NERVA - in The Space Program

In The Space Program

NASA plans for NERVA included a visit to Mars by 1978 and a permanent lunar base by 1981. NERVA rockets would be used for nuclear "tugs" designed to take payloads from Low Earth Orbit to larger orbits as a component of the later-named Space Transportation System, resupply several space stations in various orbits around the Earth and Moon, and support a permanent lunar base. The NERVA rocket would also be a nuclear-powered upper stage for the Saturn rocket (the Saturn S-N), which would allow the upgraded Saturn to launch much larger payloads of up to 340,000 pounds to Low Earth Orbit.

NERVA rockets had progressed rapidly to the point where they could run for hours, limited in run time by the size of the liquid hydrogen propellant tanks at the Jackass Flats test site. They also climbed in power density. The larger NERVA I rocket gradually gave way to the smaller NERVA II rocket in mission plans as efficiency increased and thrust-to-weight ratios grew, and the KIWI gradually gave way at Los Alamos to the smaller Pewee and Pewee 2 as funding was cut to lower and lower levels by Congress and the Nixon administration.

The RIFT vehicle consisted of a Saturn S-IC first stage, an SII stage and an S-N (Saturn-Nuclear) third stage. The Space Nuclear Propulsion Office planned to build ten RIFT vehicles, six for ground tests and four for flight tests, but RIFT was delayed after 1966 as NERVA became a political proxy in the debate over a Mars mission. The nuclear Saturn C-5 would carry two to three times more payload into space than the chemical version, enough to easily loft 340,000 pound space stations and replenish orbital propellant depots. Wernher von Braun also proposed a manned Mars mission using NERVA and a spinning donut-shaped spacecraft to simulate gravity. Many of the NASA plans for Mars in the 1960s and early 1970s used the NERVA rocket specifically, see list of manned Mars mission plans in the 20th century.

The Mars mission became NERVA's downfall. Members of Congress in both political parties judged that a manned mission to Mars would be a tacit commitment for the United States to decades more of the expensive Space Race. Manned Mars missions were enabled by nuclear rockets; therefore, if NERVA could be discontinued the Space Race might wind down and the budget would be saved. Each year the RIFT was delayed and the goals for NERVA were set higher. Ultimately, RIFT was never authorized, and although NERVA had many successful tests and powerful Congressional backing, it never left the ground.