PARIS — The May 29 statement by Roscosmos on the May 16 Proton rocket failure confirmed initial suspicions of a third-stage engine issue but otherwise left many questions unanswered about the failure’s origin.

Here is the full-text version of the best translation we have found:

The Roscosmos Agency Commission investigating the failed launch of the Proton-M with the Centenario spacecraft May 16, 2015 from Baikonur Cosmodrome announced the outcomes of its work.

The commission members (representatives of the customer, Roscosmos and the Russian Federation Ministry of Defense, heads of industry R&D institutes and production facilities) performed an analysis of the Proton-M and its components manufacturing process, the process of acceptance, transportation, testing and processing, as well as telemetry and ranging information.

Conclusion: Abnormal termination of the Proton-M flight was caused by the Stage 3 Steering Engine failure due to increased vibration loads occurring as a result of the imbalance of the turbo pump unit rotor caused by the degradation of its material properties at high temperatures, and improper balancing.

By the order of Roscosmos head Igor Komarov, Khrunichev Space Center and its subsidiaries are developing an action plan to address the causes of the accident, which includes:

Changing materials used for the turbo pump rotor shaft manufacturing;

Revision of the turbo pump rotor balancing techniques;

Upgrade of the steering engine turbo pump mount to the main engine frame, and others.

The Commission also identified a number of deficiencies in the enterprises’ Quality Management System. An action plan to address these will be developed within a month.

The date of the Proton-M next launch will be announced by Roscosmos in June 2015.