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A Weak Briz: Engine Shortfall Likely Caused Satellite Losses

The Proton-M thunders into the darkened Baikonur sky on Monday evening, beginning what should have been a nine-hour journey to geosynchronous orbit for Telkom-3 and Ekspress-MD2. Despite the satisfactory performance of the rocket itself, the Briz-M upper stage apparently malfunctioned and has left both satellites stranded in useless orbits. Photo Credit: Roscosmos

A Russian State Commission has convened to investigate the cause of Monday’s Proton-M launch failure, which stranded a pair of communications satellites in useless orbits. Preliminary details suggest that a premature shutdown of the Briz-M upper stage – which has suffered its fair share of mishaps in recent years – sounded the death knell for Indonesia’s Telkom-3 and Russia’s Ekspress-MD2. According to data released yesterday by the US Strategic Command (USSTRATCOM), the satellites, the Briz-M and their associated hardware, presently occupy a looping elliptical orbit with a perigee of around 400 miles and an apogee of 3,500 miles. This raises the likelihood that they will re-enter the atmosphere to destruction in the next few weeks.

The road to launch was long and troubled for the satellites and the Briz-M. Originally scheduled to fly in May, the mission slipped repeatedly into June, July and eventually into early August. Three weeks ago, officials acknowledged that “problems” with the Briz-M were responsible for the delays, but last Thursday the State Commission nevertheless approved the 174-foot-tall Proton-M booster for rollout to Site 81 at Baikonur Cosmodrome in Kazakhstan. On Monday afternoon, loading of nitrogen tetroxide and unsymmetrical dimethyl hydrazine propellants commenced, ahead of the scheduled launch at 11:31 pm Moscow Time (1:31 am local time on Tuesday 7th). Precisely on time, the Proton-M roared into the night sky in what seemed to be a picture-perfect ascent.

With a heritage that extends back to 1965 and encompasses almost 400 missions, the Proton is among the world’s most reliable heavy-lift rockets and is today used both by the Russian government and by International Launch Services (ILS). The Proton-M, built by the Khrunichev Research and State Production Centre, boasts a number of performance enhancements which reduce its structural mass, increase its overall thrust and more fully utilise its propellant reserves. Its first stage consists of a central oxidizer tank, surrounded by six outboard fuel tanks, fed by six RD-276 engines, with a thrust of 2.3 million pounds. The second stage is powered by four engines and yields 540,000 pounds, whilst the single-engine third stage produces 138,000 pounds. In the case of Monday night’s launch, it would appear that the Proton-M functioned normally, but the Briz-M upper stage – whose single engine is capable of restarting as many as eight times in flight – malfunctioned shortly after it began the complex process of transferring the payload to its 22,600-mile geosynchronous orbit. Two of the scheduled five engine firings were successful, but the third fell significantly short. Instead of burning for 18 minutes, the Briz-M failed to achieve its proper thrust, spluttered and died after barely seven seconds.

The Proton-M vehicle is rolled out horizontally to its launch pad. Photo Credit: Roscosmos

This was very grim news for Telkom-3 and Ekspress-MD2, both of which now linger in an off-nominal intermediate orbit. Professional and amateur skywatchers have reported up to four objects flying in tandem, suggesting that the Briz-M separated the two satellites and its own Auxiliary Propellant Tank (APT) after the engine failure. Unlike many communications satellites, which employ integral kick motors to accomplish final positioning in geosynchronous orbit, Telkom and Ekspress were meant to be injected directly into their final operational slots by the Briz-M. The reason: the only way for two large payloads to ride a single Proton-M was to launch them with the bare minimum of propellant.

The greatest irony, perhaps, is that Telkom-3 and Ekspress-MD2 were not manifested to fly together at all, until comparatively recently. In fact, the former was assigned to fly with the Yamal-300K satellite, following a 74.5-degree launch azimuth to enter a 48-degree initial orbit. However, the loss of Japan’s JCSat-11 in September 2007 – whose Proton-M suffered a stage separation failure and deposited debris within 50 miles of the city of Dzhazkazgan – prompted the Kazakh government to prohibit launches into orbital inclinations of less than the standard 51 degrees. This led to a juggling of payload assignments.

Telkom-3 was the first Indonesian satellite to be purchased from a Russian company (in this case, ISS-Reshetnev), although its communications payload was assembled by Thales Alenia Space. Its owners, the Telkom Group, reportedly invested $200 million into the project, whose primary purpose is to cater for increased business demands, an enhanced ICT infrastructure in Indonesia and to support government and military functions. Designed for an operational lifespan of 15 years, the satellite was to replace the Lockheed Martin-built Telkom-2, although Indonesian officials have been quick to quash fears that the loss will impair their communications capabilities. “They can still handle operations well,” said Communications and Information Ministry spokesman Gatot S. Dewabroto, although he stressed that Telkom now needs a “Plan B” in the wake of the accident.

Meanwhile, the loss of Ekspress-MD2 comes barely a year after another Briz-M failure doomed its predecessor, Ekspress-AM4, in a similar manner last August. As with Monday’s launch, the flight began normally: the first-stage engines ignited 1.75 seconds before liftoff and were throttled up to full power, before the shackles were broken at T-zero and the vehicle commenced its climb for the heavens. Separation of the first stage and ignition of the second stage followed a little over two minutes into the ascent and the third stage picked up the thrust at five and a half minutes after launch. Then came the turn of the Briz-M. To insert Ekspress-AM4 into geosynchronous orbit, it was programmed to execute five engine burns…but completed just three of them. At some point, either at the start of the fourth burn or midway through it, the controllers lost contact with the Briz-M. The investigation which followed blamed the failure on attitude-control problems, weak telemetry and difficulties with the gyroscopic platform. Ekspress-AM4 re-entered the atmosphere and was destroyed in late March 2012.

Telkom-3 is hoisted into position above the Briz-M upper stage, during final pre-launch preparations. Photo Credit: Roscosmos

Monday’s failure is a crushing disappointment, for the newest Ekspress was to be positioned over the Russian Far East. Built by Khrunichev and Thales Alenia Space, the satellite was targeted to spend ten years in orbit, providing communications and broadcasting services across the vast expanse of northern Asia. Since the failure, the Russian media has put a 5-billion-rouble price tag on the loss of Telkom-3 and Ekspress-MD2 and the investigative commission is already closing in on the most likely cause of the failure: an insufficient build-up of thrust in the Briz-M, prompting its premature shutdown.

Two failures of the upper stage, within a year, are unwelcome additions to Briz-M’s tally. In March 2008, it suffered a ruptured gas conduit and failed during its second engine firing. This doomed its primary payload, SES Americom’s ASC-14 communications satellite. More recently, in February 2011, the Briz-M refused to restart in orbit and Russia’s Geo-IK-2 geodetic satellite was lost. On a third occasion, in February 2006, the Proton-M itself failed and its Briz-M was left loitering helplessly in low-Earth orbit, with a full tank of propellant. It exploded over Western Australia in February 2007, producing more than a thousand pieces of space debris.

Watching the latest Briz-M failure with dismay is Reston, Virginia-based International Launch Services (ILS), which provides commercial opportunities on the Proton-M. As the Russian State Commission digs into the cause of Monday’s incident and takes steps to restore the booster and the Briz-M to flight status, ILS’s own Failure Review Oversight Board will monitor the proceedings. In so doing, they will fulfil a key requirement of US and Russian government export control regulations. Yet with an impressive success rate, one thing can be certain: the Proton-M may be temporarily out of action, but definitely not out of the game.

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