With three days to go, International Launch Services (ILS)—the joint U.S.-Russian company which operates all commercial Proton-M rockets out of Baikonur Cosmodrome, Kazakhstan—stands ready to deliver its first payload of 2014 into geostationary transfer orbit. With liftoff scheduled to occur at 3:09 a.m. local time Saturday (4:09 p.m. EST Friday), the 85th ILS Proton mission will deliver the Türksat 4A communications satellite into orbit on behalf of Türksat Satellite Communications and Cable TV Operations Company, headquartered in Gölbaşı, within Turkey’s Ankara Province. It will be the first time that Türksat has contracted with ILS for launch services.
Built by Mitsubishi Electric (MELCO) at its Kamakura plant in Tokyo, Türksat 4A and 4B will be placed into orbit at 42 degrees East and 50 degrees East longitude respectively. Contracts with ILS to launch the two 8,380-pound (3,800-kg) satellites were signed in April 2011. Speaking at the time, Hiroyuki Inahata, head of MELCO’s space systems division, remarked that the choice of ILS as launch services provider was made “based on their track record of reliability, precision, launch tempo and experience.” With Türksat 4B scheduled to ride another Proton-M later in 2014, efforts are now entering their final stages to prepare Turkey’s communications birds for their missions.
Early last month, during an official visit to Japan by Turkish Prime Minister Recep Tayyip Erdoğan, the Türksat 4A payload was formally handed over by Mitsubishi Electric to Turkish officials. According to ILS, the main team for the mission arrived in Baikonur on 13 January, ahead of the scheduled arrival of Türksat 4A aboard an Antonov carrier aircraft at Yubileiny Airport on 16 January. “It was a wintry landing,” admitted ILS in the first entry of its Türksat 4A mission blog, “but all personnel and their luggage along with equipment landed safely.” Over the following days, the satellite underwent a thorough checkout and loading of propellants for its reaction-control system.
Elsewhere, the launch vehicle components were deep into their own processing regimes, with the Briz-M upper stage fueled on 20 January. Last week, the restartable upper stage was mated with Türksat 4A and encapsulated within its payload fairing, forming the so-called “Ascent Unit” (AU). The combo was then transferred by railcar to Hall 111 at Baikonur to be attached to the Proton-M rocket on Thursday, 6 February.
Final preparations for launch will begin a day or so ahead of liftoff, with the rollout of the three-stage Proton-M to the Site 24 complex. Built by Russia’s Khrunichev Research and State Production Centre, this will be the 393rd mission by a member of the Proton rocket family, which traces its heritage back to the mid-1960s and has one of the most reliable track records of any rocket in the world. However, last year proved troubled when it suffered a dramatic and highly embarrassing launch failure on 2 July, seconds after liftoff. It was the Proton’s first catastrophic malfunction during first-stage flight in over 30 years and prompted several months of corrective actions and cutting managerial and organizational changes. A few weeks later, the Proton returned triumphantly to flight on 29 September, delivering the Astra 2E communications satellite into orbit, and restored its reliability credentials on 25/26 October by launching Sirius FM-6 and on 12 November by launching Raduga-1M-3. Most recently, on 8 December, it flawlessly delivered Inmarsat 5-F1 into orbit.
With Friday’s planned mission to insert Türksat 4A into geostationary transfer orbit, it will be the 85th Proton to fly under the auspices of ILS. The satellite utilizes the Ku-band, Ka-band, and C-band. After launch, Türksat 4A will be placed into a 22,300-mile-high (35,000-km) orbit, at 42 degrees East longitude, from which it will provide communications services and direct television broadcasts across a broad region, from Central Asia, across the Middle East and Africa and Europe, and as far as eastern England. The satellite has a high flexibility of switchability and connectivity among different service areas to its customers.
On launch morning, fueling of the Proton’s three stages with a mixture of nitrogen tetroxide and unsymmetrical dimethyl hydrazine will commence about nine hours before the planned liftoff. The first stage consists of a central oxidizer tank, surrounded by six outboard fuel tanks, each fed by an RD-276 engine, and these will provide the initial impetus to boost Türksat 4A toward space. At T-5 minutes, the Briz-M upper stage will be transferred to internal power and will confirm the health of its systems. Ignition of the six RD-276 engines will commence at T-2 seconds, ramping up to 100 percent of rated performance to produce 2.3 million pounds (1.04 million kg) of thrust at the moment of liftoff.
A little over a minute into the ascent, the Proton will encounter a period of maximum aerodynamic stress (known as “Max Q”) on its flight surfaces, and the separation of the first stage is timed to occur at the two-minute point. The vehicle’s second stage will then pick up the baton, with its four engines generating a combined 540,000 pounds (244,950 kg) of propulsive yield for a little over 3.5 minutes. Soon after second-stage separation, the Payload Fairing (PLF) will be jettisoned and the single-engine third stage will add a further 138,000 pounds (62,600 kg) of thrust for the next four minutes of flight. Shutdown of the third stage should occur about 10 minutes after launch, by which time the vehicle will have been establish onto a suborbital trajectory.
After a 90-second period of coasting, the turn will come for the Briz-M, which has exhibited a mixture of success and failure since its maiden voyage. In August 2012, a premature shutdown of the Briz-M left Indonesia’s Telkom-3 and Russia’s Ekspress-MD2 satellites in useless orbits, and in December 2012 another launch glitch impacted the Yamal-402 satellite. Last March, a Proton-M/Briz-M successfully injected Mexico’s Satmex-8 communications satellite into orbit, and on 29 September another vehicle lofted Astra 2E. Capable of restarting up to eight times in flight, the Briz-M has a battery-powered lifetime of 24 hours and is scheduled to execute five “burns” to insert Türksat 4A into orbit. Assuming an on-time liftoff, the payload should be injected directly into its geostationary orbit about nine hours and 12 minutes into the mission and should communicate with ground stations shortly thereafter.
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