It seems that Orbital ATK would like to prepare as best as possible first launch of their heaviest rocket Antares. After almost two years break launch of their heaviest rocket will be probably delayed.
Upgrading Antares with new engines was one of most important plans of Orbital ATK for 2016. After disaster on 28 October 2014, when Antares rocket exploded over Wallops Flight Facility in Virginia shortly after liftoff, Orbital ATK was forced to seek launch service provider to meet the assumptions of contract for resupply services signed with NASA. Upgraded Antares with Cygnus on atop (OA-5 mission) was scheduled previously for May/June 2016 but was postponed to 6th July 2016. Now it is possible that rocket will start not earlier then August 2016.
New upgraded Antares, marked as Antares 200, had new propulsion. NK-33 engines modified by Yuzhnoye Design Bureau were replaced by RD-181 engines made by Energomash in Russia; it is combined with Castor-30XL solid fueled (HTPB) second stage. Static fire test of the first stage (first stage which was tested was not exact same stage which will be used in OA-5 mission, but it will be utilized for planned for 30th December 2016 OA-7 resupply mission) was performed in Wallops at 21:30 GMT on 31 May 2016. Test was passed successfully and Orbital ATK did not announced about any kind of problems which could delay launch planned for July. Short analysis of data shortly after test also did not show any problems, what was officially confirmed by Orbital ATK General Manager Mike Pinkston:
“Early indications show the upgraded propulsion system, core stage and launch complex all worked together as planned,”
Both rocket and propulsion were operating according to assumptions, but Orbital ATK planned further data analysis and in case where results would be positive, it was planned to start preparing OA-5 mission for 6th July 2016. Unfortunately it seems that launch of Antares will be postponed. According to Nasaspaceflight.com some problems were spotted after analysis of data from static fire test. Vibrations on the stage structure were spotted and it was necessary to perform additional corrections in the avionics; now changes need to be approved and implemented into rocket. Details on modification sand characteristic of vibrations were not unveiled. Orbital ATK also confirmed that OA-5 mission is still under preparation but it is more possible that it will be launch in August.