Ukrainian Zenit Rocket Returns to Flight

Sea Launch Rocket Explodes During Launch
Sea Launch's Zenit-3SL vehicle stands erect on the launch pad in this image taken before its failed Jan. 30, 2007 liftoff. (Image credit: Sea Launch.Larry Trotter.)

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

Liftoff of the Zenit 2Mrocket was at 1000 GMT (6:00 a.m. EDT) from launch pad 45 at the BaikonurCosmodrome in Kazakhstan. The two-stage launcher successfully deployed itsmilitary payload into orbit a few minutes later, according to Russian mediareports.

The payload is calledKosmos 2428 under the Russian military's naming scheme for classifiedsatellites.

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

Friday's mission was thealso the first use of the first stage's RD-171M engine since Sea Launch's Zenit3SL rocket explodedon its launch platform in January. The incident resulted in the loss of thebooster and the NSS 8 satellite, a multipurpose communications satellitedesigned to serve customers in a wide swath stretching from Europe to India.

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

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

The RD-171M engine burnsrocket-grade kerosene and liquid oxygen during the first stage burn, whichlasts about two-and-a-half minutes. The engine consists of four thrust chambersand four nozzles.

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

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

The Zenit last flew fromKazakhstan in June 2004. Friday's military launch was postponed from early thisyear due to technical problems, the Russian news agency Interfaxreported.

Sea Launch plans to beginlaunching Zenit rockets from Baikonur early next year under the company's LandLaunch program, which aims to capture a portion of the launch market formid-size communications satellites.

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Stephen Clark is the Editor of Spaceflight Now, a web-based publication dedicated to covering rocket launches, human spaceflight and exploration. He joined the Spaceflight Now team in 2009 and previously wrote as a senior reporter with the Daily Texan. You can follow Stephen's latest project at and on Twitter.