SPACE.com -- Ukrainian Zenit Rocket Returns to Flight

Russia launched a secretive military satellite aboard a Zenit rocket Friday, marking the first flight of the Ukrainian-built booster since it suffered a catastrophic failure on a sea-going launch pad in January.

Liftoff of the Zenit 2M rocket was at 1000 GMT (6:00 a.m. EDT) from launch pad 45 at the Baikonur Cosmodrome in Kazakhstan. The two-stage launcher successfully deployed its military payload into orbit a few minutes later, according to Russian media reports.

The payload is called Kosmos 2428 under the Russian military's naming scheme for classified satellites.

The Zenit 2M version of the venerable rocket was flying on its first mission Friday. The updated booster includes an upgraded control system and modernized engines that will be used commercially by Sea Launch for flights from Baikonur beginning early next year.

Friday's mission was the also the first use of the first stage's RD-171M engine since Sea Launch's Zenit 3SL rocket exploded on its launch platform in January. The incident resulted in the loss of the booster and the NSS 8 satellite, a multipurpose communications satellite designed to serve customers in a wide swath stretching from Europe to India.

Investigators traced the cause of the failure to a piece of metallic debris lodged inside the engine's liquid oxygen turbopump, according to a Sea Launch statement.

"This object ignited and burned as a result of friction-induced heat," the statement said. "The combustion set off a string of events that led to the destruction of the (liquid oxygen) pump, RD-171M engine and ultimately the Zenit 3SL."

The RD-171M engine burns rocket-grade kerosene and liquid oxygen during the first stage burn, which lasts about two-and-a-half minutes. The engine consists of four thrust chambers and four nozzles.

A joint government commission headed by Russia and Ukraine determined all RD-171M engines already manufactured were free of the debris, Sea Launch said.

Sea Launch expects to resume flights in October. Repairs to the company's damaged Odyssey launch platform are already underway at a Canadian shipyard.

The Zenit last flew from Kazakhstan in June 2004. Friday's military launch was postponed from early this year due to technical problems, the Russian news agency Interfax reported.

Sea Launch plans to begin launching Zenit rockets from Baikonur early next year under the company's Land Launch program, which aims to capture a portion of the launch market for mid-size communications satellites.

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