Virtually all space mission plans that use nuclear thermal rockets use derivative designs from the NERVA NRX or Pewee.

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.

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.

They are similar in nature to the nuclear thermal rockets such as NERVA, but are considerably simpler and often have no moving parts.

Given inefficiencies in the heat transfer, the actual NERVA designs were planned to produce about 5 GW, which would make them the largest nuclear reactors in the world.

For the NERVA replacement considered above, this would be 121 kg / s.

SNPO would depend on what was then known as Los Alamos Scientific Laboratory to supply technology for NERVA rocket engines as part of Project Rover.

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.

His Office of Management and Budget ( OMB ) Deputy Director Caspar Weinberger was opposed to this, persuading Nixon to keep the remaining Moon missions, but recommended that if such cancellation would happen that it be " on the ground that Apollo 15 was so successful in gathering needed data that we can now shift, sooner than previously expected, to the Space Shuttle, Grand Tour, NERVA, etc.

The NERVA NRX / XE, judged by SNPO to be the last " technology development " reactor necessary before proceeding to flight prototypes, accumulated over 2 hours of run time, including 28 minutes at full power.

Although the Kiwi / Phoebus / NERVA designs were the only ones to be tested in any substantial program, a number of other solid-core engines were also studied to some degree.

NERVA was considered by the AEC, SNPO and NASA to be a highly successful program ; it met or exceeded its program goals.

Dumbo was similar to KIWI / NERVA in concept, but used more advanced construction techniques to lower the weight of the reactor.

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.

In 1961, the NERVA program ( Nuclear Engine for Rocket Vehicle Applications ) was created.

Marshall Space Flight Center had been increasingly using KIWI for mission planning, and NERVA was formed to formalize the entry of nuclear thermal rocket engines into space exploration.

A 75, 000 lbf ( 334 kN ) thrust baseline NERVA design was based on the KIWI B4 series, and was considered for some time as the upper stages for the Saturn V, in place of the J-2s that were actually flown.

One of the reasons for the cancellation of the NERVA project was the risk of radioactive particles being released in the rocket exhaust, so Hergé's chemical / nuclear combination makes sense.

NERVA is an acronym for Nuclear Engine for Rocket Vehicle Application, a joint program of the U. S. Atomic Energy Commission and NASA managed by the Space Nuclear Propulsion Office ( SNPO ) until both the program and the office ended at the end of 1972.

NERVA demonstrated that nuclear thermal rocket engines were a feasible and reliable tool for space exploration, and at the end of 1968 SNPO certified that the latest NERVA engine, the NRX / XE, met the requirements for a manned Mars mission.

Although NERVA engines were built and tested as much as possible with flight-certified components and the engine was deemed ready for integration into a spacecraft, much of the U. S. space program was cancelled by the Nixon Administration before a manned visit to Mars could take place.

SNPO chose the original 825 second 75, 000 pound-thrust KIWI-B4 nuclear thermal rocket design, named after the Kiwi, a flightless bird native to New Zealand, as the baseline for the 52-inch ( 22 feet from thrust structure to nozzle bottom ) NERVA NRX ( Nuclear Rocket Experimental ).

All test objectives were successfully accomplished, and the first NERVA NRX operated for nearly 2 hours, including 28 minutes at full power.

Without the Saturn S-N rocket to carry the NERVA to orbit, Los Alamos continued the Rover Program for a few more years with Pewee and the Nuclear Furnace, but it was disbanded by 1972.

NASA plans for NERVA included a visit to Mars by 1978 and a permanent lunar base by 1981.

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.

Each year the RIFT was delayed and the goals for NERVA were set higher.

The NERVA stages and living modules are docked together for the trip.

To date, no nuclear thermal rocket has flown, although the NERVA NRX / EST and NRX / XE were built and tested with flight design components.

Hergé's rocket most closely resembles a nuclear thermal rocket, such as the design tested in the United States NERVA project.

This was NASA's first serious foray into nuclear spacecraft propulsion since the cancellation of the NERVA project in 1972.

Diagram of the NERVA nuclear rocket engine

This damages the NERVA upper stage, which catastrophically fails once fired in orbit ; despite returning to Earth safely, the entire crew ( including Ben Priest ) is killed from radiation poisoning, and the space program nearly collapses from hostile political and public opinion against the use of nuclear power in space, and the seemingly unnecessary risks and reasons of a Mars mission.

The second NERVA engine, the NERVA XE, was designed to come as close as possible to a complete flight system, even to the point of using a flight-design turbopump.

The United States tested twenty different sizes and designs during Project Rover and NASA's NERVA program from 1959 through 1972 at the Nevada Test Site, designated Kiwi, Phoebus, NRX / EST, NRX / XE, Pewee, Pewee 2 and the Nuclear Furnace, with progressively higher power densities culminating in the Pewee ( 1970 ) and Pewee 2.

While the NERVA engine was projected to weigh about 6, 803 kg, the final STNP offered just over 1 / 3 the thrust from an engine of only 1, 650 kg by improving the I < small >< sub > sp </ sub ></ small > to between 930 and 1000 seconds.

A test of the NERVA is finally launched atop one of these, called Apollo-N, but suffers from pogo oscillations in the S-IC first stage.

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 name was a play on the larger systems being developed under Project Rover, which led to NERVA.

At the same time, the NERVA program is revived to become the chosen Mars spacecraft development, with larger tests in Nevada, but without containment and plagued with engineering problems.

Although Los Alamos tested several KIWI and Phoebus engines during the 1960s, testing of NASA's NERVA NRX / EST ( Engine System Test ) contractor engine didn't begin until February 1966.