Continued analysis of the payload fairing failure to split and detach from the Orbital Taurus XL launch vehicle has fingered the possible cause.
The heat-treated frangible rail designed to fracture when a pyrotechnic charge is detonated post-launch to shed the rocketís payload-fairing shroud has problems. There are potentially some extrusion problems with the way that material is extruded and the way it is heat treated. It is not uniform along the entire length of the rail.
William Gerstenmaier, associate administrator for NASAís Human Spaceflight and Operations Directorate, says NASA and Orbital investigative teams have traced the problem.
He spoke to the NASA Advisory Councilís human exploration and operations committee in Washington Nov. 15.
ìWe had thought maybe the charge holder had slumped or moved down and that didnít allow the frangible rail to fracture properly,î but in now seems to be a manufacturing problem with the rail.
NASA lost its Orbiting Carbon Observatory in 2009 and its Glory climate-monitor in 2011, both on launches of the Taurus XL, when the vehicleís payload shroud failed to open after separating from the rocket.
Gerstenmaier says both Orbital and NASA investigation teams filed accident investigation reports with NASA in September and December 2011, respectively, both of which failed to determine the root cause of a March 4, 2011, launch failure aboard the Taurus XL that led to the loss of Glory.
Since then, NASA terminated its Taurus XL launch service task order for a re-launch of an identical Orbital Sciences-built OCO spacecraft, though the investigative teams have continued to explore possible root causes of the Glory launch failure. He said the teams have discovered a manufacturing problem ìthat may be more generic than just to the Taurus,î and that while the investigation into this new line of inquiry is preliminary, the findings and mitigation efforts may affect not only the Taurus XL, but other Orbital launch vehicles as well, including the companyís Pegasus, Minotaur and Antares launchers.
Gerstenmaier said the team ìwent out and essentially looked in the scrap bin at some fairings, and we actually investigated some other spacecraft that had some rails.î He says investigators kept digging and, ìwhen they did that, they started discovering some things that didnít look quite right.
Orbital spokesman Barron Beneski says the companyís Antares, Pegasus and Minotaur rockets all fly versions of the frangible joint fairing separation system. These rails are located along the seam between the two halves of Orbitalís clamshell-shaped fairing, as well as at the base of the fairing that connects to the launch vehicle itself.
ìThese come apart to jettison the protective nose cone once the rocket is out of Earthís atmosphere,î Beneski says. ìWe have done a great deal of work on this system since the Taurus XL Glory mission failure to ensure the flight worthiness of the system for upcoming missions, including the Antares test flight.î
