Orbital Sciences picks another Russian engine for Antares

The heat of competition: In its effort to replace the old Cold War Soviet-era refurbished Russian engines for the first stage of its Antares rocket, Orbital Sciences today announced that it will instead buy a different modern-built Russian engine.

Designated the RD-181, the new engine will be used on Antares in shipsets of two to accommodate as closely as possible the two-engine configuration built around the AJ-26 engines supplied by Aerojet Rocketdyne, Orbital Sciences managers said Dec. 16. A descendant of the RD-171 that powers the Ukrainian-built Zenit launch vehicle, the RD-181 will be manufactured in the same Khimki factory that builds the RD-180 used on the United Launch Alliance Atlas V. It closely resembles the RD-191 on Russia’s new Angara launcher and the RD-151 that powers South Korea’s Naro-1 launch vehicle.

It appears that this is the only engine presently available that can do the job. In the long run however it puts Antares and Orbital Sciences at a competitive disadvantage. Even though the sanctions against using Russian engines, passed by Congress, only apply to military launches, Orbital’s continuing reliance on Russian engines will limit their customer base.