CAPE CANAVERAL AIR FORCE STATION, Fla. -- The launch of NASA's Comet Nucleus Tour, CONTOUR, has been postponed until 2:56 a.m. EDT July 3, Cornell University space scientists said today. The launch previously had been scheduled for the morning of July 1.

Launch organizers said that during installation of the nose cone on the Boeing Delta II rocket on June 27, possible dust contamination was observed on the top solar array panel. As a precautionary measure, the dust is being analyzed to determine its composition and what further action, if any, is necessary.

The spacecraft launch will take place during a 25-day-launch window, which begins July 1. Organizers have said the launch period extends until July 25 without affecting the mission. CONTOUR will orbit the Earth until mid August, when it will fire its thrusters to go into an orbit around the sun, in preparation for its flyby of Comet Encke in November 2003.

Cornell University astronomer Joseph Veverka is leading the international science team on the mission. The mission is managed by the Johns Hopkins University Applied Physics Laboratory.