Sunday, February 7, 2016

Russia Launches Its Latest GLONASS-M Navigation Satellite into Orbit

A Russian Soyuz-2.1b rocket has thundered into space from Site 43/4 at the Plesetsk Cosmodrome in Archangelsk Region, to deliver the latest GLONASS-M satellite for the country’s homegrown GLObal NAvigation Satellite System (GLONASS). Credit: Russian Ministry of Defense

A Russian Soyuz-2.1b rocket has thundered into space from Site 43/4 at the Plesetsk Cosmodrome in Archangelsk Region, to deliver the latest GLONASS-M satellite for the country’s homegrown GLObal NAvigation Satellite System (GLONASS). Liftoff took place as planned at 7:21 p.m. EST on Saturday Feb. 6 (0:21 GMT on Sunday Feb. 7). “All the pre-launch operations and the rocket launch were normal. Ground-based automatic control aids monitored the space vehicle launch and flight," Russian Defense Ministry said.

The launch of the mission was initially scheduled for Dec. 28, 2015, but was postponed two times due operational difficulties. The launch campaign started in late-December 2015 with first checks of the satellite. In mid-November, the spacecraft was delivered to Plesetsk.

Final preparations and checkouts were carried out during an eight-hour countdown that preceded the liftoff. The launch vehicle was loaded with propellants and the Automated Countdown Sequence started, handing over control of the launch to the onboard computers.

After liftoff, the Soyuz-2.1b rocket commenced a short vertical climb, lasting only few seconds before it started heading south-east. The vehicle’s four boosters were jettisoned nearly two minutes into the flight. Next, the rocket’s core stage burned its engine for approximately two minutes and 50 seconds, before separating from the Fregat-M upper stage. Nearly three and a half hours later, the satellite was injected into a medium Earth orbit (MEO).

The spacecraft, named GLONASS-M No. 51, received designation Kosmos 2514 when it reached the targeted orbit. It will replace the Kosmos 2419 satellite, launched in 2005.

GLONASS-M satellites, also known as Uragan-M, are the second generation of Uragan satellite design used as part of the Russian GLONASS radio-based navigation system. Typical GLONASS-M spacecraft, developed by Reshetnev Information Satellite Systems (ISS Reshetnev) is about 7.87 by 12.14 feet (2.4 by 3.7 meters) and has a launch mass of 1.4 tons. With a total power of 1250 W, these satellites are designed to operate for up to seven years. Equipped in three caesium clocks, GLONASS-M can provide accurate timing reference needed to generate navigation data. First spacecraft in the series was launched in December 2003, while the final launch is expected in late 2017.

Operated by the Russian Aerospace Defence Forces, GLONASS is currently the only global alternative to the U.S. GPS in operation that has global coverage of comparable precision. The development of the program started in 1976 and the first launch was conducted in 1982. It took over a decade for the system to become operational as it struggled with funding issues. In December 1995, the system became fully operational for the first time as the constellation consisted of 24 satellites needed to provide global coverage.

GLONASS provides real time position and velocity determination for military and civilian users. The satellites are located in middle circular orbit at 11,900 miles (19,100 kilometers) altitude with a 64.8 degree inclination and a period of 11 hours and 15 minutes. It provides an accuracy of 328 feet (100 meters) as part of the public segment and 33 to 66 feet (10 to 20 meters) for the military purposes.

The system operates in three orbital planes, with eight evenly spaced satellites on each. While a fully operational constellation with global coverage needs 24 satellites, 18 are necessary to cover the whole territory of Russia.

The Soyuz-2.1b rocket that was employed in Saturday’s launch is an upgraded version of a three-stage carrier Soyuz-2 booster. The 151 feet (46.1 meters) tall launch vehicle with a total mass of 672,000 lbs. (304,814 kg) is designed to put satellites into a variety of orbits. The Soyuz-2.1b is capable of putting up to 18,100 lbs. (8,210 kg) into a low-Earth orbit (LEO), 10,800 lbs. (4,899 kg) into a Sun-synchronous orbit (SSO) and 7,170 lbs. (3,252 kg) into a geostationary transfer orbit (GTO). The first launch of this version took place from Plesetsk on July 26, 2008, with a classified military payload.

This launch vehicle uses four RD-107A engines for liftoff, burning for about 2 minutes. The first stage, 88.9 feet (27.1 meters) long and 9.7 feet (2.95 meters) in diameter, is equipped in one RD-108A engine. The rocket’s second stage has a length of 22 feet (6.7 meters) and is 8.7 feet (2.66 meters) in diameter. The 2.1b version has an upgraded engine RD-0124 with improved performance to the second stage.

For Saturday’s mission, the Soyuz-2.1b rocket was used in a configuration with a Fregat-M third stage. This upper stage is 4.9 feet (1.5 meters) long and has 11 feet (3.35 meters) in diameter. Its S5.92 engine burns for about 18 minutes. Fregat-M is responsible for the orbital insertion of the satellite. However, it could be also used as an escape stage to send space probes onto interplanetary trajectories. Fregat stages are currently used as the fourth stage of some Soyuz-FG launch vehicles.

Saturday’s launch was the second orbital flight for Russia, the first liftoff from Plesetsk and also the first Soyuz mission in 2016. The country plans its next launch for Feb. 16, when a Rokot rocket is slated to orbit an ESA Earth observation satellite, named Sentinel-3A.

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