A Proton rocket lifts off from the Baikonur Cosmodrome. Credit: Roscosmos

A Proton rocket launched Sunday from the Baikonur Cosmodrome in Kazakhstan, boosting into a high-altitude orbit a classified Russian government satellite Western analysts believe is designed to eavesdrop on other countries’ radio transmissions.

The Proton rocket, made Russia’s Khrunichev State Research and Production Space Center, lifted off at 7:13 p.m. EDT (2313 GMT) Sunday from Baikonur, then headed east to propel its Russian government payload into orbit. Six hydrazine-fueled RD-276 engines powered the 191-foot-tall (58-meter) rocket off the launch pad with 2.5 million pounds of thrust.

Engine firings by the Proton rocket’s second and third stages continued powering the mission into space, then Breeze M upper stage, also made by Khrunichev, took over for a series of burns over the course of more than six hours, targeting a circular geostationary orbit some 22,000 miles (nearly 36,000 kilometers) over the equator.

The mission was the 429th flight of a Proton rocket since 1965. Russia plans to phase out the Proton rocket in the next few years.

The Breeze M upper stage released the satellite, which Russia’s government calls Luch 5X, into the proper orbit, according to Roscosmos, Russia’s space agency. Roscosmos said the Luch 5X satellite “will help develop advanced relay and communication technologies.”

Historically, Russia’s Luch family of satellites have performed civilian communications relay missions in support of the International Space Station and the earlier Mir space station. The launch Sunday was shrouded in secrecy, with no live video or details about the payload.

Independent analysts believe the Luch 5X name is a cover for a classified Russian satellite that is part of the Olymp-K program managed by the Federal Security Service, or FSB, intelligence agency or the Russian military. The first Olymp-K satellite launched on a Proton rocket in 2014 under a similar veil of secrecy.

After that satellite arrived in orbit, the U.S. military tracked it approaching multiple satellites in a series of maneuvers that took the Olymp-K spacecraft around the geostationary belt, rather than staying in a fixed position like most geostationary satellites. A 2020 report from Washington-based Center for Strategic & International Studies, or CSIS, said the first Olymp-K satellite was engaging in “suspicious” rendezvous and proximity operations activity in geostationary orbit.

“The satellite — known as Olymp-K or Luch — has attracted attention for shifting its position within the geosynchronous belt on a relatively frequent basis, occupying at least 19 different positions since its launch in September 2014,” the CSIS think tank said in 2020.

Then Olymp-K satellite first positioned itself between two satellites operated by the U.S. company Intelsat, then approached another Intelsat satellite in 2015. The French defense ministry accused Russia in 2018 of committing “an act of espionage” after the Olymp-K satellite approached a French-Italian military communications satellite in 2017, according to the CSIS report.

“Approaching satellites in GEO in this manner could allow for close inspection or potentially interception of their communication links,” CSIS said.

As of 2020, the Olymp-K satellite had approached 11 Intelsat satellites, four Eutelsat satellites, two SES satellites, and at least nine other satellites operated by Russia, Turkey, Pakistan, the United Kingdom, and the European Space Agency, CSIS said. The think tank said the Olymp-K satellite appeared to be “maneuvering around then GEO belt in a systematic, deliberate manner,” but there have been no public reports of any damage to other satellites.

Satellite watchers are ready to monitor the movements of the satellite launched Sunday, believed to be the second Olymp-K satellite, to see if it performs similar maneuvers to closely approach other spacecraft in geostationary orbit.

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Follow Stephen Clark on Twitter: @StephenClark1.