Sunday, May 29, 2016

Soyuz-2.1b Blasts Off from Plesetsk with Russia’s Latest GLONASS-M Navigation Satellite

Soyuz-2.1b blasts off from Plesetsk with Russia’s latest GLONASS-M navigation satellite on May 29. Credit: mil.ru

Russia has successfully launched on Sunday, May 29, its newest GLONASS-M spacecraft in order to replenish the country’s homegrown navigation satellite system. The spacecraft took to the skies atop a Soyuz-2.1b rocket at exactly 4:45 a.m. EDT (8:45 GMT) from the Site 43/4 at the Plesetsk Cosmodrome in northern Russia.

"On Sunday, at 11:45 a.m. Moscow time [08:45 GMT] a squad of the Russian Space Forces of Russian Aerospace Forces successfully carried out a launch of a Soyuz-2.1b carrier rocket with the navigation satellite Glonass-M," the press service of the Russian Defense Ministry said.

Due to the military nature of this mission, very little information were provided by the authorities and there was no live webcast of the launch available. The military hasn’t also disclosed the cause of the postponement of the liftoff from May 21 to May 29.

The satellite, designated GLONASS-M No. 53, was shipped to Plesetsk on April 22 aboard a cargo aircraft IL-76.

Countdown for the mission started eight hours before the planned liftoff. During the last hours before launch, final preparations and checkouts were carried out. The rocket was loaded with propellants and the control of the launch was handed over to the onboard computers.

Soyuz-2.1b commenced its mission with a short vertical ascent lasting only several seconds until it started heading southeast. Nearly two minutes later, the rocket’s four boosters were jettisoned.

Approximately three minutes into the flight, the payload fairing separated from the launch vehicle, exposing the satellite. The rocket’s core stage was firing its engine until it was detached from Soyuz about four and a half minutes after launch. Then, the third stage took over control of the flight lasting about four minutes, when it was separated from the launch vehicle.



About nine minutes into the flight, the rocket’s Fregat-M upper stage ignited its engine to start its three-hour flight tasked with delivering the spacecraft into designated orbit at an altitude of approximately 11,800 miles (19,000 km), inclined 64.77 degrees toward the Equator. After reaching its targeted orbit, the satellite will complete several weeks of commissioning and testing before entering regular service.

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. A typical GLONASS-M spacecraft, developed by the Reshetnev Information Satellite Systems (ISS Reshetnev) and operated by the Russian Aerospace Defence Forces, is about 7.87 by 12.14 feet (2.4 by 3.7 meters) and has a launch mass of some 1.4 metric tons.

With a total power of 1,250 watts, these satellites are designed to operate for up to seven years. Equipped with three caesium clocks, they can provide the accurate timing that is required for navigational purposes. Satellites of this type broadcast four FDMA signals in the L1 and L2 frequency bands.

The first spacecraft in the series was launched in December 2003, while the final satellite is expected to be sent aloft in late 2017.

GLONASS provides real-time position and velocity determination for both military and civilian users. The satellites are located in a middle circular orbit at about 11,900 miles (19,100 kilometers) altitude with a 64.8-degree inclination at 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 military purposes. 

The system operates in three orbital planes, with eight evenly-spaced satellites on each. A total of 24 satellites are required to guarantee global coverage, while 18 are necessary to cover the territory of Russia.

GLONASS is currently the only global alternative to the U.S. GPS in terms of operational capability and global coverage. The development of the program started in 1976 with the first launch being conducted in 1982. It took more than a decade for the system to become operational as it struggled with funding issues. In December of 1995, the system became fully operational for the first time.

The Soyuz-2.1b rocket that was used for Sunday’s launch is an upgraded version of the three-stage Soyuz-2 booster. The 151 feet (46.1 meters) tall launch vehicle has a total mass of 672,000 pounds (304,814 kilograms) and is designed to put satellites into a variety of orbits.

The booster is capable of putting up to 18,100 pounds (8,210 kilograms) into low-Earth orbit (LEO), 10,800 pounds (4,899 kilograms) into a Sun-synchronous orbit (SSO), and 7,170 pounds (3,252 kilograms) into a geostationary transfer orbit (GTO). The first launch of this version of the rocket took place from Plesetsk on July 26, 2008, with a classified military payload.

This rocket uses four RD-107A engines at liftoff, which burn for about two minutes. The first stage, 88.9 feet (27.1 meters) long and 9.7 feet (2.95 meters) in diameter, is equipped with a lone 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 of Soyuz has an upgraded RD-0124 engine with a second stage that has improved performance over previous iterations of the design.

For Sunday’s mission, the Soyuz-2.1b rocket was used in a configuration with a Fregat-M third stage. This upper stage measures approximately 4.9 feet (1.5 meters) long and is 11 feet (3.35 meters) in diameter. Its S5.92 engine is designed to burn for about 18 minutes.

Fregat-M is responsible for the orbital insertion of the satellite. However, it can also be used as an escape stage to send probes on interplanetary trajectories. Fregat stages are currently used as the fourth stage for some Soyuz-FG launch vehicles as well.

Sunday’s launch was the 12th flight for Russia, the fourth launch from Plesetsk, and the ninth Soyuz mission of 2016. The country plans to conduct its next launch on June 4 when a Rokot booster is slated to liftoff with the Russian Geo-IK-2 No.12 geodetic satellite. Moreover, at least one more GLONASS-M mission is planned to be performed until year-end.

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