Upper stage from failed Russian rocket to make uncontrolled re-entry

The troubles with the long-in-development Angara A5 continue.

Eric Berger – Jan 4, 2022 4:02 PM | 155

An Angara A5 rocket launches in December 2020 on its second test flight. Credit: Russian Ministry of Defense

The Russian space program has spent more than two decades developing the Angara family of rockets, and government officials have expressed high hopes for the Angara A5 heavy lift variant. It is hoped that the Angara A5 rocket can replace the venerable Proton booster, which is more than half a century old and in recent years has had reliability issues.

But the long-running development program has been slow. The Angara A5 finally made its debut in 2014, successfully lofting a 2-ton mass simulator into geosynchronous orbit. But then, six years passed before a second development flight in December 2020. This flight was again successful, with the rocket putting a 2.4-ton mass simulator into orbit.

Why did it take so long between test flights? Costs, production issues, and a lack of demand all seem to have been factors. Although the Russian government has not been forthcoming, the expense of building the Angara A5 was probably the biggest factor. The Russian space program had hoped to make the Angara A5 competitive with SpaceX's Falcon 9 rocket for commercial launches, but Russian media reported that Angara production costs to date have been about $100 million per vehicle.

In December, the Angara A5 rocket appeared ready to get back on track as technicians prepared it for a third and final development flight. Following this flight, Russia planned to begin flying military payloads on the Angara A5 and presumably would also use it to compete for commercial satellite launch contracts.

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This configuration of the Angara rocket contained the same first stage as the first two flights, consisting of a single "Universal Rocket Module" core powered by an RD-191 engine, with four additional "URM" cores serving as attached boosters. However, for its third demonstration flight, the Angara A5 used a new upper stage named "Persei."

With this modernized upper stage, Russian officials hoped to move away from the toxic propellants—dinitrogen tetroxide and hydrazine—that power the Briz-M upper stage. Persei, by contrast, uses liquid oxygen and kerosene.

For its third test flight, the Angara A5 vehicle lifted off from the Plesetsk Cosmodrome in northern Russia on December 27, again carrying a dummy payload. The core stage and boosters performed nominally, as did a second stage. After the Persei upper stage and its mass simulator deployed, its RD-0124 engine performed a nominal initial burn. But a second burn to put the payload into a higher, stable orbit failed.

Curiously, Russian officials nonetheless celebrated the Angara rocket's test launch as a great achievement. Multiple Russian news sources heralded the success of the rocket's launch a week ago.

Two days after the launch, even, the state-controlled Russian news service RT published an article with a headline stating that the Persei upper stage would significantly improve the performance of the Angara A5 vehicle. However, the article mentioned that Russian space chief Dmitry Rogozin was still waiting for the upper stage to relight.

"Dmitriy Rogozin congratulated the military on the successful launch of the new booster, noting that we are still waiting for the Persei upper stage to work," the article states. They're still waiting. The Persei upper stage, of course, was never going to relight, and Russian officials had to know this.

The proof is in the sky. This Persei stage, tracked as IPM 3/Persey, is now well below 200 km and will likely make an uncontrolled re-entry into Earth's atmosphere on Wednesday. Hopefully, it will do so over an ocean.