A ULA Delta IV lifted off from Cape Canaveral Air Force Station’s Space Launch Complex-37 Thursday evening at 8:59 p.m. Carried to orbit at 11,000 nautical miles and an inclination of 55 degrees was a 3,534 lb. Global Positioning System 2F satellite. The Boeing built spacecraft will take its place in the 31 satellite fleet, which will also include 6 older, semi-retired “birds” as on-orbit spares.
Yesterday’s launch, the 25th of a Boeing Delta IV came after months of delay rising from uncertainty in determining the root cause of an underperforming upperstage RL-10B-2 engine in a similar launch in October 2012. Although ULA has maintained a sterling launch success record, that particular flight was a very close call, and had it not happened to be carrying a relatively lightweight GPS satellite would have likely resulted in either a failure, or a spacecraft deposited in lower than intended orbit, requiring use of on-board propellants for correction.
Although the Delta IV conducted its maiden flight carrying a commercial payload, Eutalsat W5 on 11/20/2002, it was pulled from the market the next year, and has not returned.
For an update on the current status of the EELV program, please see EELV’s Era of Transition in The Space Review