The satellites will help keep Globalstar's two-way voice and data service going through the 2020s for the company's subscribers in 120 countries.
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The mission completes Globalstar's second-generation satellite fleet, which began launching in 2010. Four Soyuz launches sent 24 Globalstar satellites into orbit, supplementing and replacing the Lousiana-based company's first-generation satellites, most of which launched from 1998 to 2000.
The new satellites were attached to a specially-designed dispenser during the launch, and the craft were scheduled to separate in sequence. Two satellites mounted to the top of the dispenser were to separate first, followed by the remaining four payloads.
The separation was due to conclude at 1744 GMT (12:44 p.m. EST). Each satellite weighs about 1,543 pounds.
After liftoff from the Baikonur Cosmodrome, the mission's Soyuz rocket propelled a Fregat upper stage and the six satellites on a suborbital trajectory. Burning storable hypergolic propellant, the Fregat fired twice, first to inject the satellites in a temporary parking orbit, then to circularize the orbit at an altitude of approximately 572 miles and an inclination of 52 degrees.
The satellites will use on-board propulsion to raise their orbits to an altitude of 878 miles and enter the Globalstar constellation.
The vehicle is now in an elliptical parking orbit, and a second burn will come in a little over an hour to circularize the orbit. Separation of the Globalstar spacecraft is expected at about 1744 GMT (12:44 p.m. EST).
The engines of the core stage and strap-on boosters will ignite beginning at an intermediate thrust level at T-minus 20 seconds, ramping up to full thrust moments before liftoff.
Here are some statistics on today's launch:
The launch is rescheduled for Wednesday at 1604 GMT (11:04 a.m. EST).
Check out video and photos of the Soyuz rollout to the launch pad Saturday in snowy weather conditions.
Tuesday's launch of the fourth and final batch of 24 second-generation satellites for Globalstar Inc. will keep the Louisiana-based company's communications services active through the 2020s.
The launch follows three successful Soyuz flights with the new-generation Globalstar satellites in 2010 and 2011, each of which sent six spacecraft into orbit.
Globalstar subscribers in more than 120 countries use the satellites to make mobile phone calls and data transmissions, especially in rural zones where terrestrial coverage is spotty or non-existent.
The Russian Soyuz 2-1a booster moved to its launch pad Saturday at the Baikonur Cosmodrome in Kazakhstan, and liftoff is set for 1620 GMT (11:20 a.m. EST), or 10:20 p.m. local time at the Central Asia launch base.
The venerable Soyuz rocket, flying in a modernized configuration with a digital control system, will rise from the launch pad and pitch east from Baikonur, racing into the upper atmosphere before shedding four strap-on liquid-fueled boosters.
The rocket's core stage, called the second stage on the Soyuz, will shut down less than 5 minutes after liftoff, followed seconds later by release of the launcher's 13.4-foot-diameter nose shroud.
The Soyuz third stage's RD-0110 engine is programmed to fire for about 4 minutes before separation of the rocket's Fregat upper stage, which will inject the mission's six satellite passengers into low Earth orbit.
The Fregat upper stage, fueled by storable hydrazine propellant, will burn three times during the mission. The first ignition will place the stage and the Globalstar satellites in a temporary parking orbit, and a second firing will place the payloads in a circular 572-mile-high orbit with an inclination of 52 degrees, where a specially-designed dispenser will deploy the spacecraft.
Two satellites mounted on top of dispenser will separate first, followed by the four other craft moments later.
The separation sequence will complete at about 1800 GMT (1 p.m. EST).
A third Fregat burn later Tuesday will guide the defunct rocket stage to a re-entry over the South Pacific Ocean.
The launch was arranged through a contract with Starsem, which oversees commercial Soyuz flights from the Baikonur Cosmodrome. Starsem is partly-owned by Arianespace, a market-leading launch services firm based in France.
The Globalstar satellites will raise their altitude to about 878 miles over the next few weeks, where they will join the company's fleet of operational spacecraft.
Two of the 1,543-pound spacecraft will enter service as soon as this month, and the other newly-launch satellites will drift into position within the Globalstar constellation in the coming months. Globalstar satellites are divided among eight orbital planes to evenly spread the spacecraft across the globe.
Thales Alenia Space assembled the satellites in Rome and built their communications equipment in Toulouse, France.
Globalstar ordered the second-generation satellites to replace the company's aging first-generation fleet, which was primarily launched from 1998 to 2000.
The new satellites also restored Globalstar's duplex, or two-way, communications service, which was degraded due to problems with S-band antennas on the company's first-generation satellites. Globalstar officials say customers already see a major improvement in the two-way service, and the six satellites to launch Tuesday will ensure further improvements.
Globalstar has ordered another six identical satellites from Thales for launch in 2015 to replenish the constellation and keep the system operational up to 2030.