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ILS launches Proton-M rocket with Türksat-4B communications satellite

Proton-M launch of Türksat-4B on Oct. 16, 2015.

Proton-M launch of Türksat-4B on Oct. 16, 2015. Photo Credit: Roscosmos

International Launch Services (ILS) company successfully launched on Friday, Oct. 16, a Turkish communications satellite using a Russian Proton-M booster. Liftoff took place at 4:40 p.m. EDT (20:40 GMT) from the site 200/39 at the Baikonur Cosmodrome in Kazakhstan. The Türksat-4B satellite will be put into a geostationary orbit (GEO) 50° degrees East.

The Proton-M launch vehicle started its ascent by firing the first stage’s six RD-276 engines for the first two minutes of the mission. After the separation of the first stage, the launch vehicle continued its vertical flight until the second stage separated approximately five minutes and 27 seconds after liftoff. The Payload Fairing (PLF) separation occurred 20 seconds later and the Proton’s third stage fired its engines for about four minutes, shutting down nine minutes and 42 seconds into the mission to deliver the Briz-M upper stage and Türksat-4B to a suborbital trajectory.

From this point in the mission, the Briz-M performed 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 will occur after completing five burns of the upper stage, approximately nine hours and 13 minutes after liftoff.

The mission, initially scheduled for Nov. 2014, was postponed to June 2015 and was pushed further after May’s Proton-M failure, putting the launches of this vehicle on hold for three months. The Turksat-4B satellite was delivered to Baikonur on Sept. 2, beginning its final processing flow, putting the satellite through a series of tests before heading into hazardous processing to fuel the spacecraft with propellant. The Briz-M upper stage was delivered from its manufacturer, the Khrunichev State Research and Production Space Center, on Sept. 16. It also entered final processing that included testing activities and fueling of the stage’s high-pressure propulsion system.

The Proton-M rocket was integrated on Sept. 18 and then it underwent a series of integrated tests. The Briz-M upper stage and the satellite were joined and encapsulated in the protective payload fairing, marking the completion of the assembly of the Orbital Unit that was set for transfer to the Launcher Integration Facility. A three-day delay was caused by a crane that suffered an electronics failure, requiring a replacement before the payload stack could be moved onto its transporter.

The rocket was rolled out to the launch pad on Tuesday, Oct. 13. It was then placed in its vertical launch position and teams moved the Service Structure into position to provide access platforms to the Proton for the final preparatory steps ahead of countdown operations. The rocket and Briz-M completed a detailed series of systems checks to ensure all subsystems of the vehicle are ready to support the mission.

Proton-M with Türksat-4B aboard awaiting launch on Oct. 16, 2015.

Proton-M with Türksat-4B aboard awaiting launch on Oct. 16, 2015. Photo Credit: Roscosmos

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 will be put into an elliptical orbit with a high point of 22,236 miles (35,786 kilometers), a low point of 5,767 miles (9,281 kilometers), and an inclination angle of 13.2 degrees to the equator. It 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 191 ft (58.22 m) tall Proton-M rocket employed in Friday’s mission is a Russian heavy-lift launch vehicle used mainly for commercial launches. The rocket utilizes a Briz-M upper stage. 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 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 is the 4th Proton launch conducted by ILS in 2015. It is also the 91st ILS Proton launch overall and the rocket’s third launch since returning to flight after its last crash in May.

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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Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.

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