LONG BEACH, Calif. — The first launch of an Orbital ATK Antares rocket with a new first stage engine is now planned for early October, a company official said Sept. 13.

Speaking on a launch systems panel during the AIAA Space 2016 conference here, John Steinmeyer, director of business development at Orbital ATK’s Launch Vehicle Division, said the company was working with NASA to finalize a date for the launch, which will carry a Cygnus cargo spacecraft to the International Space Station.

“We’re targeting an initial launch capability in early October. We’re working with NASA to select an optimal launch date,” he said. “We’re very diligent in our preparations for that launch, and making sure we completely validate the system and the RD-181 engines.”

The launch will be the first of a new variant of the Antares, known as the Antares 230. That vehicle replaces the AJ26 engines supplied by Aerojet Rocketdyne, used in the initial Antares missions and implicated in an October 2014 launch failure, with new RD-181 engines from Russian manufacturer NPO Energomash.

An Antares first stage with the RD-181 engines successfully completed a static fire test on the pad at the Mid-Atlantic Regional Spaceport on Wallops Island, Virginia, in late May. NASA and Orbital ATK were planning an Aug. 22 launch of the Antares, but postponed the launch Aug. 10. At the time, the company cited both the schedule of activities on the ISS as well as “continuing processing, inspection and testing” of the Antares for the delay, saying the launch would be rescheduled for the second half of September.

While NASA’s web site still cites a September launch date for the mission, agency spokesman Dan Huot said Sept. 13 that the launch is now planned in three or four weeks.

Steinmeyer, in an interview after the conference session, didn’t go into specifics about any technical issues encountered with the Antares during the static-fire test that may have contributed to the delay, but indicated any problems have been resolved. “We learned things. That’s why we did the test,” he said. “We’ve worked through all that.”

A return to flight for Antares next month, sending a Cygnus spacecraft to the space station, would come as two other ISS cargo vehicles are facing delays. The Japanese space agency JAXA announced Aug. 10 that the launch of an H-2 Transfer Vehicle cargo spacecraft, originally scheduled for Oct. 1, would be delayed because of an air leak in the spacecraft. JAXA has not announced a new launch date for the mission.

SpaceX was scheduled to launch a Dragon cargo spacecraft to the ISS in November, a mission likely to be delayed because of the Sept. 1 pad accident that destroyed a Falcon 9 and its commercial satellite payload. SpaceX executives now say the Falcon 9 could resume launches as soon as November, but have not announced what mission would go on a return-to-flight mission.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...