REMEMBERING NERVA: “Through most of 1966, it was still reasonable to assume that NASA and the United States might enjoy an expansive post-Apollo future off the Earth. Manned missions beyond the moon were expected to evolve from programs already in place; namely, the Apollo lunar landing program, the joint NASA/Atomic Energy Commission NERVA nuclear-thermal rocket program, and the Apollo Applications Program of advanced lunar missions and Earth-orbiting space stations. . . . The hybrid NERVA/nuclear-ion approach would, the MSFC engineers explained, magnify the benefits and mitigate the drawbacks of both propulsion methods. Efficient ion propulsion would slash the amount of the propellant required to reach and return from Mars. This would in turn reduce the number of costly rockets required to place a hybrid Mars spacecraft into Earth orbit for assembly. Five uprated Saturn V rockets would be sufficient to launch a hybrid spacecraft into Earth orbit, or about half as many as required to launch a Mars spacecraft propelled by NERVA nuclear-thermal rocket engines alone.”