When the Antares rocket exploded on the launchpad last week, a lot fingers pointed toward its 70s-era Soviet engine. Indeed, Orbital Sciences now confirms a malfunctioning turbopump in the engine was the likely cause of the explosion. The company remains committed to fulfilling its space station resupply contract with NASA, though, likely by buying (newer) Russian rockets.
Turns out, the Antares launch vehicle that exploded during lift-off last week was riding on refurbished disco-era rockets that not even the vaunted Soviet Space Program could manage to get off the ground.
The Antares itself is a product of the Orbital Sciences Corporation. Designed to launch a Cygnus spacecraft with an 11,000 pound payload into low earth orbit as part of a NASA Commercial Orbital Transportation Services Space Act Agreement, the Antares performed four successful spacecraft launches before last week's spectacular failure. Presently, OSC engineers suspect the fault lies within the Antares' first-stage rocket engine: the Aerojet Rocketdyne AJ-26.
The AJ-26 has a bit of a history. Originally named the NK-33, it was actually first developed by the Kuznetsov Design Bureau in the 1970s to lift the Russian NI rocket into space as part of the Soviet Union's ill-fated moonshot attempt. It's a 12-foot tall, 1200-pound liquid oxygen-kerosene turbopump design boasting 338,000 lbf of thrust at sea level. The Soviets spent $1.3 billion and more than a decade developing the NK-33, eventually producing more than 200 of the engines before the Union's fall in 1991.
When the Iron Curtain was raised, all work on the project was halted and the engines themselves were ordered destroyed. However, one enterprising bureaucrat instead spirited the engines to the safety of an undisclosed warehouse where they sat quietly for a number of years before being rediscovered. Aerojet Rocketdyne snapped up 36 of them at $1.1 million apiece in the mid-1990s, renamed them the AJ-26 series, then set about refurbishing the units and refining their engineering—including a new thrust-vectoring gimball block, updated wiring, circuitry, and electromechanical valve actuators—to make the engines more operationally stable.
Per Aerojet Rocketdyne:
The simple design and unique technological approach eliminates exotic materials and complex manufacturing processes, making the engines easy to operate and maintain. The dual AJ26 main engine system provides Orbital Sciences Corporation's Antares vehicle with better performance at a more affordable cost than existing engines in its thrust class.
While these cost saving benefits are impressive, they only really come into play when the engines don't explode six seconds into the mission or, even worse, while they're still in reliability testing. In May of this year, a refurbished AJ-26 destined for use in an future Anteres launch "exploded," according to a NASA report, while sitting in a test stand at Mississippi's Stennis Space Center. So far, OSC has declined to link the two events and is investigating them separately. [Space Travel - AJRD 1, 2 - Wiki - NASA - Space News]