We live in an era of renewed exploration, where many organizations are planning to send astronauts to the Moon in the coming years. This will be followed in the next decade by NASA and China’s expeditions to Mars, which may be joined by other nations before long.
These and other missions that will take astronauts beyond Low Earth Orbit (LEO) and the Earth-Moon system will require new technologies, from life support and radiation shielding to power and propulsion.
And when it comes down to it, Nuclear Thermal and Nuclear Electric Propulsion (NTP/NEP) is a top contender!
NASA and the Soviet space program spent a decade researching nuclear power through the Space Race.
A few years ago, NASA took its nuclear program to develop a bimodal nuclear propulsion system – a dual system consisting of an NTP and a NEP element – that could enable a Mars transit in 100 days.
As part of NASA’s Innovative Advance Concepts (NIAC) 2023 program, NASA has selected a nuclear concept for Phase I development. This new type of bimodal nuclear propulsion system uses a “shear wave rotor cycle” and can reduce transit times to Mars by as little as 45 days.
The presentation entitled “Bimodal NTP/NEP with Wave Rotor Topping Cycle” was presented by Prof. Ryan Gosse, Hypersonic Area Program Lead at the University of Florida and a member of the Florida Research in Engineering (FLARE) team.
Gosse’s proposal is one of 14 NAIC selected this year for Phase I development, which includes a US$12,500 grant to help mature technology and methods. Other innovative proposals included sensors, instruments, manufacturing techniques, power systems, and more.
frameborder=”0″ allow=”accelerometer; autoplay clipboard-write; encrypted media; gyroscope; picture-in-picture; web-share “allowfullscreen>
Nuclear propulsion essentially comes down to two concepts, both of which are based on clear and powerful technologies.
For Nuclear-Thermal Propulsion (NTP), the cycle consists of the nuclear reactor heating the liquid hydrogen (LH2) propellant, turning it into a gas (plasma) of ionized hydrogen, which is then introduced through the nozzles to generate the thrust.
There have been several attempts to build this propulsion system, including Project Rover, a collaborative effort between the US Air Force and the Atomic Energy Commission (AEC) that was launched in 1955.
In 1959, NASA took over from the USAF, and the program entered a new phase dedicated to space applications. This eventually led to the Nuclear Engine by Rocket Vehicle application (NERVA), a solid nuclear reactor that was successfully tested.
With the Apollo Era closing in 1973, the program was curtailed, leading to its cancellation before any flight tests could be conducted. Meanwhile, the Soviets developed their NTP concept (RD-0410) between 1965 and 1980 and conducted one trial before testing the new board.
Nuclear-electric propulsion (NEP), on the other hand, relies on a nuclear reactor to provide electricity in a Hall-Effect impulse (ion engine), which generates an electromagnetic field that ionizes and accelerates an inert gas (like xenon) to create. he pushed Initiative (NSI) Project Prometheus (2003 to 2005).
Both systems have significant advantages over conventional chemical propulsion, including a higher impulse (Isp) rating, fuel efficiency, and nearly unlimited energy density.
While the Nep concepts are distinguished at more than 10,000 Isp seconds, meaning they can maintain an impact for close to three hours, the level of impact is quite low compared to conventional rockets and NTP.
The need for the principle of electrical power, says Gosse, also drives the flow of heat rejection in space – where thermal energy conversion is 30-40 percent under ideal circumstances.
While NTP NERVA designs are the preferred method for navigation missions to Mars and beyond, this method also has issues with adequate initial and final mass fractions for high altitude missions.
This is why proposals that include both propulsion methods (bimodal) are encouraged to combine the advantages of both. Gosse’s proposal calls for a bimodal design in a solid core NERVA reactor that should provide a specific impulse of 900 seconds (Isp) of 900 seconds, twice the current performance of chemical rockets.
The proposed Gosse cycle also includes a supercharger pressure wave or Wave Rotor (WR) – a technique used in internal combustion engines that combines the pressure wave through the movement of compressed air.
When paired with an NTP engine, the WR would use the pressure created by the heat of the LH2 reactor fuel to further compress the reaction mass. As Gosse promises, this will give an impulse level comparable to the NERVA-NTP concept, but with 1400-2000 Isp seconds. When the nep cycle is joined, said Gosse, the levels of impact are increased even further;
“Coupled with the Nep cycle, the duty cycle of the Isp can be further increased (1,800-4,000 seconds) with a minimal addition of dry mass. This bimodal design allows a fast transition for fixed missions (45 days to Mars) and will enable deep exploration of our solar space.”
Based on conventional propulsion technology, a troubled Mars mission could last up to three years. These missions all take 26 months, when Earth and Mars are in close (aka. Mars opposition) and will take at least six to nine months in transit.
A transition of 45 days (six and a half weeks) would reduce the overall mission time to months instead of years. This will significantly reduce the major risks associated with missions to Mars, including radiation exposure, time spent in microgravity, and related health concerns.
In addition to propulsion, there are proposals for new reactor designs that would provide a stable power supply for long-duration surface missions where solar and wind power are not always available.
Examples include NASA’s Kilopower Reactor of Sterling Technologies (KRUSTY) and the hybrid fission/fusion reactor selected for Phase I development by NASA’s NAIC 2023 selection.
These and other nuclear applications could one day enable missions to Mars and other places in deep space, perhaps sooner than we think!
This article was first published by Universe Today. Read the original article.
#NASA #Nuclear #Rocket #Plan #Aims #Mars #Days
