Orbital Sciences Corp. could accelerate a plan to re-engine the Antares main stage if the cause of an Oct. 28 launch failure is attributed to the rocket’s twin AJ-26 engines.

Based on NK-33 powerplants developed by Russia’s Kuznetsov Design Bureau in the 1990s, the AJ-26 is a LOX/kerosene propulsion system developed specifically for the Antares launcher by Aerojet Rocketdyne of Sacramento, California.

But with a dwindling supply of the engines in U.S. inventory, Orbital has been seeking a replacement for the core stage of the Antares rocket, which along with the company’s Cygnus cargo carrier is expected to deliver 20,000 kg of supplies and experiments to the International Space Station (ISS) by 2017 under a $1.9 billion commercial resupply services (CRS) contract with NASA.

Orbital CEO David Thompson says that in addition to future supply concerns, the AJ-26 suffers from technical issues, including a fire that occurred during ground tests at NASA’s Stennis Space Center in Mississippi earlier this year.

"As you know, the AJ-26 engines have presented us with serious technical and supply challenges in the past, so notwithstanding the previous successful flights of Antares before yesterday, Orbital has been reviewing alternatives since the middle of last year and recently selected a different main-stage propulsion system for future use," Thompson said in an Oct. 29 conference call with Wall Street analysts. "One possibility is we may decide to accelerate this change if the AJ-26 turns out to be implicated in the failure, but this has not yet been decided."

Thompson said under the company’s original plan, it expected to spend roughly two years re-engining the Antares core stage.

"I certainly think we can shorten that interval, but at this point I don’t know how much," he added.

Following a smooth countdown, Antares lifted off Oct. 28 from its Wallops Island launch pad on Virginia’s eastern shore, en route to the ISS. Approximately 15 sec. into the flight the rocket experienced a catastrophic failure that destroyed it and the Cygnus cargo carrier attached to it, raining debris on the launch pad and nearby beaches.

Thompson said no one was injured as result, and based on a preliminary inspection conducted this morning at Wallops, the launch pad itself was spared major damage.

In addition, he said the Antares vehicle assembly building and related Cygnus spacecraft processing facilities at other locations in the Wallops area were not affected by the failure.

Thompson commented that based on preliminary data, he had a sense of what may have caused the mishap. He said while the investigation would need "days, not weeks," to narrow down a list of possible causes, it may take "a little longer than that to zero-in on the final root cause."

With Orbital’s next cargo run to the ISS slated for spring, he said the mission is likely to be delayed a few months, but could potentially slip one year.

"I would anticipate that there will be some delay in the next scheduled Antares launch, which as I mentioned earlier is set for early April," Thompson said. "I think a reasonable best-case estimate would bound that at three months, but it could certainly be considerably longer than that depending on what we find in the review. I hope it would be not more than a year."

Thompson said the failed launch marked the first flight of an upgrade to the Antares system that included improvements to the solid-fueled Castor upper stage built by Virginia-based Alliant TechSystems (ATK).

However, he explained that "we have absolutely no reason at this point to have any concerns about the performance of that new second stage. . .nothing that would suggest that’s a contributor in any way."

For now, Thompson said, the mishap also has no bearing on the proposed merger of Orbital and the aerospace and defense divisions of ATK, though he did not directly address whether a Dec. 9 shareholder meeting scheduled to vote on the merger would be delayed.

He expects the incident to have minimal impact on the company’s earnings, noting that the Cygnus cargo carrier accounts for a larger share of the company’s CRS revenue than Antares.

"In the very near-term, receivables that would have been collectable upon completion of a successful mission a month or so from now will be covered instead by mission insurance," Thompson said. "We had not anticipated the collection of that receivable until January in any case, so we should have no effect one way or another on the final quarter of the year."

He said receivables on other missions beyond the ill-fated launch attempt will depend on progress both in building the Cygnus spacecraft as well as completing milestones on the launch vehicles, which he expects to continue.

"Some of those could be affected as a function of delays that could be incurred for launches scheduled in 2015," he said. "At this point we don’t have a precise estimate on the magnitude of how that might vary, but we’re working to put one of those together in the next couple days."

In the meantime, Thompson said, the company remains on track to submit a bid under NASA’s follow-on CRS contract due next month.

"We intend to as quickly as we can bounce back from this failure and to continue both under the current contract and hopefully a future contract as well, to provide an important part of the cargo bridge from Earth to space in support of NASA’s human spaceflight program," he continued. "It’s still full speed ahead on pursuit of future business."

However, when pressed for details of the engine selection for the Antares main stage, announced Oct. 16 during a third-quarter earnings call with investors, Thompson declined to offer specifics. But he suggested the mishap could be a blessing in disguise, as the potential to accelerate Antares re-engining could attract new business.

"On a failure like this for a launch vehicle still relatively early in its life-cycle, it is not helpful in a general sense," he said. "On the other hand, the possibility of an earlier introduction of the new main-stage propulsion system may actually be a positive development. How those two factors net out is too early to tell, and they vary depending on the circumstances of different customers."

Although Orbital has said little about AJ-26 replacement options, Aerojet Rocketdyne has for years proposed restarting Russian production of the NK-33, which it would continue to modify for Antares and potentially other customers.

More recently, Thompson said Orbital was weighing a solid-rocket-motor solution proposed by ATK.

A third option could be the Russian RD-180 used to power the core stage of the United Launch Alliance (ULA) Atlas 5. Last year Orbital sued ULA and Russian engine maker RD Amross in U.S. District Court for the Eastern District of Virginia, alleging U.S. antitrust violations over ULA’s exclusive use of the LOX/kerosene engine.

Orbital dropped the lawsuit in early 2014, and more recently reached a settlement with RD-Amross, according to an Oct. 23 SEC filing. However, the company is still in talks with ULA over access to the RD-180.

"We are attempting to negotiate a business resolution with ULA for our access to the RD-180 rocket engine, subject to all necessary approvals from the U.S. and Russian governments," Orbital said. "If a mutually agreeable resolution is not reached, we will have the option to refile our lawsuit against ULA."

In the meantime, Thompson said despite the launch failure there is an adequate supply of AJ-26 engines in U.S. inventory to execute the company’s commitment under its initial CRS agreement with NASA, including a recent one-year contract extension that was necessary for both Orbital and competitor Space Exploration Technologies (SpaceX) to meet their obligations.

"There are adequate AJ-26 engines in inventory which, subject to ground testing and flight-worthiness determinations, would fulfill all of our commitments under the current contract," he said.

Meanwhile, the company is considering several options for meeting its immediate obligation to NASA, though Thompson declined to be specific.

"We want to look at all alternatives to minimizing any disruption at all, if that’s possible. So we’re going to consider several possibilities and I would guess sometime maybe in November we’ll largely have settled on a course forward," Thompson said. "It may be staying on the current configuration, it may be accelerating a new configuration, or it may be a few variations on one or more of those themes."