Orbital now has ATK experience on board. Feels natural to switch to all-solid rockets - like other Orbital designs. However for now, the Antares is the biggest

Orbital now has ATK experience on board. Feels natural to switch to all-solid rockets - like other Orbital designs. However for now, the Antares is the biggest Orbital rocket, and it's designed with NK-33. Definitely need to investigate this event and make decisions. It's better to use engines which were just created - or just manufactured - but sometimes there are reasons to prefer old engines to new ones. Age is not the only factor.