The ILS board met last week in Moscow with members of the Russian State Commission that investigated the Nov. 26 launch of a Proton/Block DM vehicle from Baikonur Cosmodrome in Kazakhstan. The failure left the ASTRA 1K satellite in a lower-than-planned orbit. The ILS board also met with representatives from Khrunichev State Research and Production Space Center, RSC Energia and hardware subcontractors.

The State Commission exonerated the three-stage Proton vehicle built by Khrunichev. The failure was attributed to contamination in engine components of the Block DM upper stage, made by Energia. The propellant used was not cited as a potential root cause.

The fuel used in the Block DM, a synthetic kerosene known as syntin that was developed by Energia, was tested before launch as part of normal preflight processing, and after the failure. The fuel met all Russian government specifications.

The anomaly occurred at the start of the second Block DM main engine burn. There was excessive fuel in the main engine when it was ignited, which led to extraordinarily high temperatures that destroyed the engine, the commission found.

In the final report, the State Commission was unable to pinpoint a single root cause for the failure. It identified two possible scenarios for the fuel build-up, both attributed to contamination that interfered with the normal operation of fuel metering components, resulting in excess fuel in the gas generator.

In one scenario, 'stray particles' clogged the manifolds through which fuel is drained from the starting-fluid feed line after the first burn. In the other, the contaminants clogged a valve designed to supply fuel to the gas generator injector, causing the valve to leak.

"We may never know the root cause of the contamination in the Block DM engine," said Eric Laursen, ILS vice president and chief engineer as well as chairman of the ILS review board. "It may have been introduced during the manufacturing process, or following acceptance of the engine, and could have affected the engine at any time in the flight."

The ILS review board is continuing its evaluation of the two scenarios, pending the receipt of additional data from the State Commission this week. The review board will also evaluate a corrective action plan being developed by Energia to address the State Commission's concerns. The State Commission made several recommendations in such areas as Block DM testing and inspection for contaminants. The corrective action plan is due to the commission by mid-February. The commission in turn will review the plan to determine the validity and sufficiency of the proposed remedies.

"Only when the ILS review board is confident that a robust plan is in place, to ensure quality in newly manufactured as well as existing hardware, will commercial flights using the Block DM upper stage resume," Laursen said.

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