Atlas III

The Atlas III (known as the Atlas II-AR (R for Russian) early in development) was an American orbital launch vehicle, used in the years between 2000 and 2005. It was the first member of the Atlas family since the Atlas A to feature a "normal" staging method, compared to the previous Atlas family members, which were equipped with two jettisonable outboard engines on the first (booster) stage (with a single center engine serving as the sustainer). The first stage engines were Russian RD-180s, which are also used by the Atlas V. The Atlas III was produced in two versions. The baseline was the Atlas IIIA, but the Atlas IIIB, featuring a twin-engine version of the Centaur upper stage, was also produced.