Proton-M rocket to launch Turkish communications satellite on Friday
A Russian Proton-M rocket is being readied for a Friday, Oct. 16 launch, when it will loft the Turkish Türksat-4B communications satellite into orbit. Liftoff is currently scheduled to take place at 4:40 p.m. EDT (20:40 GMT) from the site 200/39 at the Baikonur Cosmodrome in Kazakhstan. The satellite will be put into a geostationary orbit (GEO) 50° degrees East. International Launch Services (ILS) will manage the mission.
The first three stages of the Proton-M will use a standard ascent profile to place the orbital unit (Briz-M upper stage and the satellite) into a suborbital trajectory. From this point in the mission, the Briz-M will perform the planned mission maneuvers to advance the orbital unit. First, to a circular parking orbit, then to an intermediate orbit, followed by a transfer orbit, and lastly to GEO. Separation of the satellite is scheduled to occur approximately nine hours and 13 minutes after liftoff.
Türksat-4B is one of the two satellites built by Mitsubishi Electric Corporation (MELCO) for Türksat Satellite Communication, Cable TV and Operation Inc. (Türksat AS), the country’s national satellite operator. Along with Türksat-4A, launched on Feb. 14, 2014, the satellites will enable the Turkish company to offer telecommunication and direct TV broadcasting services throughout Turkey, as well as in Europe, Central Asia, the Middle East, and Africa.
The satellite will expand the space capacity of Turkey and provide enhanced performance to its coverage areas. It will provide high flexibility of switchability and connectivity among different service areas to its customers.
Weighing nearly five metric tons and spanning about 83 ft (25.3 m) when fully deployed in orbit, Türksat-4B will accommodate 43 communication channels. It will provide data and Internet services to companies and domestic users on Ka band in addition to TV broadcasting.
The spacecraft hosts a 5.25-ft (1.6 m) Ku-Band array antenna on its Earth-facing panel plus two reflector antennas 8.2 ft (2.5 m) and 7.2 ft (2.2 m) diameter, respectively. It uses a bipropellant propulsion system featuring an apogee kick motor plus 12 thrusters for attitude control and station-keeping maneuvers.
Türksat-4B is equipped with two high-efficiency silicon, multi-junction three-panel GaAs solar arrays that deliver power to dedicated avionics that distribute electrical power to all satellite systems via a regulated 100-Volt main bus.
The satellite is expected to be operational for 15 years and has a propellant supply that could even extend the mission lifespan to 20 years.
Türksat-4B is based on MELCO’s DS2000 bus, a modular platform with the flexibility to handle a broad range of payload applications. The bus is capable of providing an output of up to 15 kW, satisfying the power requirements for powerful and multiple communications transponders. Its flexible design matches various applications including hybrid communications payloads.
Mitsubishi states that this platform has a highly reliable design, and production is based upon rich experience derived from participation in more than 280 satellite projects worldwide. MELCO has participated in more than 440 domestic and international satellites as prime contractor and major subcontractor.
The DS2000 platform was developed based on a design originally made for the DRTS and ETS-VIII platforms through development by the Japan Aerospace Exploration Agency (JAXA). After winning an international bid competition for the MTSAT-2 – a Japanese commercial satellite launched in 2006 – the company incorporated evolutionary changes to match the requirements for standard commercial communications satellites and introduced the DS2000.
The production of Türksat-4B at the Mitsubishi Electric Facility in Kamakura, Japan, was completed in June 2014. The launch of this satellite was initially planned for June 30, 2015.
The 191 ft (58.22 m) tall Proton-M rocket that will be employed in Friday’s mission is a Russian heavy-lift launch vehicle used mainly for commercial launches. The rocket, built by the Khrunichev State Research and Production Space Center, will utilize a Briz-M upper stage for the Türksat-4B mission. This stage is powered by one pump-fed gimbaled main engine that develops a thrust of 20 kN (4,500 lbf). It is composed of a central core and an auxiliary propellant tank, which is jettisoned in flight following depletion.
The Briz-M control system includes an onboard computer, a three-axis gyro stabilized platform, and a navigation system. The quantity of propellant carried is dependent on specific mission requirements and is varied to maximize mission performance.
The Proton booster is 13.5 ft (4.15 m) in diameter along its second and third stages, with a first stage diameter of 24.3 ft (7.4 m). The first stage consists of a central tank containing the oxidizer surrounded by six outboard fuel tanks. Each fuel tank also carries one of the six RD-276 engines that provide first stage power.
The second stage is powered by three RD-0210 engines plus one RD-0211 engine. The third stage is powered by one RD-0213 engine and a four-nozzle vernier engine. Guidance, navigation, and control of the Proton-M during operation of the first three stages is carried out by a triple redundant closed-loop digital avionics system mounted in the Proton’s third stage. The first Proton-M launch occurred on April 7, 2001.
Friday’s liftoff will be the 4th Proton launch conducted by ILS in 2015. It will also be the 91st ILS Proton launch overall.
The previous Proton-M launch was performed on Aug. 28, 2015, when the rocket sent the British Inmarsat 5-F3 communications satellite into orbit. Next launch of this booster is planned for November this year, with the Russian Garpun communications spacecraft on board.
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