A Soyuz-2.1b rocket is all set to launch the newest satellite for Russia’s homegrown GLObal NAvigation Satellite System (GLONASS). The spacecraft will blast off at 4:44 a.m. EDT (8:44 GMT) on Sunday, May 29, from the Site 43/4 at the Plesetsk Cosmodrome in northern Russia.
The launch of the mission was initially scheduled for May 21, but was postponed one week. However, the cause of delay wasn’t revealed by the authorities.
The spacecraft, designated GLONASS-M No. 53, was delivered to the launch site on Apr. 22. It was transported to the Plesetsk Cosmodrome aboard a cargo aircraft IL-76.
Final preparations and checkouts to prepare the launch vehicle for its mission will be carried out during an eight-hour countdown that will precede the liftoff. The rocket will be loaded with propellants and the Automated Countdown Sequence will begin, handing over control of the launch to the onboard computers.
After launch, the Soyuz-2.1b rocket will commence a short vertical climb, lasting only a few seconds before starting heading southeast. The vehicle’s four boosters will be jettisoned nearly two minutes into the flight. The mission will last approximately three hours ending with spacecraft separation. After reaching its designated 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), 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 1250 W, 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.
GLONASS-M spacecraft are 3-axis stabilized, nadir pointing with dual solar arrays. The payload consists of L-Band navigation signals in 25 channels separated by 0.5625 MHz intervals in 2 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 system, operated by the Russian Aerospace Defence Forces, 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 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.
The Soyuz-2.1b rocket that will be 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 lbs. (304,814 kg) and 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 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 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 will be 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 lift off the Russian Geo-IK-2 No.12 geodetic satellite.