ULA: Anomaly on OA-6 mission originated in first stage fuel system

Jason Rhian

CAPE CANAVERAL, Fla. — United Launch Alliance (ULA) is investigating the cause of the premature first stage shutdown that occurred during the March 22, 2016, launch of Orbital ATK’s S.S. Rick Husband (Cygnus) spacecraft. According to a statement issued by the Colorado-based firm, the issue was tracked down to the Atlas V 401 first stage’s fuel system.

Despite the anomaly, Cygnus was successfully delivered to the proper orbit thanks to the booster’s Centaur upper stage (powered by a lone Aerojet Rocketdyne RL10C-1 engine) burning about a minute longer than the 14 minutes that were anticipated.

The freighter, and its roughly 7,745 lbs (3,513 kg) of cargo, experiments, and crew supplies, arrived at the International Space Station on Saturday, March 26. The supply run was carried out as part of the $1.9 billion Commercial Resupply Services contract that Orbital ATK has signed with NASA.

During ascent, the Russian-built RD-180 rocket engine cut off approximately 6 seconds earlier than was planned. A final word on the anomaly has not been issued, ULA has stated that it is working with its industry partners to determine the exact cause of the incident.

Standard operating procedure whenever something like the March 22 incident takes places is the formation of a review team to study the incident in detail with key participants being involved in the process. To date, the Atlas V has performed almost flawlessly with only a single, partial failure of the NROL-30/USA-194 marring that track record (although the payload was able to reach its intended orbit, under its own power, which will limit the classified payload’s operational life – according to a report appearing on SpaceFlight Now).

Because of this recent incident, ULA also pushed back the fifth and final launch of the U.S. Navy’s Mobile User Objective System (MUOS-5). That launch is now slated to take place no-earlier-than May 12, 2016.

“The ULA engineering team is continuing to review the data and has developed initial fault trees with our industry partners,” ULA said via a statement. “The review will thoroughly assess all flight and operational data to determine root cause and identify appropriate corrective actions prior to future flights.”