Failure of a modified Russian-built rocket engine left over from the Soviet moon program apparently triggered the destruction of an Orbital Sciences Antares rocket and a space station-bound Cygnus cargo ship last week seconds after liftoff from Wallops Island, Va., company officials said Tuesday.
Orbital President and CEO David Thompson said the company is accelerating plans to replace the AJ26 rocket engines used in the first five Antares flights with more powerful, and presumably more reliable, motors from an as-yet-unspecified vendor. The upgraded rocket's first flight is expected in 2016, a year earlier than previously planned.
In the near term, Orbital plans to launch one or possibly two Cygnus cargo ships atop rockets built by one or more other companies starting as early as the second quarter of 2015. The "gap-filler" missions and the eventual use of a more powerful version of the Antares will allow Orbital to deliver the cargo originally planned for five missions in just four.
As a result, Thompson said, the company will be able to meet the requirements of its $1.9 billion contract with NASA to deliver some 20 tons of cargo to the International Space Station. And it will do so, he said, at no additional cost to the U.S. space agency.
"By consolidating the cargo of five previously planned (resupply) missions into four more capable ones, we believe we can maintain a similar, or perhaps even a somewhat better, delivery schedule than we were on before last week's launch failure, completing all current (contracted station) cargo deliveries by the end of 2016," he said.
Orbital Sciences is one of two U.S. companies with commercially structured NASA contracts to deliver supplies and equipment to the space station in the wake of the shuttle's retirement. The other is SpaceX, which holds a $1.6 billion contract to launch 12 resupply missions using its Falcon 9 rocket and Dragon cargo craft. SpaceX has launched four operational resupply flights with a fifth set for launch Dec. 9 from Cape Canaveral, Fl.
Last Tuesday, Orbital launched its fifth Antares rocket and the third of eight planned space station resupply missions from the Mid-Atlantic Regional Spaceport at NASA's Wallops Island flight facility. Just 15 seconds after liftoff, the rocket exploded and crashed back to Earth in a spectacular fireball.
Orbital engineers and a team of outside experts on a failure review board have spent the past several days reviewing video and telemetry from the rocket, along with recovered wreckage. While that work is far from complete, Thompson said an initial look indicates an engine failure.
"A very rich set of telemetry and video data has been initially analyzed and a large amount of debris from Antares and Cygnus has been collected and examined," Thompson said. "While still preliminary and subject to change, current evidence strongly suggests that one of the two AJ26 main engines that powered the Antares first stage failed about 15 seconds after ignition.
"At this time, we believe the failure likely originated in or directly affected the turbopump machinery of this engine. I want to stress that more analysis will be required to confirm that this finding is correct."
The Antares first stage engines originally were built for the Soviet Union's ill-fated N-1 moon rocket, a Saturn 5-class booster that never made it to space. When that project was canceled in the early 1970s, left over NK-33 engines were mothballed and later purchased by Aerojet Rocketdyne. The renamed AJ26 engines were refurbished, equipped with modern avionics and extensively tested before their use in the Antares rocket.
But during a test firing last May, an AJ26 suffered a catastrophic failure. After an investigation, Orbital pressed ahead with a July Antares flight, the second operational station resupply mission, after implementing new inspection techniques and analysis. That mission was successful.
But the explosion last week has prompted the company to accelerate plans already in place to re-engine the Antares with a more powerful rocket motor. It has been rumored that Orbital plans to use a Russian engine powered by liquid oxygen and kerosene that is currently in production, but Thompson said he was not yet ready to announce details or identify potential vendors.
"We will accelerate the introduction of Antares upgraded propulsion system, advancing its initial launch date from the previously planned 2017 into 2016," he said. "Consequently, we will likely discontinue the use of the AJ26 rocket engines that have been used on the first five Antares vehicles unless and until those engines can be conclusively shown to be flight worthy."
He did not provide any details about Orbital's contract with Aerojet Rocketdyne or what the engine switch might cost other than to say he did not expect any major, long-term financial impact.
As for the gap-filler missions, Thompson said Orbital was in discussions with three rocket builders, one based in Europe and two in the United States. Again, he declined to identify the potential vendors but said he hoped to finalize plans by the end of the month.
The only two American rocket builders with boosters powerful enough to launch heavier Cygnus cargo ships are SpaceX and United Launch Alliance, a partnership between Boeing and Lockheed Martin that builds Delta and Atlas rockets.
While not identifying potential launchers, Thompson said "indications at this point are favorable that these launch operators do have available capacity that is suitable for Cygnus launches as early as the second quarter of 2015 and extending all the way through mid to late 2016. There are variations among the operators in terms of their specific schedule availability and the payload performance and pricing of their vehicles.
"We believe all the most favorable scenarios not only accomplish our principle objectives with respect to meeting our commitments under the CRS program, but also generally limit the financial impacts to the company. We expect to work with NASA to determine the most favorable combination for one or two gap-filler missions using third party launch vehicles and are aiming to make final decisions on the best way forward over the course of the coming month."
Using the current version of the Antares, the Cygnus cargo ship can carry about 6,000 pounds of equipment and supplies to the space station. The upgraded Antares, and the gap-filler missions, will be able to lift an additional 1,200 pounds or so of cargo per flight.