NESC also called for NASA and Orbital to develop a system-level model of the fairing deployment system to identify and evaluate additional risk factors and potential failure scenarios. Agency managers rejected the recommendations on cost and schedule grounds.

“There was a very overt discussion of what was the risk that we believed was in there versus the risk and the cost that would be tied up with a very long launch delay,” says NASA Chief Engineer Mike Ryschkewitsch.

Ryschkewitsch and Jim Norman, director for launch services in the HEO mission directorate, stress that there is no way to duplicate a shroud separation of the size in question on the ground, so flightworthiness decisions must be based on analysis, engineering judgment and experience.

Norman says NASA engineers have good insight into Orbital's engineering work on the Antares shroud separation flightworthiness. “Significant progress has been made,” he says. “We're on a good path. We are not yet done.”

Under the COTS contract, Orbital Sciences will have the final say on the first Antares launches. NASA won't start having a go-no-go decision role until operational cargo missions begin under the company's $1.9 billion, eight-flight Commercial Resupply Services contract, Norman says.