ILS Proton M
An ILS Proton M lifted off Aug. 28 from Baikonur Cosmodrome in Kazakhstan carrying Inmarsat's third Global Express satellite. Credit: ILS/Inmarsat

WASHINGTON — Launches of Russia’s Proton rocket will be postponed until the middle of May in order to replace faulty engines on several vehicles, a top Russian official said Jan. 28.

In a series tweets, Russian Deputy Prime Minister Dmitry Rogozin discussed a meeting he held Jan. 28 with representatives of the Voronezh Mechanical Plant, which makes engines used in the upper stages of the Proton and Soyuz launch vehicles.

Rogozin said in Russian-language tweets after the meeting that Proton launches will be delayed for several months to replace engines. “Three ‘Proton-M’ will be dismantled,” he wrote, to replace their second- and third-stage engines. “Launches of ‘Proton-M’ will be resumed in 3.5 months.”

The Rogozin comments come after a Jan. 20 meeting of Russian space industry executives organized by Roscosmos. During that meeting, Ivan Koptev, director of Voronezh, submitted his resignation voluntarily because of “underperformance and the quality of products,” according to a Roscosmos statement.

In a Jan. 11 release, Roscosmos blamed the Dec. 1 failure of a Soyuz launch vehicle carrying a Progress cargo spacecraft to foreign particles that entered the Soyuz’s third stage engine, causing a fire. The statement also indicated that defective assembly of the engine played a role in the failure. The engine, like the Proton upper stage engines, was manufactured by Voronezh.

The last Proton flight was the June 2016 launch of the Intelsat 31 communication satellite, which suffered a problem with the rocket’s second stage engine. The satellite still achieved its desired orbit when the rocket’s Breeze-M upper stage extended its burn.

Preparations were underway for Proton’s return to flight, carrying the EchoStar 21 satellite, when International Launch Services announced Dec. 28 that the launch would be delayed, but did not disclose the reason other than that it was not linked to the problem on the June launch. The launch date slipped several times prior to Rogozin’s announcement of the extended delay.

Neither Rogozin in his tweets, nor a Jan. 28 Roscosmos statement about his visit to Voronezh, discussed the reasons the engines would be replaced. Russian media previously reported that workers may have replaced materials used to manufacture the engines with alternatives that are less expensive but more likely to fail in flight.

The investigation into the engine issue is ongoing. “All those responsible for the substitution of technologies and documentation will be severely punished,” Rogozin tweeted.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...