An obscure mechanism which caused three Space Systems/Loral-manufactured satellites, Telstar 14, Telstar 14R and Intelsat 19 to have solar array failures during their launches/deployments has finally been discovered. In an interview conducted in the space newspaper Space News (Peter B de Selding, 7 January 2013), John Celli, President of the US spacecraft manufacturer Space Systems/Loral, revealed that the eight-year-old mystery into why three satellites had major solar array failures had been solved by an independent investigation team. It found that it was inadvertent solar array pressurisation and exposive decompression that was the underlying cause.
Specifically, during the launch phase, the satellites’ solar arrays had actually become pressurised relative to their ambient environment as the launch vehicle rose in altititude. This eventually led to an explosive event which damaged the array’s deployment mechanism and structure. It was a manufacturing defect that was found to be the root cause including overly pinching the ends of the panels which would not let gasses vent from the honeycomb structure, and having insufficent bonding of the layers of the panel making it more susceptible to explosive depressurisation.
The result was that in January 2004, Telstar 14 (Estrela Do Sul) had an explosive event during its Zenit 3-SL (Sea Launch) flight which caused the resulting deployment failure of its North solar array. According to the Flightglobal SpaceTrak database this led to a $205 million insurance loss. Although the exact cause remained a mystery,evidence that an explosive event had been detected by onboard sound sensors hinted that the launch vehicle was in some way at fault.
The second failure, this time to the Telstar 14R (Estrela Do Sul 2) spacecraft again involved a deployament fault to the North Solar array deployment failure shortly launch in May 2011 on a Proton M Breeze M launch vehicle. The resulting power loss and need for extra fuel use due to the imbalanced configuration resulted in an insurance loss of $132.7 million. At the time, a causal link with the first failure was ruled out as the cause was found by a board of investigation to have been a small nylon clip coming loose allowing a cable to snag on a piece of meta lbeing used to hold the North solar array in folded position against the satellite’s body during launch. It was only later that it was realised that an explosive event during the launch had caused this snagging event.
Intelsat 19′s solar array deployment issues finally led to the mystery cause being found. Courtesy: Space Systems/Loral
It was the third and final solar array deploymenet fault to Intelsat 19 in June 2012 that finally ended the mystery, After a very difficult solar array deployment following the Intelsat 19 satellite’s launch, it was discovered that the spacecraft had suffered a power loss. This later resulted in an insurance loss of $84 million. Again an intra-fairing “pressure event” was detected during the flight of Zenit 3-SL (Sea Launch) rocket. The initial investigation soon realised that it was a launch event that was the cause of the failure. A later investigation by an Independent Oversight Board into this failure and to similar events to Telstar 14 and Telstar 14R finally discovered that the root cause was the manufacturing/inadvertent pressurisation fault.
While Space Systems/Loral gained plaudits for being gracious in taking full responsibilty for the faults, probably most relieved was the now exonorated Sea Launch firm which had to contend with years of suspicion following the initial Telstar 14 deployment failure.