Space Shuttle Solid Rocket Booster design or replacing them altogether with liquid "flyback" boosters using either Atlas V or Delta IV EELV technologies. The 5-segment SRB, which would have required little change to the current shuttle infrastructure, would have allowed the space shuttle to carry an additional of payload in an International Space Station-inclination orbit, eliminate the dangerous "Return-to-Launch Site" (RTLS) and "Trans-Oceanic Abort" (TAL) modes, and, by using a so-called "dog-leg maneuver", fly south-to-north polar orbiting flights from Kennedy Space Center. After the destruction of "Columbia", NASA shelved the five-segment SRB for the Shuttle Program, and the three surviving Orbiters, "Discovery", "Atlantis", and "Endeavour"
Space Shuttle retirement for space access systems in the 1970s also, such as the Rockwell "Star-raker" Star-raker was a large single-stage to orbit design that used both rockets and ramjet for propulision. It was a contemporary to the Boeing "Reusable Aerodynamic Space Vehicle", which an all-rocket propulsion single-stage to orbit design. For comparison to an earlier retirement, when the Saturn IB was last flown in 1975 for the Apollo-Soyuz Test Project, the Shuttle development program was already well underway. However, the Shuttle did not fly until 1981, which left a six-year gap in U.S. manned spaceflight. Because of this and other reasons, in