Three new satellites were launched by Russia on Sunday on the first leg of their mission to rejuvenate the country's system of space-based navigation that is relied upon by a host of military and civilian users.

The trio is the latest addition to the Global Navigation Satellite System, or GLONASS, which is the Russian equivalent of the U.S. Air Force's Global Positioning System and Europe's fledgling Galileo program.

A Proton rocket gave the spacecraft a successful Christmas Day ride to space after lifting off from Kazakhstan's Baikonur Cosmodrome at 0507 GMT (12:07 a.m. EST).

The launcher included a Block-DM upper stage that performed several burns to place the three craft in the desired circular orbit almost 12,000 miles in altitude and inclined 64.8 degrees before releasing them into space at 0839 GMT (3:39 a.m. EST), a report from RIA Novosti said.

The payload consisted of two upgraded GLONASS satellites, which feature longer service lives of seven years, while also substantially increasing the precision of positioning data produced using the constellation. The third spacecraft is an older model with an anticipated lifetime of three years.

Once operational, each 3,000-pound satellite will enter service to provide exact positioning, velocity, and timing information to millions of users around the world, including the Russian armed forces.

Discounting Sunday's launch, the GLONASS fleet currently includes just 14 active satellites, but one craft was at least temporarily taken out of service earlier this month according to an online status report.

The system is designed around three orbital planes, with each intended to contain eight satellites. Officials hope 18 spacecraft will be in space by 2007, allowing the group to become fully operational, followed by reaching the system's full complement of 24 satellites by 2010, the Itar-Tass news agency reported.

The primary customers of GLONASS data are found in the air and marine traffic and ground transportation industries. Other users such as scientists, law enforcement agencies, and outdoor enthusiasts also often look to space for navigation information.

The next Proton launch is scheduled for 0228 GMT Thursday (9:28 p.m. EST Wednesday) to haul the AMERICOM 23 communications satellite into orbit for U.S-based operator SES AMERICOM. The International Launch Services-managed mission, originally planned for early December, was delayed to replace a suspect gyroscope in the rocket's control system.