Investigators probing last week’s catastrophic failure of an Antares commercial rocket moments after liftoff, are pointing the finger at the rockets Soviet-era built engines as the probable cause of the huge explosion that destroyed the booster and its NASA payload in a raging fireball after liftoff from NASA’s Wallops Flight Facility, VA, according to a Orbital Sciences officials.
The Orbital Sciences privately developed Antares rocket was doomed by a sudden mid-air explosion some 15 seconds after liftoff from NASA’s Wallops Flight Facility, VA, at 6:22 p.m. EDT on Tuesday, October 28.
Antares first stage is powered by a pair of refurbished Aerojet Rocketdyne AJ26 engines originally manufactured some 40 years ago in the then Soviet Union and originally designated as the NK-33.
Photos above and below showing the AJ26 engines with their original NK-33 decal, during prelaunch processing and mating to the first stage inside Orbital’s Horizontal Integration Facility (HIF) at NASA Wallops.
Rocket developer Orbital Sciences Corp. said today that the launch mishap was probably due to “a failure in one of the two Aerojet Rocketdyne AJ26 stage one main engines.”
Engineers assisting Orbital’s Accident Investigation Board (AIB) say that failure in the AJ26 turbopump is the likely cause.
“While the work of the AIB continues, preliminary evidence and analysis conducted to date points to a probable turbopump-related failure in one of the two Aerojet Rocketdyne AJ26 stage one main engines,” Orbital said in a statement. “As a result, the use of these engines for the Antares vehicle likely will be discontinued,” said Orbital.
The Oct. 28 launch disaster was just the latest in a string of serious problems with the AJ-26/NK-33 engines. Earlier this year an AJ26 engine failed and exploded during acceptance testing on a test stand on May 22, 2014 at NASA’s Stennis Space Center in Mississippi.
Besides completing destroying the AJ26 engine, the explosion during engine testing also severely damaged the Stennis test stand. It has taken months of hard work to rebuild and restore the test stand and place it back into service.
An extensive engine analysis and recheck by Aerojet Rocketdyne and Orbital Sciences engineers was conducted to clear this new pair of engines for flight.
AJ26 engine failure was immediately suspected, though by no means certain, based on an inspection of numerous photos and videos from myself and many others that clearly showed a violent explosion emanating from the base of the two stage rocket.
The AIB is chaired by David Steffy, Chief Engineer of Orbital’s Advanced Programs Group.
The remainder of the first stage and Antares entire upper stage was clearly intact at the moment of the explosion in all the imagery.
Antares was carrying the unmanned Cygnus cargo freighter on a mission dubbed Orb-3 to resupply the six person crew living aboard the International Space Station (ISS) with science experiments and needed equipment.
The AIB is making rapid progress in assessing the accidents cause based on an analysis of the rockets telemetry as well as the substantial amounts of debris collected from the rocket and the Cygnus cargo freighter at the Wallops launch site.
A preliminary review of telemetry and video data has been conducted and substantial debris from the Antares rocket and its Cygnus payload has been collected and examined.
The 14 story Antares rocket is a two stage vehicle. The liquid fueled first stage is filled with about 550,000 pounds (250,000 kg) of Liquid Oxygen and Refined Petroleum (LOX/RP) and powered by a pair of AJ26 engines that generate a combined 734,000 pounds (3,265kN) of sea level thrust.
The doomed mission was bound for the International Space Station (ISS) on a flight to bring up some 5000 pounds of (2200 kg) of science experiments, research instruments, crew provisions, spare parts, spacewalk and computer equipment and gear on a critical resupply mission in the Cygnus resupply ship bound for the International Space Station (ISS).
The Orbital-3, or Orb-3, mission was to be the third of eight cargo resupply missions to the ISS through 2016 under the NASA Commercial Resupply Services (CRS) contract award valued at $1.9 Billion.
Orbital Sciences is under contract to deliver 20,000 kilograms of research experiments, crew provisions, spare parts and hardware for the eight ISS flights.