pbr The Delta IV Heavy Launch Vehicle rocket has taken off from Vandenberg Air Force Base in California.br ppbr It is the largest rocket ever to launch from the US west coast.br ppbr The Space Launch Complex-6, or SLC-6, has undergone three years of "preparations and $100 million in base infrastructure upgrades" to accommodate "payloads of all sizes to orbit" for rockets including the Delta IV.br ppbr On this mission, Delta IV carried a national security payload for the National Reconnaissance Office.br ppbr The launch marks the fifth launch of the Delta IV in the program's history, with the first launch taking place in January of 2004 on the east coast.