Following the failure last year of the Antares rocket during the Orb3 resupply mission to the International Space Station Orbital ATK have had to select a different rocket engine for the rocket. They have elected to use the RD-181 engine from Russia company NPO Energomash, they are expecting the first pair to be delivered later this year and will begin integrating them with the first stage replacing the older AJ26.
However the future for the rocket is also contingent on Yuzhmash from Ukraine which supplies the first stage. Due to the on-going conflict in Ukraine it is unknown at this time if Yuzhmash can continue to build the first stages and the longer the conflict goes on the harder it will be to restart and catch up with any backlog the company has as they also supply parts for eight other current or planned rockets..
We reached out to Orbital ATK regarding this situation but have not heard back to determine what options they have, we also don’t know how many of the first stage’s they already had in the US for future Antares flights.
@OrbitalATK – Antares first stage – How many do you currently have? Any issues getting more from Yuzhmash? Do you have alternate supply?
— Chris Marshall (@ChrisDMarshall) March 4, 2015
If we heard back from Orbital ATK we will update the article with any information that is available.