Atlas IIIA

The Atlas III (known as the Atlas II-AR early in development) was an American orbital launch vehicle used 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).

Atlas III was operated by Lockheed Martin.