Russia launched a Proton rocket Thursday night with an early warning satellite to defend the country against missile attacks, news reports said.

The heavy-lifting launcher blasted off at 2359 GMT (7:59 p.m. EDT) from the Baikonur Cosmodrome in Kazakhstan, according to Khrunichev, the rocket's prime manufacturer.

The Proton's Block DM upper stage was programmed to guide the top secret payload into a circular geosynchronous orbit about 22,300 miles high. The rocket stage deployed the satellite on schedule at 0737 GMT (3:37 a.m. EDT), Khrunichev said in a written statement.

The spacecraft will help warn Russian military forces of worldwide missile launches, according to the Novosti news agency.

Military officials were expected to rename the satellite Kosmos 2440 as part of the defense ministry's space nomenclature.

The launch was the first mission of the Proton rocket since a different version of the booster left the AMC 14 communications satellite in a useless orbit during a flight in March.

But this week's launch used an older Proton model, including a different upper stage than the Breeze M blamed for the March failure.

Investigators faulted a ruptured exhaust gas duct between the gas generator and a turbo pump inside the Breeze M main engine. The burst pipe led to an early shutdown of the engine, according to International Launch Services, the Russian-owned, U.S.-based company marketing the Proton to commercial customers.

Engineers replaced the gas duct on the next Breeze M stage with a conduit with thicker walls to prevent similar problems from happening again. Similar new pipes will be added to all future Breeze M stages, ILS officials said.

ILS cleared the Breeze M for return to flight earlier this month, and the next commercial Proton launch is expected later this summer. The Proton will deliver the Inmarsat 4-F3 mobile broadband communications satellite to orbit.

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