UPDATE, October 23, 2016: Cygnus OA-5 was successfully berthed to the ISS this morning as planned.

ORIGINAL STORY, October 18, 2016: Orbital ATK’s Antares rocket is back in service after a successful launch five hours ago from Wallops Island, VA. The rocket delivered a Cygnus cargo spacecraft to orbit. Cygnus will be berthed to the International Space Station (ISS) on Sunday after an extended period of independent flight while a new crew arrives.

The 7:40 pm ET launch on October 17 from the Mid-Atlantic Regional Spaceport (MARS) at NASA’s Wallops Flight Facility slipped to 7:45 pm ET, the end of the 5-minute launch window. A commentator on NASA TV said at the time it was due to a minor engine problem. At a post-launch press conference, however, Orbital ATK’s Frank Culbertson said it was to give the launch crew one last chance to check everything over according to a tweet from Jeff Foust (@jeff_foust) of Space News.

Whatever the reason for the brief delay, the launch appeared flawless when it took place.



Antares Liftoff on Orbital ATK Cygnus OA-5 Mission, October 17, 2016. Photo Credit: NASA Wallops/Patrick Block

This is first flight of Antares since a failure almost exactly two years ago (October 28, 2014). In the intervening time, Orbital ATK replaced the old Russian NK-33/AJ26 engines with newer Russian RD-181 engines.

The launch was delayed many times since this spring, most recently from Sunday to Monday. It is designated OA-5, for Orbital ATK-5, even though OA-6 already has been launched. While Antares was being re-engined, Orbital ATK launched two Cygnus cargo spacecraft on United Launch Alliance Atlas V rockets. OA-4 was launched in December 2015 and OA-6 in March 2016. This mission was intended to launch in between those, hence the non-sequential numbering.

If this launch had taken place as planned on Sunday, Cygnus OA-5 would have gone directly to the ISS and been berthed there on Wednesday. Because of the one-day delay, however, it will have to wait until Sunday because a new ISS crew (Soyuz MS-02) will be launched on Wednesday and dock on Friday. NASA wants to wait for that to occur and the new crew to have a day to acclimate. Cygnus will be grappled using the robotic Canadarm2 at about 7:05 am ET on Sunday and berthed to an ISS port about two hours later.