Asteroid Masursky pictured by the Saturn-bound Cassini probe. Photo: NASA/JPL

New images taken by the camera onboard the Saturn-bound Cassini spacecraft are giving scientists the first size estimates on asteroid 2685 Masursky and preliminary evidence that it may have different material properties than previously believed.

"The Masursky images represent the first time that Cassini has gathered information on a body not extensively studied from Earth," said Carolyn C. Porco, Cassini imaging team leader and associate professor at the Lunar and Planetary Laboratory of the University of Arizona, Tucson.

The images, taken on Jan. 23, also marked the first use of Cassini's automated object-targeting capabilities, and they functioned as expected, Porco said.

Launched October 15, 1997, Cassini flew by Venus and Earth before heading toward a flyby of Jupiter next December. It entered the asteroid belt between Mars and Jupiter, a region populated by asteroids, in mid-November of 1999.

Cassini's camera took pictures of the asteroid when the spacecraft was 7 hours and 5-1/2 hours before closest approach, at a distance of 1.6 million kilometers (960,000 miles). Since Masursky is too small to be measured from Earth, scientists hoped Cassini could help them determine its size, as well as its reflectivity, asteroid category, and possibly its rotation period.

"So far, the images reveal that the side of Masursky imaged by Cassini is roughly 15 to 20 kilometers (9 to 12 miles) across," Porco said.

The Cassini spacecraft is scheduled to arrive at Saturn in July 2004 to begin a four-year exploration of the ringed planet and its moons. The Cassini mission is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif., for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.