Artist Rendering of the Genesis Spacecraft

The launch of NASA's Genesis spacecraft aboard a Delta II rocket was postponed today because of thick cloud conditions in the flight path of the launch vehicle. Launch will now occur no earlier than 12:27:09 p.m. EDT (9:27:09 a.m. PDT) on Thursday, Aug. 2.

Mission managers will assemble for a weather update at about 10 p.m. EDT tonight to determine the feasibility of a launch attempt Thursday. The current forecast indicates an 80 percent chance of weather violation Thursday, a 60 percent chance of violation Friday and a 40 percent chance of violation Saturday. The primary concerns are rain showers, thick clouds and thunderstorms.

No significant technical issues were worked during the countdown, and the Delta II rocket and Genesis spacecraft remain in excellent health. The two-minute launch window opens Friday at 12:23:53 p.m. EDT (9:23:53 a.m. PDT), and Saturday at 12:23:40 p.m. EDT (9:23:40 a.m. PDT).

The thick cloud rule prohibits launch if the vehicle's flight path travels through nontransparent clouds greater than 4,500 feet (about 1,370 meters) thick. Updates from the weather reconnaissance aircraft reported clouds 8,000 feet (about 2,440 meters) thick in the Delta's flight path during the final built-in hold at T-4 minutes.