The Saturn C-5N was planned to be a successor to the Saturn V rocket. It would have had a nuclear thermal third stage instead of the S-IVB used on the Saturn V. This change would have increased the payload of the conventional Saturn V to Low Earth orbit from 118,000 kg to 155,000 kg. Learn more about this idea in this article.
After having the Apollo missions successfully reach the moon. The National Aeronautics and Space Administration (NASA) engineers and scientists set their sights on Mars and beyond. The goal was to develop this new technology to visit such faraway places, and Los Alamos would play a key role. The idea was to use a NERVA engine as the third stage of the Saturn V rocket and plausibly reach Mars by 1978 and even use this nuclear engine as the work-horse to establish a large Moon-base colony by 1981.
These new projects were canceled in 1972. And once President Nixon came into office and determined that the Apollo Program and Saturn V rocket were no longer needed to prove US space superiority in the Cold War.
Without the Saturn V rocket, there was no way to place the heavy nuclear engine into space, even though it would dramatically outperform any existing chemical rocket. The nuclear engines would be used as the rocket engines for space ‘towboats’ that would ferry astronauts and cargo from low earth orbit to the moon and beyond.
Even though chemical rockets brought astronauts to the moon and could take them to Mars, there are many shortcomings to the technology. For example, chemical engines offer relatively little power, making astronauts rely on planetary alignments, or so-called “launch windows,” to give a special gravitational slingshot effect that helps catapult space vehicles to space. Furthermore, chemical rockets are slow, making long journeys to places like Mars impractical for human-crewed missions.
Head over to this video where Amy Shira Teitel talks about the nuclear rocket engine NERVA and why they’re awesome in space.
Journey to Mars in Four Months
A more likely technology is nuclear rocket propulsion. Nuclear Saturn V rockets are more fuel-efficient and much lighter than chemical Saturn V rockets. And as a result, atomic-powered rockets travel twice as fast as chemical-driven spacecraft.
Therefore, a nuclear-driven rocket could make a trip to Mars in as short as four months and a journey to Saturn in as few as three years, as opposed to seven years. Such short trip times would help overcome instruments and astronauts’ exposure to harmful radiation emitted from the cosmic rays and solar winds that fill interplanetary space.
The Nuclear Engine For Rocket Vehicle Application – NERVA
The NERVA Program or Nuclear Engine for Rocket Vehicle Application Program was a collective effort between the US Atomic Energy Commission and NASA. The Space Nuclear Propulsion Office managed it.
In 1969, NERVA’s successes spurred NASA-Marshall Space Flight Center director, Dr. Wernher von Braun, to suggest sending 12 astronauts to Mars aboard two rockets. Each propelled by three NERVA rocket engines. That mission would launch in November 1981 and arrive at Mars in August 1982.
Although that mission never took place. The rocket engines tested during that time met nearly all of NASA’s specifications, including those related to thrust-to-weight ratio, thrust, specific impulse, engine restart, and engine lifetime.
When the Project Rover/NERVA program was discontinued in 1972, the only important untested requirement was that a NERVA engine should be able to restart 60 times and run for a total of 10 hours.
The Companies Building the NERVA Engine
Los Alamos Labs had started work on nuclear rockets as early as 1952. This research accelerated so quickly that by the year 1961, the Marshall Spaceflight Center began using nuclear-powered rockets in their planning. The first launch rocket to be in 1964 was a final demonstration of these engines.
Westinghouse and Aerojet built the NERVA engine. The first of those actually constructed and tested in a spaceflight form was the Kiwi-B4 engine that delivered 70,000 pounds of thrust. The NERVA NRX/EST engine in 1966 ran for two consecutive hours.
The NERVA-XE rocket engine tests continued for 115 minutes, and as a consequence, it demonstrated that nuclear rocket engines were now flight-ready as new technology. The nuclear rocket engine program had shown thrusts as high as 250,000 pounds, 90 minutes of constant and controllable thrust delivery, and thermal power equivalent to 4,500 megawatts.
The NERVA Rocket Engine
The engine’s core is the reactor, a cylindrical core consisting of graphite elements impregnated with a Uranium-235 fuel. And inside the center, the fission of uranium atoms is producing heat. And keeping that heat in place is a reflector made of beryllium surrounding the inner core.
Inside the reflector are cooling rods also made of beryllium, but one side is coated with boron. Because the fissioning uranium constantly emits neutrons reflecting back to the core, the heat is sustained and has to be handled.
So, turning the rods with the boron side absorbs the neutrons and reduces the temperature, eventually stopping the reaction. Spinning the rods with the beryllium side sustains the fission reaction.
Hydrogen is deposited supercooled in a liquid state at -420 degrees Fahrenheit above the rocket engine to carry more fuel. The hydrogen is pumped down to the engine nozzle by an external line, though internally passaged back up to the nozzle and then into the reactor, where it passes through tiny channels in the reflector.
This serves the twofold purpose of cooling the engine and heating the hydrogen that it will be in a gaseous state by the time it enters the core.
There Were Plans to Install the NERVA Upper Stage to the Saturn V Rocket
Furthermore, the hydrogen then moves through channels coated with niobium carbide to resist corrosion that runs through the core from top to bottom. And passing through these channels, the hydrogen picks up heat from the fissioning uranium, heating to approximately 4,000 degrees. It then passes through the exhaust nozzle and expands, creating thrust.
A bleed line carries some of the hydrogens back to the turbopump to keep the engine going, making it an incredibly compact and powerful nuclear engine for a deep space mission.
But there are problems as well. Mainly, the high operating temperature and extreme temperature variations make reactors a challenge to both build and operate. That and the crew’s living on a spacecraft propelled by a rocket with nuclear material presented its own problems due to potential exposure.
Although the potential of nuclear propulsion in space was so promising, there were already plans to install the NERVA upper stage to the Saturn V rocket as the base. Exchanging the S-IVB third stage for NERVA would have resulted in 40 to 75 percent more payload landed on the lunar surface than with the chemical Apollo Moon mission. And therefore, with that much power, it would have been a relative breeze to get to Mars.
The Conclusion and End for NERVA Program
The Space Nuclear Propulsion Office intended to build ten nuclear-powered engine-based vehicles. Six engines for ground tests and four for flight tests. However, the development program was delayed after 1966 as NERVA became a political hot potato in the discussion over a Mars mission.
The nuclear-enhanced Saturn V rocket would carry two to three times more extra payload into space than the chemical version. Enough to easily loft 340,000-pound space stations and supply orbital propellant depots.
Eventually, the NERVA program became intimately linked to plans to go to Mars. When Congress finally thwarted at the expense and foolishness of going to Mars, the NERVA program no longer had a ‘customer’ to serve. The NERVA program was subsequently terminated altogether on January 5, 1973.
Thanks for reading this article. If you want to know more about this amazing rocket, then head over to this article named; Why Was The Saturn V Rocket Painted Black And White?