DIRECT advocated developing a single, high-commonality family of rockets named Jupiter, adapted closely from existing Space Shuttle systems. Each Jupiter launch vehicle would use a "common core stage" consisting of a tank structure based closely on the existing Space Shuttle External Tank with a pair of standard four-segment Solid Rocket Boosters (SRBs) mounted at the sides as on the Space Shuttle. Up to four Space Shuttle Main Engines (SSMEs) from the Space Shuttle Orbiter would be attached to the bottom of the External Tank. The engines would be deorbited along with the expended tank to burn up in the Earth's atmosphere.