Jan. 15 (Bloomberg) -- A NASA capsule carrying pieces of a comet landed safely at a U.S. Air Force testing range in the Utah desert this morning after a two-year journey aboard the agency's Stardust spacecraft.

Stardust was launched Feb. 9, 1999, and traveled about 2.12 billion miles to the comet Wild 2, arriving on Jan. 2, 2004. It came within 149 miles of the comet that day, collecting a sample of the particles that surround its nucleus in a 32-inch-wide, 101-pound container.

The Lockheed Martin Corp.-built spacecraft then traveled 752 million miles back to Earth, dropping the capsule at about 1:57 a.m. New York time this morning, NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement. The capsule landed at the Air Force's Utah Test and Training Range near Dugway at about 5:10 a.m.

Comets are celestial bodies formed in the cold expanses of space beyond the planets, made up of ice and embedded dust. Stardust program scientists hope examining the contents of the sample return capsule will show the exact composition of Wild 2 and help them understand how the solar system formed.

``The Stardust project has delivered to the international science community material that has been unaltered since the formation of our solar system,'' Tom Duxbury, the Stardust project manager, said in a statement.

The capsule will now be shipped to Johnson Space Center in Houston, where it will be opened, inspected and analyzed. The $168 million mission is a partnership of the National Aeronautics and Space Administration, the University of Washington and the Jet Propulsion Laboratory.

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

Last Updated: January 15, 2006 15:44 EST