NASA Unable To Determine Root Cause of Last Year's Orb-3 Failure

One year and a day after Orbital Sciences Corporation’s Antares rocket exploded shortly after liftoff, NASA released an executive summary of its independent review of the event.  The rocket was launching a Cygnus cargo ship full of supplies for the International Station Station (ISS) under a NASA-Orbital contract.   NASA said it could not determine the root cause, but identified three possibilities. Orbital, which merged with ATK earlier this year and is now Orbital ATK, has not publicly released its own report. 

The launch of the company’s third operational commercial cargo mission for NASA, Orb-3, took place from Wallops Island, VA on October 28, 2014.  Fifteen seconds after launch, it exploded.   As a commercial launch, it was governed by the FAA’s regulations, which puts accident investigations in the hands of the company itself, not the customer — in this case NASA. NASA decided on its own to create an Independent Review Team (IRT). 

Orbital’s President and CEO, David Thompson, said just one day after the failure that one of the two NK-33/AJ-26 engines most likely was at fault.  The NK-33 engines were built in Russia more than four decades ago and refurbished in the United States by Aerojet (now Aerojet Rocketdyne) and redesignated AJ-26.  In subsequent months, Orbital and Aerojet reportedly agreed that the problem stemmed from a bad bearing, but disagreed on whether Aerojet failed to detect a faulty bearing or if the bearing was damaged by foreign object debris (FOD) ingested during the launch.

On September 24, 2015, Aerojet Rocketdyne submitted a filing to the Securities and Exchange Commission to say it was paying Orbital ATK $50 million to terminate the contract for the AJ-26 engines and settle all claims the companies “may have had against one another.”   Orbital ATK will return title to the remaining 10 AJ-26 engines to be delivered under that contract.

In the executive summary of NASA’s IRT report, NASA added a third possibility — inadequate design robustness of the hydraulic balance assembly and turbine-end bearing.  Sufficient testing would have revealed this problem, the IRT said, but was not performed.

The IRT could not determine which of the three possible root causes — a mechanically faulty bearing, FOD, or poor design — was at fault.

Orbital is refitting Antares with different Russian rocket engines (RD-181s), so the precise cause may not be all that important for returning Antares to flight, but NASA’s interest is in ensuring that the company is taking the appropriate steps to ensure no similar failure occurs with the new engines.   The IRT report says that NASA provided “several” technical recommendations, but was not making them public because of “potential proprietary and export control restrictions.”

In an investors conference call earlier this week, Thompson said that repairs to the facilities at Wallops damaged by the launch failure are complete and a “hot fire” test of an Antares outfitted with the new engines is planned for January 2016.   He said the company is aiming for “early May” for the first launch of the new version of Antares. 

In the meantime, two of the company’s Cygnus cargo spacecraft will be launched on United Launch Alliance Atlas V rockets instead.  That will allow Orbital ATK to meet its contractual requirements to send 20 tons of cargo to the ISS by the end of 2016.  Cygnus has also been upgraded so it can carry more cargo per launch than the prior version.

The first Atlas V/Cygnus launch is scheduled from Cape Canaveral, FL on December 3, 2015.  The second will take place on March 10, 2016, Thompson said, followed by the return to flight of Antares from Wallops in May and a second Antares/Cygnus launch in late September/early October.   Thompson said those launches would “substantially” complete the company’s original Commercial Resupply Services (CRS) contract.   It has been awarded three additional cargo flights under an extension of the CRS contract.  They will take place in 2017 and early 2018.  Orbital ATK also is one of the competitors in the second round of CRS contracts.  Winners of the CRS-2 competition are expected to be announced a week from today (November 5).

SpaceX is the other company currently under contract to NASA to send cargo to the ISS.   It, too, suffered a launch failure recently.  Its Falcon 9 rocket exploded 139 seconds after launch on June 28, 2015 destroying a Dragon capsule also filled with supplies for ISS.   An exact date for returning Falcon 9 to flight has not been announced, but company officials said last week that it will be in 6-8 weeks.  That launch will be of a set of Orbcomm-2 commercial communications satellites.  The next launch of cargo to the ISS on a Dragon spacecraft has not been announced.