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The Zenit rocket explodes on the launch pad in the Pacific Ocean

Published: 2007 Jan. 30; updated: Jan. 31, Feb. 1, Feb. 2, Feb. 3, Feb. 4

The Zenit-3SL (No. SL24) rocket exploded at liftoff from the Sea Launch platform stationed in the Pacific Ocean Tuesday. According to witnesses, the RD-171 engine of the first stage had just ignited, followed by a tilt of the rocket and by the immediate fireball, which completely obscured the vehicle. The live webcast of the launch was cut off shortly thereafter.

The mission, which was scheduled to lift off on January 30, 2007, at 23:22 GMT, (18:22 EST, 15:22 PST), was to deliver the NSS-8 communications satellite for New Skies company. The spacecraft was destroyed in the mishap.

The Sea Launch company announced that the rocket "experienced an anomaly," but nobody was injured in the accident. "Sea Launch will establish a Failure Review Oversight Board to determine the root cause of this anomaly," the company said in a press release.

Amazingly, the Russian mission control, which routinely supports Sea Launch operations, apparently had not been receiving accurate information on the status of the mission, since its representative told the Interfax news agency that it lost telemetry from the satellite some 40 seconds after liftoff, but still hoped to regain communications! Interfax then dutifully disseminated the information.

The ill-fated mission was delayed by weather and technical glitches from Jan. 25, Jan. 28 and Jan. 29, 2007. At the time of the accident, the Sea Launch had a backlog of three launches in 2007, including Thuraya D3, Spaceway F3 and DIRECTV 11, all built by Boeing.

Several hours after the launch, Russian industry sources reported that the floating platform survived the accident and sustained minimal damage. However onboard web cameras, which remained operational after the accident, showed smoke and sings of fire on the platform. As of Wednesday, January 31, questions still remained, whether the self-propelled platform would be capable of returning to its home port in Long Beach, California. Even then, some observers expressed concern that the damage to the Odyssey platform could be serious enough to require sending it to one of dry docks half a world away for repairs, something partners who fund the Sea Launch venture might not be able to afford.

In 1990, the explosion of the Zenit-2 rocket destroyed its launch pad in Baikonur.

The investigation and recovery

Based on the preliminary review of the launch video, it seemed that the launch vehicle had began sliding down the exhaust duct of the launch pad, moments before a scheduled liftoff. However, a representative of KB Yuzhnoe design bureau told the reporter from web site that the failure of the launch equipment would likely be ruled out as the cause of the failure and the rocket itself was a culprit. According to one report posted on the Novosti Kosmonavtiki web forum, telemetry from the engine of the first stage was lost 3.9 seconds after a scheduled liftoff. At the time, the spin rate of the main turbo pump was nominal, however, some anomalies were detected after a very preliminary review of the data.

In addition, according to uncofirmed reports from sources at KB Yuzhnoe, the prime manufacturer of Zenit, the main engine of the rocket developed around 80 percent of its nominal thrust and then shut down four seconds after liftoff. The rocket, reportedly lifted less than half a meter before collapsing into the sea, possibly falling through a flame duct of the launch platform.

On February 1, 2007, a representative of KB Yuzhnoe design bureau confirmed earlier reports that the problem with the engine of the first stage and its propellant, (likely liquid oxygen) supply system caused the accident. There were still conflicting reports about the condition of the Sea Launch platform, even though it seemed that the facility did escape major damage. To most observers, the explosion of the rocket was primarily contained below the launch deck of the platform, perhaps allowing the force of the blast to dissipate in the open area below the platform.

On the same day, the Sea Launch released an official statement, which said that the company was "in the process of securing the Odyssey Launch Platform and taking initial measures to determine the root cause and implement necessary corrective actions" According to Sea Launch, "a preliminary assessment of the Odyssey Launch Platform indicates that, while it has sustained limited damage, the integrity and functionality of essential marine, communications and crew support systems remains intact. The vessel is operating on its own power and is currently manned by the full marine crew. This team is performing a comprehensive assessment of all aspects of the vessel, including its structural integrity and sea-worthiness, in anticipation of identifying and planning the next steps."

In the meantime, Ivan Safronov, a well-informed correspondent with the Kommersant newspaper quoted sources at Sea Launch as saying that the rocket lifted only four centimeters from the pad and then tilted and collapsed on the launch platform. The explosion sheered a flame deflector, which then sunk, and also damaged one of the platform's main pillars, which started leaking. However according to a later report, the hole in the pillar was above the water line, and, therefore, did not pose a threat to the platform.

On February 2, 2007, Russian media reported that the Sea Launch platform could still move under its own power, despite some damage to the launch pad and to a number of structures on the main deck. Singapore was named as a possible destination for the platform, where a dry dock could accommodate the vessel for necessary repairs. On the same day, the Los Angeles Times quoted Paula Korn, the Sea Launch representative, as saying: "It’s amazing, there was some damage to the pad, but the bridge is fine and the light bulbs in the hangar are still on and working." In interview to Press Telegram, Korn said that a crew of 25 was working on the Sea Launch platform, assessing the damage.

Later in a day, a posting on the Novosti Kosmonavtiki web forum said that, based on the video surveying the Odyssey platform after the accident, most hardware on the top deck, including the main hangar, remained visibly untouched, no tilt of the platform was noticeable, however the umbilical boom used to connect the rocket to the launch equipment was apparently missing.

Post-accident photos

On February 3, 2007, first images of the top deck of the Odyssey platform and its underside, as they looked after the accident, surfaced on the Internet. They revealed a missing flame deflector below the launch platform, sliding doors of the hangar blown off their tracks and moderate amount of burn marks around the pad. However the rest of the structures looked intact, including fragile lights and radar antenna on the top deck. A critical umbilical mast, which enables the interfaces between the rocket and launch equipment was found in retracted position and visibly intact, even though with burn marks.

It was also obvious from the photos, that the interface plate connected to the side of the Zenit at launch had not jettisoned at liftoff, which was an evidence that the rocket's upward movement during the accident did not exceed 85 milimeters.

According to the latest unconfirmed reports from Russia, a preliminary analysis of the failure showed that the rocket lifted around 10-15 centimeters above the launch pad, after which pressurization of the oxidizer tank was lost, apparently leading to the main engine shutdown.

In the meantime, the word came that the Odyssey platform and the support vessel were on the way back to their home port of Long Beach, California. Within 24 hours, Sea Launch finally released a first "official" post-accident photo showing slightly blackened platform steaming back to home port with the Sea Launch Commander command and control ship cruising along.

On February 8, 2007, Sea Launch finally confirmed that the command ship and the platform return to the home port. According to the company's press-release, "In the process of verifying her seaworthiness, the marine crew has confirmed that the Odyssey’s main structures are in good condition and marine systems are operational. Like the Sea Launch Commander, the Odyssey is currently in transit to home port under her own power and at normal speed, and is expected to make a timely return."

"Sea Launch is developing the necessary plans and procedures to fully assess the damage to the Launch Platform and implement the necessary repairs required for re-certification to ensure a safe, thorough and efficient return to reliable service. While the final assessment will be completed when the launch platform arrives at home port, the most notable findings at this time are the loss of the flame deflector, located below the launch pad, and the position of the aft doors of the hangar, which are off of their supports. This hangar houses and protects the transporter-erector support structure during launch operations. Preliminary assessments indicate that other launch support equipment is in good condition."

Initial failure scenarios

Long before formal investigation into the Sea Launch accident was to be completed, a number of possible scenarios emerged in the press, as often colored by mutual finger-pointing of international contractors involved in the Sea Launch venture:

  • The hypothesis about the disintegration of the oxidizer line, as a result of a production defect at KB Yuzhnoe in Dnepropetrovsk, Ukraine, was quoted by the Kommersant newspaper on February 13, 2007, and perhaps, originated from Russian sources, since it would place the blame for the accident at the feet of Ukrainians. Not surprisingly, KB Yuzhnoe immediately denied that conclusion and said that the investigative commission still had up to 50 possible scenarios on the table at the time.
  • The failure of the oxidizer turbopump in the RD-171 engine, which would explain the loss of pressure or a total loss of oxidizer supply into the engine. There was also rumor that telemetry data, actually showed a rise in pressure at the entrance into the oxidizer pump. This scenario could blame Moscow-based NPO Energomash, which builds RD-171 engine.

Impact on the Sea Launch customer

The ill-fated Zenit-3SL rocket was carrying the NSS-8 satellite for the SES New Skies company, headquartered in Hague, Netherlands, and had regional offices in Hong Kong, New Delhi, São Paulo, Singapore, Sydney and Washington, D.C. As a part of SES company (Euronext Paris and Luxembourg Stock Exchange: SESG) it offered satellite communication services to a range of customers including telecommunications providers, broadcasters, corporations and governments around the world.

According to New Skies, NSS-8 was to be a high-powered, state-of-the-art, Ku- and C-band communications satellite located at 57º East over the Indian Ocean. It was to provide coverage of Europe, Africa, the Middle East, the Indian sub-continent and Asia, with the intention to replace NSS-703 and bring expanded power and coverage at this optimum and well-established orbital location.

The launch failure of NSS-8 meant that NSS-703 would stay at 57º East in order to continue to serve existing customers until at least 2009.

SES NEW SKIES has already begun construction of NSS-9, which is scheduled to be launched in early 2009 to the Pacific Ocean Region, freeing up NSS-5 which will be relocated to 57º East to replace NSS-703.

Sea Launch accident investigation concludes

Published: 2007 March 14

A foreign object doomed the launch of the Zenit-3SL rocket, which exploded on its ocean-based platform on Jan. 30, 2007, a Ukrainian official said. The investigation commission, which completed its work on March 9, 2007, concluded that a foreign metallic object in the oxidizer turbopump of the Zenit's 1st stage engine was determined to be a culprit. Yuri Moshnenko, a representative of Ukraine-based KB Yuzhnoe, which built the rocket, was quoted by UNIAN news agency, as saying that the size of the object was not determined, however it could be as small as several millimeters and could enter the pump with the oxidizer stream.

The commission put forward recommendations for preventing a similar incident in the future and developed a schedule for the return to flight. According to Moshnenko, the next launch attempt from the Sea Launch platform could take place in the summer or fall 2007.

Moshnenko said that the commission saw no problems with the performance of the RD-171engine itself.

It took Sea Launch until April 3, 2007, to finally release a statement saying that it made a "significant progress in repairs to the Odyssey Launch Platform." As was reported weeks before, the press-release confirmed that the investigative commission recently concluded that an anomaly within the first stage engine caused early termination of thrust, resulting in the loss of the mission.

According to Sea Launch, "Failure Review Oversight Board (FROB) is meeting this week in Dnepropetrovsk, Ukraine, with representatives of the interagency commission and Sea Launch partner companies, to evaluate the commission's findings regarding the root cause of the anomaly and recommended corrective actions. The FROB is comprised of Sea Launch technical leadership and U.S. aerospace industry experts as well as customer representatives. Upon completion of the meetings, the FROB Chairman will determine whether to close the FROB and begin implementation of the recommended corrective actions or to keep the FROB open for further investigation and evaluation."

"Concurrently, the Sea Launch team has completed its damage assessment phase of the Odyssey Launch Platform, including repair and recertification requirements and scheduling of repair activities. The team is now engaged in a fully integrated recovery process to restore all damaged systems back to their original operating capability. The most significant of these efforts will be the construction and installation of a new gas deflector located beneath the launch pad, replacement of heat-affected cable and wiring, replacement of the launch support umbilical interface to the launch vehicle, and painting of the external surfaces."

"The one-of-a-kind gas deflector - a 250-metric ton steel structure that directs the engine exhaust away from the platform and controls the acoustic environment - is being built in St. Petersburg, Russia, by the original subcontractor. The Design Bureau of Transport Machinery (KBTM), Sea Launch's Russian contractor for much of the launch support equipment, is managing this effort. Upon completion of the fabrication of the deflector, KBTM will ship the structure to Sea Launch home port in California for installation on the launch platform. Additional heavy industrial repair work and painting will be performed at a shipyard on the West Coast of North America."

Based on current progress, Sea Launch anticipates the FROB activity will be completed by June 2007, followed by implementation of the necessary corrective actions leading to return to flight. The Launch Platform repair and recertification operations are expected to be completed in September 2007."

The statement promised the return to flight in October 2007.

Return to flight

To resume flights, Sea Launch initiated number of repairs to the launch platform. It included heat-affected cable and wiring, the launch support umbilical interface to the launch vehicle, and painting of the vessel’s external surfaces, according to Sea Launch. The aft doors of the hangar required re-installation on their supports. The hangar houses and protects the transporter-erector support structure during launch operations.

Some of the work on the launch platform had been performed at Sea Launch home port. Additional heavy industrial repairs and painting were performed at a shipyard in British Columbia over several weeks in June and July. The platform arrived there in June 2007.

According to Sea Launch marine tests of the repaired pltaform were planned for the end of the summer. Final repair and recertification operations were expected to be completed in September 2007 at home port.

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The Zenit rocket moments before explosion. A small patch of black smoke, a possible indication of a problem with the engine's turbopump, can be seen on the right of the vehicle, which apparently already collapsing below the launch deck. Credit: Sea Launch

The Zenit rocket explodes on the launch pad Tuesday, Jan. 30, 2007. Credit: Sea Launch

Areas of confirmed damage onboard Odyssey in the aftermath of the launch failure on Jan. 30, 2007 shown on the pre-launch file photo. Click to enlarge. Credit: Sea Launch

The Odyssey platfrom returns home on February 3, 2007, after an ill-fated launch of the Zenit-3SL rocket. Click to enlarge. Credit: Sea Launch

The RD-170 engine powered the first stage of the Energia rocket and its slight variation, designated RD-171, powered the Zenit family of rockets. It was a likely culprit in the failure of the Zenit-3SL rocket in January 2007. Click to enlarge: 300 by 400 pixels / 56K Copyright © 2005 Anatoly Zak

The NSS-8 satellite was lost in the Sea Launch accident in January 2007. Credit: Sea Launch