Orbital Sciences Corp. today officially scheduled July 11 for the next launch of their Antares rocket on the company’s second NASA-contracted resupply flight to the International Space Station (ISS) after inspections of the rocket’s AJ26 engines revealed no problems. The launch date has been repeatedly delayed recently, pending the outcome of an investigation into why an Antares AJ26 engine scheduled to fly an ISS flight next year failed during customary acceptance testing (also known as “hot-fire” testing) at NASA’s Stennis Space Center in Mississippi on May 22.
“The engineering team that is investigating the failure of an AJ26 engine during an acceptance test at Stennis Space Center recommended that certain inspections be performed on the two AJ26 engines that are currently integrated on the Antares rocket,” explained Orbital Sciences in a statement released this morning. “These inspections were recently completed and program officials have cleared the rocket for flight.”
The Cygnus spacecraft tasked with delivering over 3,650 pounds (1,657 kg) of cargo and supplies to the ISS will be mated to its two-stage Antares launch vehicle today, and the 131-foot-tall rocket with its spacecraft will be rolled out to launch pad 0A at the Mid-Atlantic Regional Spaceport on July 9.
Antares has flown flawlessly on all three of its missions since 2013, but the liquid kerosene- and liquid oxygen-powered AJ26 engines Orbital Sciences uses to launch Antares skyward have failed in testing before, most recently in June 2011 when an engine caught fire on the Stennis E-1 Test Stand due to leaking kerosene in an engine manifold. The engines are actually modified Russian NK-33s, reconditioned by Aerojet Rocketdyne specifically for Antares.
A U.S.-built version of the AJ-26 engine is currently being developed in a strategic partnership between Aerojet and Teledyne Brown for NASA’s future Space Launch System (SLS).
It’s important to note that the engines themselves, built by Kuznetsov Design Bureau, are 40 years old, and they are no longer in production. Aerojet purchased 40 of the engines in the 1990s and can supply enough to Orbital to support Orbital’s contractual obligation for ISS resupply flights for NASA—for now—but without a replacement engine the Antares may not survive to fly into the next decade. In an effort to secure future exclusive business with Antares Aerojet president William Boley offered to restart engine production with Kuztnetsov last year, with the goal of producing four to six new engines annually in time to support NASA’s future CRS-2 contract (delivery of the new engines would need to start in 2016 to support that). How those talks have gone in the time since is unclear at this time.
The upcoming mission, dubbed Orb-2, will be only the second of eight such scheduled flights for Orbital under a $1.9 billion Commercial Resupply Services (CRS) contract with NASA. Cygnus will remain at the ISS for 40 days before burning up in the Earth’s atmosphere with over 3,500 pounds of garbage.
The mission will mark the third ISS flight for Orbital and the fourth flight of their Antares rocket (third flight for Cygnus).
AmericaSpace will provide full on-site coverage of the launch when it occurs, so check back regularly for updates.