RD-180 - Credit: Lockheed Martin. 14,267 bytes. 189 x 227 pixels.

Atlas booster and sustainer engine arrangement replaced by Glushko engines developed for Zenit. Not capable of single stage to single stage to orbit capability (an Internet spaceflight urban myth). The single-stage Atlas IIIA booster uses a high-performance RD-180 propulsion system produced by a U.S./Russian joint venture (RD AMROSS) comprised of Pratt & Whitney (U.S.) and NPO Energomash (Russia). The RD-180 burns liquid oxygen and RP-1 propellant and develops a lift-off (sea-level) thrust of 2.6 MN. The RD-180 throttles to various levels during atmospheric ascent to effectively manage the air-loads experienced by the vehicle enabling minimum Atlas vehicle and launch site infrastructure changes. Additionally, throttling results in satellite experienced flight environments that are nearly identical to Atlas IIAS.