Proton M/Briz M
Launch vehicle Proton M/Briz M
Launch site Baikonur, Kazakhstan
Date/Time 2011-08-18 0638 UTC
Description Upper stage failure
Cause Programming error
Payload Ekspress AM4
Desired orbit geostationary transfer orbit

International Launch Services, which markets the Proton for commercial launches, said on 19 August 2011 that "The Proton M launch vehicle performed nominally, and the ascent unit including the Breeze [Briz] M upper stage and the spacecraft separated at the appropriate time. Contact with the Breeze M and spacecraft was lost after the fourth burn of the Breeze M upper stage. Roscosmos specialists were able to locate the Breeze M Upper Stage. Efforts are now underway to establish contact with the Express-AM4 spacecraft."

Contact with the spacecraft, left in a useless orbit, was indeed established later. However, the satellite's operator, RSCC, declared the spacecraft a total loss and filed an insurance claim as a salvage mission appeared to make no economical sense.

A Russian Inter-Agency Commission completed its investigation of the off-nominal orbital injection of Ekspress-AM4. Based on its activities and analysis of the available data, the Commission concluded that in the process of formalising the Briz M operating timeline, the time interval to manipulate the gyro platform into position was made unduly short. This programming error, which reportedly consisted of a single erroneous input, resulted in an off-nominal orientation of the Briz M and, as a consequence, in injecting the SC into an off-design orbit.

All other Briz M systems have performed within specifications.

Last updated: 15 September 2011

Launch Failures Chronology