Just 51 days after a stage separation failure threatened to put a wrinkle in the Proton rocket's launch schedule, the heavy-lifting Russian vehicle returned to space during a Friday blastoff to loft three navigation satellites.

Liftoff of the Proton was at 0735 GMT (3:35 a.m. EDT) from Baikonur Cosmodrome, Kazakhstan. A Block DM upper stage fired twice to place the trio of Glonass satellites into the planned orbit.

Spacecraft separation occurred on schedule about three-and-a-half hours after launch, according to the Russian Space Agency.

The Proton was targeting an orbit about 12,000 miles high with an inclination of approximately 64.8 degrees.

The successful launch was the first flight of the Proton since a Sept. 5 failure that was blamed on a faulty cable responsible for routing stage separation commands to pyrotechnic bolts between the first and second stages of the booster.

The botched launch was carrying a Japanese telecommunications satellite under the auspices of International Launch Services, the international firm that markets the Proton to commercial customers.

An investigation commission cleared the rocket for future flights, and ILS plans to resume commercial missions with the launch of SIRIUS 4, a European communications craft, at 2240 GMT (5:40 p.m. EST) on Nov. 17.

The Kazakh government placed a ban on further Proton launches from Baikonur after last month's rocket crash, but the moratorium was lifted earlier this week. Kazakhstan is seeking a $60 million payment from Russia for damages from the September failure, according to the Novosti news agency.

The satellites launched aboard the Proton Thursday will begin missions to replenish Russia's Global Navigation Satellite System constellation, that nation's counterpart to the U.S. Global Positioning System.

The Glonass fleet provides users with precise information on their location, velocity and time. Civilian users can use Glonass data to determine elevation and positioning data within about 200 feet, according to the Russian Space Agency.

The Glonass constellation is divided among three orbital planes, each consisting of up to eight satellites. Ten spacecraft in the fleet are currently operating, not including the satellites launched Friday. Three more craft in the Glonass fleet are temporarily turned off for maintenance, according to a Russian Space Agency Web site.

The active satellites have been operational for an average of nearly two-and-half years. The flotilla includes two generations of Glonass spacecraft models with lifetimes of three and seven years.

Russian officials expect further launches will expand the Glonass program to its full complement of 24 satellites, which would provide uninhibited global coverage to military and civilian users.