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Orbital Sciences turns to Atlas rocket to fill gap in station cargo launches

Irene Klotz, Spaceflight Correspondent
Dec 16, 2014, 5:56 UTC

Sen—With its Antares rocket grounded, Orbital Sciences will buy rides for up to two Cygnus cargo ships on United Launch Alliance (ULA) Atlas 5 rockets.

Orbital Sciences meanwhile hopes to have its Antares rocket flying again in early 2016.

The company’s fifth Antares rocket launch ended in an explosion about 15 seconds after liftoff on 28 October from the Wallops Island Flight Facility in Virginia. The cause of the accident is under investigation, but preliminary findings indicate a problem with a main-engine turbopump. The accident claimed a Cygnus cargo capsule bound for the International Space Station.

The engines are refurbished Soviet-era NK-33 motors, originally manufactured for the failed N1 moon rocket. Aerojet Rocketdyne purchased the leftover motors, which had been in storage for 20 years, and refurbished them for resale in the United States as AJ-26 engines.

Orbital Sciences has not yet announced what engine will replace the AJ-26, but Russian news agencies have reported that another Russian engine, the RD-193 built by NPO Energomash, was the leading candidate.

The engine upgrade was planned prior to the 28 October Antares launch failure.

To fulfill its contractual commitment to deliver cargo to the International Space Station for NASA, Orbital Sciences will purchase launch services for at least one Cygnus capsule on an Atlas 5 rocket slated to fly in late 2015.

“We could not be more honored that Orbital selected ULA to launch its Cygnus spacecraft,” said ULA vice president Jim Sponnick said in a statement. “This mission was awarded in a highly competitive environment, and we look forward to continuing ULA’s long history of providing reliable, cost-effective launch services for customers.”

Orbital Sciences said last month that it was considering two U.S.-based and one European launch services companies to bridge the gap until its Antares rocket returned to flight.

The companies are presumed to be ULA, Space Exploration Technologies, or SpaceX, and Arianespace. SpaceX has a separate NASA contract to fly cargo to the space station.

“Orbital is pleased to partner with ULA for these important cargo missions to the International Space Station,” Orbital Sciences executive vice president Frank Culbertson said in a statement.

“ULA’s ability to integrate and launch missions on relatively short notice demonstrates ULA’s manifest flexibility and responsiveness to customer launch needs,” Culbertson added.

Terms of the contract were not disclosed. Orbital Sciences said the agreement includes an optional second flight in 2016 if its revamped Antares is not yet ready to fly.

Orbital Sciences originally planned to handle its $1.9 billion contract for carrying at least 20 metric tons to the station in eight flights, two of which have been successfully completed. 

Now, the company expects to be able to fly 35 per cent more cargo per flight on the heavier lift Atlas rocket and on its upgraded Antares booster, fulfilling its contract with four more launches.

Flying on an Atlas gives ULA a preview of planned upcoming missions to the space station as a partner in NASA’s Commercial Crew program. The Atlas 5 is the booster of choice for Boeing’s CST-100 passenger spaceship, which is expected to begin flying crews to the station before the end of 2017.