A 24-story Delta 4-Heavy rocket, the world's largest, lifts off at 9:15am EDT June 29 with the NROL-15 payload
for the National Reconnaissance Office. The launch marked the first flight of the RS-68A main engines, an upgrade
of the Delta 4 rocket's core engines that provides more thrust (over 702,000 lbs at liftoff compared to about
656,000) and which thus can boost more payload into orbit. It also marked the first daytime launch of a Heavy
at Cape Canaveral since the debut mission in December 2004.
