Why did the Proton fall?

An interdepartmental commission analyzing the possible causes of an abnormal launch of the Proton-M launch vehicle considers the most likely cause of the accident to be the destruction of the turbopump bearing in the third stage steering engine, but does not exclude the possibility of sabotage. This was announced by the chairman of the commission, first deputy general director of TsNIIMash, Alexander Danilyuk.

The Proton-M launch vehicle with the Briz-M upper stage and the Express-AM4R communications satellite launched from the Baikonur Cosmodrome on May 16. During the operation of the third stage of the rocket, an emergency situation arose and the spacecraft was not launched into orbit. By decision of Roscosmos and the Ministry of Defense of the Russian Federation, an Interdepartmental Commission was created to investigate the accident, which included 24 experts from Roscosmos, the Ministry of Defense, ORKK, the Keldysh Research Center, NPO Tekhnomash, the Central Research Institute of the Aerospace Defense Forces and other organizations.

Working groups within the commission analyze telemetric information and data from external measurements of the rocket’s trajectory, design and technological documentation, manufacturing processes, testing, acceptance, transportation, storage and preparation of the rocket for launch. The commission's experts work at Baikonur, in design bureaus, manufacturing plants, and in flight control centers.

Based on the results of the preliminary analysis, the commission left for further consideration four versions of the cause of the accident, all of them related to the operation of the third stage steering motor: destruction of the bearing assembly of the turbopump unit; depressurization of the fuel supply line; foreign particles entering the fuel flow regulator or stabilizer; clogging of the filter along the fuel line. Based on the results of work at the Design Bureau of Chemical Automatics (KBHA) and at the Voronezh Mechanical Plant, where steering motors are produced, as well as at the rocket and space plant at the State Research and Production Space Center named after. M.V. Khrunichev “the commission did not identify any violations that could have been the direct cause of the accident,” said the head of the MVK.

Based on materials from the Roscosmos press service