Just 51days after a stage separation failure threatened to put a wrinkle in the Protonrocket's launch schedule, the heavy-lifting Russian vehicle returned to spaceduring a Friday blastoff to loft three navigation satellites.
Liftoff ofthe 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 Glonasssatellites into the planned orbit.
Spacecraftseparation occurred on schedule about three-and-a-half hours after launch,according to the Russian Space Agency.
The Protonwas targeting an orbit about 12,000 miles high with an inclination ofapproximately 64.8 degrees.
Thesuccessful launch was the first flight of the Proton since a Sept.5 failure that was blamed on a faulty cable responsible for routing stageseparation commands to pyrotechnic bolts between the first and second stages ofthe booster.
The botchedlaunch was carrying a Japanese telecommunications satellite under the auspicesof International Launch Services, the international firm that markets theProton to commercial customers.
Aninvestigation commission cleared the rocket for future flights, and ILS plansto resume commercial missions with the launch of SIRIUS 4, a Europeancommunications craft, at 2240 GMT (5:40 p.m. EST) on Nov. 17.
The Kazakhgovernment placed a ban on further Proton launches from Baikonur after lastmonth's rocket crash, but the moratorium was lifted earlier this week.Kazakhstan is seeking a $60 million payment from Russia for damages from theSeptember failure, according to the Novosti news agency.
Thesatellites launched aboard the Proton Thursday will begin missions to replenishRussia's Global Navigation Satellite System constellation, that nation'scounterpart to the U.S. Global Positioning System.
The Glonassfleet provides users with precise information on their location, velocity andtime. Civilian users can use Glonass data to determine elevation and positioningdata within about 200 feet, according to the Russian Space Agency.
The Glonassconstellation is divided among three orbital planes, each consisting of up toeight satellites. Ten spacecraft in the fleet are currently operating, notincluding the satellites launched Friday. Three more craft in the Glonass fleetare temporarily turned off for maintenance, according to a Russian Space AgencyWeb site.
The activesatellites have been operational for an average of nearly two-and-half years.The flotilla includes two generations of Glonass spacecraft models withlifetimes of three and seven years.
Russianofficials expect further launches will expand the Glonass program to its fullcomplement of 24 satellites, which would provide uninhibited global coverage tomilitary and civilian users.
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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 SpaceflightNow.com and on Twitter.