Space transportation requirements are major elements in the technical and economic realization of the entire SPS concept. First, steps in enhancing the shuttle include the Titan based liquid boost module (LBM) and liquid propellant boosters (LPB) to replace the present solid rocket boosters (SRB). The next choice between new ballistic or winged boosters must still be made; as well as the choice between series (staged) and parallel operation. Entirely new vehicles of large size are required before the economic and environmental problems of the prototype, or even demonstration, SPS can be resolved. Social impacts such as noise, and atmospheric pollution, locally and in the ionosphere, must be fully addressed. Although rather advanced technology and well developed operational management is required to properly target the average cost of gross cargo payloads into LEO at 30 (1979)/kgfortheconstructionoftheinitialSPS,thefurthergoalforrepetitiveconstructionof30to60SPSat15 (1979)/kg for all operational payloads require the use of very advanced, long lived vehicles with a sophisticated operational organization using off shore, equatorial launch sites
