|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|
|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