CAPE CANAVERAL, Aug 12 (Reuters) - Orbital ATK Inc is buying a second Atlas rocket launch to fly supplies to the International Space Station for NASA while it redesigns its Antares booster following a launch accident last year, the aerospace company said on Wednesday.
The Oct. 28 accident, which occurred seconds after launch from Virginia's Wallops Island, destroyed a Cygnus capsule filled with cargo bound for the space station. A final report on the accident is pending.
In December, Orbital said it had bought an Atlas rocket launch from United Launch Alliance, a partnership of Lockheed Martin Corp and Boeing Co, to help fulfill its $1.9 billion cargo delivery contract with NASA while it recovers from the accident.
Terms of the contract were not disclosed. The launch is targeted for early December from Cape Canaveral Air Force Station in Florida to the space station, a permanently staffed, $100 billion research laboratory that flies about 250 miles (400 km) above Earth.
After the accident, Orbital also advanced plans to replace Antares' troubled Soviet-era engines with new Russian-made RD-181 motors. The refurbished rocket is expected to be ready to fly in early 2016, with one or two more missions to follow that year, Orbital said.
The purchase of a second Atlas launch for a station resupply mission in 2016 will give Orbital some flexibility to deliver the maximum amount of cargo to the station under terms of its NASA contract, said Orbital spokeswoman Trina Helquist.
Both the Atlas and the revamped Antares rockets can carry heavier loads than the original Antares, so Orbital expects to be able to fulfill its contract with fewer than the eight launches called for in its original agreement with NASA. Orbital completed two station cargo runs prior to last year's accident.
NASA has a second space station resupply contract with privately owned SpaceX, which is recovering from an unrelated June 28 launch accident of its Falcon 9 rocket.
A third supply line to the station operated by Russia reopened last month following a botched Soyuz rocket flight on April 28. A fourth cargo ship flown by Japan is due to launch on Sunday. Europe's ATV cargo ships have been retired. (Reporting by Irene Klotz; Editing by Bill Rigby)