Official Nasa Communication Release-20070705

07.05.07 George Diller Kennedy Space Center, Fla. 321-867-2468 MEDIA ADVISORY: 35-07 NASA POSTPONES LAUNCH OF DAWN SPACECRAFT CAPE CANAVERAL - The launch of NASA's Dawn spacecraft aboard a United Launch Alliance Delta II rocket has been postponed 24 hours. A lightning advisory Thursday morning precluded the start of the Delta II second stage fueling as scheduled and did not clear in time for an afternoon attempt. Fueling has been rescheduled for Friday, July 6. Fueling on Thursday was also delayed because the temperature of the second stage was too warm for the process to begin. The fairing temperature has been lowered so that oxidizer can be loaded Friday pending acceptable weather. Dawn's launch countdown dress rehearsal has been postponed until Friday. The launch window on Sunday, July 8, extends from 4:04 to 4:33 p.m. EDT. The chance of not meeting the launch weather criteria on Sunday is 60 percent. Required launch telemetry assets downrange will be in place to support the launch. The Dawn mission science briefing, scheduled for Friday, will be held as planned at 1 p.m. The prelaunch news conference will begin at 1 p.m. Saturday, following the launch readiness review. For more information about Dawn, visit: http://www.nasa.gov/dawn -end-