CENTENNIAL, Colo., April 29, 2016 (ULA PR) — ULA successfully delivered the OA-6 Cygnus spacecraft to its precise orbit as planned on March 22. During the launch, the system experienced a premature first stage shutdown. Atlas is a robust system. The Centaur upper stage compensated for the first stage anomaly, delivering Cygnus to a precise orbit, well within the required accuracy. The ULA engineering team has reviewed the data and has determined an anomaly with the RD-180 Mixture Ratio Control Valve (MRCV) assembly caused a reduction in fuel flow during the boost phase of the flight. In addition to analysis and testing, all RD-180 engines are being inspected.
Last Friday, in preparation for the MUOS-5 launch, the Atlas V completed the Launch Vehicle on Stand (LVOS) operation, erecting the Atlas V into the Vertical Integration Facility at Cape Canaveral Air Force Station. LVOS will allow configuration of the vehicle to support RD-180 engine inspections and confirm all engine components are ready for launch. The Atlas V MUOS-5 launch is targeted for early summer; a new launch date has not been secured on the Eastern Range. The impact to the remainder of the Atlas V manifest is in review with new launch dates being coordinated with our customers. All missions manifested for 2016 are expected to be successfully executed by the end of the year, including OSIRIS-REx, which will remain in early September to support its critical science window.