The latest additions to Russia's indigenous satellite navigation system successfully arrived in orbit Monday after a nearly four-hour ride aboard a Proton rocket.

Three 3,000-pound satellites were packaged atop the Proton launcher. The Christmas delivery was right on target, and the rocket reached the correct orbit about 12,000 miles high with an inclination of around 64.8 degrees.

Liftoff of the Proton K rocket was at 2018 GMT (3:18 p.m. EST) from Complex 81 at the Baikonur Cosmodrome in Kazakhstan.

The booster included a Block DM upper stage that conducted two burns to deliver the satellite trio into the proper orbit.

The three spacecraft are upgraded members of Russia's Global Navigation Satellite System, the nation's counterpart to the U.S. Global Positioning System.

The Glonass M satellites are designed to operate for up to seven years, an improvement over earlier Glonass craft that could only last three years in space.

Upgraded Glonass spacecraft also feature a second civilian navigation channel and increased accuracy for both military and private users. After the satellites are pressed into service, they will provide horizontal and vertical positioning data within about 200 feet to worldwide users, according to the Russian Space Agency.

Glonass satellites also allow users to determine velocity and their exact time, according to the Itar-Tass news agency.

The Glonass fleet currently consists of 11 operational spacecraft, with five more at least temporarily switched off, according to an online status report. Those tallies do not include the satellites launched Monday.

When fully deployed, the constellation is designed to operate in three orbital planes, each with eight satellites. The system now fills two planes, but a third remains empty, according to a Russian Space Agency Web site.

Russian officials are planning more Glonass launches in 2007 and 2008 to fill the gaps in the fleet, and there could be 18 active spacecraft in orbit within about one year. The system is scheduled to reach its full complement of 24 satellites by 2009, according to Itar-Tass news reports.

Monday's flight marked the 62nd space launch to reach Earth orbit this year. At least one more launch is scheduled for Wednesday, when a Russian Soyuz rocket will carry a European science satellite into space.

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