Proton M/Briz M
Launch vehicle Proton M/Briz M
Launch site Baikonur, Kazakhstan
Date/Time 2012-12-08 1313 UTC
Description Upper stage failure
Cause Adverse thermal conditions
Payload Yamal 402
Desired orbit geostationary transfer orbit

International Launch Services, which markets the Proton for commercial launches, issued details regarding the most probable root cause and corrective actions presented to the ILS Failure Review Oversight Board (FROB) concerning the Yamal 402 Proton launch anomaly which occurred on 8 December 2012.

Yamal 402, built by Thales Alenia Space for Russian satellite operator, Gazprom Space Systems, was successfully manoeuvred to its orbital position and was declared fully operational on 8 January 2013 after completing its on orbit tests.

The members of the FROB agreed with the findings of the Russian investigation that the most probable cause of the Yamal 402 Proton launch anomaly was due to a combination of adverse conditions which affected the operation of the Briz M main engine during the startup of the third burn.

The combination of adverse conditions were predominantly thermal in nature and affected the conditions at the oxidiser inlet line to the Briz M main engine prior to the third burn ignition and resulted in a large volume of oxidiser gas (rather than liquid oxidiser) at the engine inlet, exceeding the Briz M main engine specifications. The volume of gas was ingested by the Briz M turbopump at the start of the third burn, leading to over-speed of the oxidiser turbopump bearing without the cooling normally supplied by liquid oxidiser. The over-speed damaged the bearing, which eventually led to the premature shutdown of the fourth burn. The adverse thermal conditions were due to higher than previously recorded propellant temperatures at lift-off combined with higher than previously recorded thermal soak-back of engine heat to the Briz M prior to the third burn.

Several corrective actions will be implemented, and include management of both satellite and Briz M thermal requirements to ensure adequate margin to prevent future recurrence of this anomaly. No Briz M hardware modifications are required.

Last updated: 16 February 2013

Launch Failures Chronology