Marshall Space Flight Center (MSFC) workers lower S-IB-200D, a dynamic test version of the Saturn IB launch vehicle's first stage (S-IB stage), into the Center's Dynamic Test Stand on January 12, 1965. Test Laboratory persornel assembled a complete Saturn IB to test the structural soundness of the launch vehicle. Developed by the MSFC as an interim vehicle in MSFC's "building block" approach to Saturn rocket development, the Saturn IB utilized Saturn I technology to further develop and refine large boosters and the Apollo spacecraft capabilities required for the manned lunar missions.