A United Launch Alliance (ULA) operated Atlas V rocket in the 541/RL10C-1 configuration successfully lifted off at 0549 GMT on 24 September 2017 from the Vandenberg launch site in California. It was carrying the NRO L-42 spacecraft for the US National Reconnaissance Office (NRO). The spacecraft concerned is believed to be a Trumpet Follow-on 2 class ELINT (Electronic Intelligence) spacecraft with a SBIRS HEO-4 early warning payload aboard. As such, the spacecraft was believed to be heading for an elliptical “Molniya” class orbit of approximately 38200 x 2100 km at 62.8 degrees inclination relative to the equator, and whose long 717 minute period means that the spacecraft that “hangs” for a long period over the northern latitudes.
