Delta IV Heavy NROL 15

The sixth flight of the Delta IV Heavy occurred at 9:16 AM EDT on June 29, 2012. The payload was a reconnaissance satellite for the National Reconnaissance Office.    This flight marked the first time the upgraded RS-68A flew on a vehicle. The RS-68A produces more thrust than the previous version of the engine, making this the most powerful Delta IV ever flown at 2.1 million pounds of thrust from three main engines on the Common Booster Cores.