NERVA; What it was, and what it could be in the near-future.

| NERVA and what it was |

In 1968, NASA coming out of Project Rover, decided it was high time to delve into the nuclear power fever that had stricken America for the last few decades to use it to their advantage. To reach that goal, engineers at Aerojet, Westinghouse, and LASL (Los Alamos Scientific Laboratory), under the banner of NASA, collected some engine bells from Rover (made from 1955-73), used the testing facility in Jackass Flats, and bore the NERVA program. Standing for Nuclear Engine for Rocket Vehicle Application, the NERVA program was made for application to the S-IVB or future vehicles, mainly for trans-martian travel, and maybe farther. 

Image: NERVA engine in flight pictured in Kerbal Space Program. Source: Zorg2099

| Engine Specifications and Fuels |

The engine had a length of 6.9 m (23’), a diameter of 2.59 m (8’6”), and a dry mass of ~18,000 kg (~40,000 lbs). The reactor itself was a solid-fuel highly enriched U-235. It had a graphite-moderator, in a Control Drum setup. The engines were fueled by LH2, and also used it as the main coolant. The thermal power outputs were in the 1,130 mW range. All of the reactors and engines made were made with flight-ready materials, meaning at any point NASA could’ve mounted an engine on a S-IVB and it most likely would’ve worked, but the testing and honing of the technology was very important before having a test flight staged. All the engines that were constructed (Kiwi, NERVA XE, and NERVA NRX) were made based off of the Kiwi engines from the prior Project Rover, but expanded upon under the NERVA banner. 

Image: Technicians in a vacuum furnace at Lewis’ Fabrication Shop prepare a Kiwi B-1 nozzle for testing in the B-1 test stand. Source: NASA

| The final years of NERVA |

After all the engines were made and tested, what became of the program? NASA was planning too much, and the Vietnam War was draining money and political favor. NASA had been planning on trips to Mars and bases on the Lunar surface by the 70’s-80’s, and the ever encroaching Vietnam War was draining the US Government’s budgets. NERVA II was defunded in ‘67, and while the aftermath caused a mess of refundings and defundings and presidential contingency funds, it all ended in NERVA I’s funding being restored temporarily, but it didn’t last for too long, as after 17 years of R&D, NERVA was officially canned. 

Image: A render of the DRACO engine. Source: Lockheed Martin

| The NTR concept in the near-future |

In the end, NERVA ended up being revisited by NASA a few times for missions to Mars, but nothing came of it. Until recently, nuclear engines were on the back burner for most of the other missions that took precedence over it, but now, Lockheed Martin is launching one. DRACO, standing for Demonstration Rocket for Agile Cislunar Operations, will launch on a Vulcan-Centaur on a demonstration test by 2026-2027. The Nuclear Thermal Rocket concept has a steady chance of becoming something used by long-distance interplanetary missions. DRACO will be setting the NTR concept up for either a short life, or a long lived legacy.