of rocks out near and beyond Pluto. (Many asteroids, which typically orbit the Sun between Mars and Jupiter, also have travelling companions.)

Might Pluto harbor more satellites that haven't been found simply because no one has looked close enough? A survey should tell, the astronomers said.

"It's something we plan to complete relatively quickly -- that is, this year," said Harold Weaver of the Johns Hopkins University Applied Physics Laboratory. "We will use both ground-based telescopes and, we hope, the Hubble Space Telescope."

Weaver is part of the Hopkins New Horizons science team, which hopes to send a probe to Pluto starting in 2006. It would arrive in about 2015 and study the tiny planet and then continue on in search of Kuiper Belt Objects. Finding more moons around the Pluto would give further impetus to such a robotic mission, which awaits final NASA approval.

"Discovering another moon or moons around Pluto-Charon would be exciting in and of itself, and could tell us a lot about the dynamical evolution of this unique, binary system," said New Horizons Principal Investigator Alan Stern, of the Southwest Research in Boulder, Colo.

"Whether or not we find new moons of Pluto, we expect to learn more about how and where Kuiper Belt satellites form. And, of course, any discoveries of new moons of Pluto would become targets of interest for the New Horizons flyby of the Pluto-Charon system."

The first Kuiper Belt Objects were discovered only in 1992. Astronomers think they are similar to planetary building blocks and are leftovers from the solar system's early years.

Charon is the largest satellite in our solar system relative to its planet. At 745 miles wide (1,200 kilometers) it is more than half the diameter of Pluto. Stern said just a few days of telescope time should reveal other satellites, if any exist, down to 6 miles (10 kilometers).