Comparing Nuclear Propulsion Technologies for Crewed Missions to Mars Current chemical propulsion systems are limited in their ability to support crewed missions to Mars due to their low propellant efficiency and long mission times. Nuclear propulsion technologies offer a potential solution to these challenges, as they are capable of producing higher thrust and propellant efficiency than chemical rockets. This paper compares three nuclear propulsion technologies for crewed missions to Mars: nuclear electric propulsion (NEP), nuclear thermal propulsion (NTP), and nuclear fusion propulsion (NFP). Each technology has its own advantages and disadvantages, and the best choice for a crewed Mars mission will depend on a number of factors, including mission requirements, cost, and risk. NEP systems are the most mature of the three technologies, and they have already been used successfully in a number of space missions. NEP systems use a nuclear reactor to generate electricity, which is then used to power an electric thruster. NEP systems are very efficient, but they produce relatively low thrust. As a result, NEP systems require longer mission times than other nuclear propulsion technologies. NTP systems are less mature than NEP systems, but they offer the potential for higher thrust and shorter mission times. NTP systems use a nuclear reactor to heat a propellant gas, which is then expelled through a nozzle to produce thrust. NTP systems are more efficient than chemical rockets, but they are also more complex and expensive to develop. NFP systems are the most advanced of the three technologies, but they are also the most speculative. NFP systems would use the fusion of atomic nuclei to generate energy, which could then be used to power a variety of propulsion systems. NFP systems have the potential to offer even higher thrust and shorter mission times than NTP systems, but they are still in the early stages of development.

Nuclear power is the next enabling technology in manned exploration of the solar system. Scientists and engineers continue to design multi-megawatt power systems, yet no power system in the 100 kilowatt, electric range has been built and flown. Technology demonstrations and studies leave a myriad of systems from which decision makers can choose to build the first manned space nuclear power system. While many subsystem engineers plan in parallel, an accurate specific mass value becomes an important design specification, which is still uncertain. This thesis goes through the design features of the manned Mars mission, its power system requirements, their design attributes as well as their design faults. Specific mass is calculated statistically as well as empirically for 1-15MWe systems. Conclusions are presented on each subsystem as well as recommendations for decision makers on where development needs to begin today in order for the mission to launch in the future.

Space Nuclear Propulsion for Human Mars Exploration identifies primary technical and programmatic challenges, merits, and risks for developing and demonstrating space nuclear propulsion technologies of interest to future exploration missions. This report presents key milestones and a top-level development and demonstration roadmap for performance nuclear thermal propulsion and nuclear electric propulsion systems and identifies missions that could be enabled by successful development of each technology.

A brief comparison is made between opposition class (with three impulse return), conjunction class, Venus swing-by to Mars and Mars-Venus double stopover trajectories. Vehicle configurations based on NERVA-I engines of varying life and restart capability are considered. It is found that the opposition and Venus swingby trajectories to Mars yield competitive mission performance; the double stopover entails about 30-percent penalties in initial mass and trip time; and that the minimum-weight vehicle uses a single, restartable engine.

Currently, trade-offs are being made among the various propulsion systems being considered for the Space Exploration Initiative (SEI) missions. It is necessary to investigate the reliability aspects as well as the efficiency, mass savings, and experience characteristics of the various configurations. Reliability is a very important factor for the SEI missions because of the long duration and because problems will be fixed onboard. The propulsion options that were reviewed consist of nuclear thermal propulsion (NTP), nuclear electric propulsion (NEP) and various configurations of each system. There were four configurations developed for comparison with the NTP as baselined in the Synthesis (1991): (1) NEP, (2) hybrid NEP/NTP, (3) hybrid with power beaming, and (4) NTP upper stage on the heavy lift launch vehicle (HLLV). The comparisons were based more or less on a qualitative review of complexity, stress levels and operations for each of the four configurations. Each configuration included a pressurized NEP and an NTP ascent stage propulsion system for the Mars mission.

A new impetus to manned Mars exploration was introduced by President Bush in his Space Exploration Initiative. This has led, in turn, to a renewed interest in high-thrust nuclear thermal rocket propulsion (NTP). The purpose of this report is to give a brief tutorial introduction to NTP and provide a basic understanding of some of the technical issues in the realization of an operational NTP engine. Fundamental physical principles are outlined from which a variety of qualitative advantages of NTP over chemical propulsion systems derive, and quantitative performance comparisons are presented for illustrative Mars missions. Key technologies are described for a representative solid-core heat-exchanger class of engine, based on the extensive development work in the Rover and NERVA nuclear rocket programs (1955 to 1973). The most driving technology, fuel development, is discussed in some detail for these systems. Essential highlights are presented for the 19 full-scale reactor and engine tests performed in these programs. On the basis of these tests, the practicality of graphite-based nuclear rocket engines was established. Finally, several higher-performance advanced concepts are discussed. These have received considerable attention, but have not, as yet, developed enough credibility to receive large-scale development.

Space Nuclear Propulsion and Power: Principles, Systems, and Applications Unlock the Future of Space Exploration Space Nuclear Propulsion and Power: Principles, Systems, and Applications is a vital text for students, practitioners, and industry professionals, offering a deep exploration of space nuclear propulsion and power systems. This extensive guide provides essential knowledge for understanding and advancing technologies that will propel humanity into space. In-depth Coverage of Cutting-Edge Technologies This book examines various propulsion systems, including chemical and nuclear thermal propulsion. It details the fundamentals of rocket propulsion, combustion dynamics, nozzle design, and critical calculations. Readers gain insights into practical considerations, such as high-speed exhaust gas generation and efficiency optimization. Advanced Mathematical Formulations and Real-World Examples To ensure practical application, the book includes real-world examples and detailed mathematical formulations, such as the Tsiolkovsky rocket equation, nuclear fission, radioactivity, and neutronics. These examples help readers understand and apply principles to their studies in space nuclear systems. The structured approach, combining theory with practical examples, makes complex concepts accessible and engaging. Innovative Power Solutions for Space Missions Beyond propulsion, the book explores radioisotope thermoelectric generators (RTGs) and nuclear reactors for powering spacecraft and lunar bases. RTGs, converting heat from radioisotope decay into electricity, have powered missions like Voyager, Cassini, and New Horizons. Nuclear reactors offer high power levels for propulsion and power generation, with detailed coverage of Nuclear Thermal Propulsion (NTP) and Nuclear Electric Propulsion (NEP). NTP systems use a nuclear reactor to heat hydrogen, producing thrust, while NEP systems generate electricity to power electric thrusters, ideal for deep space missions. Powering Lunar Bases and Mars Missions Nuclear technologies extend beyond space travel to lunar and Mars missions. Nuclear reactors provide robust power sources for habitats, scientific experiments, and resource extraction on the Moon and Mars. These environments make solar power less viable, especially for long-duration missions. Nuclear power supports life support systems, communication, and mobility, offering sustainable energy where sunlight is insufficient. Inspiration for Future Innovators Space Nuclear Propulsion and Power is more than a textbook; it challenges readers to think critically about the future of space exploration and the role of nuclear technology. Emphasizing theory and practice integration, the book inspires curiosity and innovation, encouraging contributions to ongoing design and development in this fascinating field. Join the Journey to the Stars Whether you are a student or a seasoned professional, Space Nuclear Propulsion and Power offers valuable insights and guidance. Engage with the material, challenge presented concepts, and join the community advancing technologies that will shape space exploration's future and our understanding of the universe. Embrace the journey into the unknown and unlock the potential of space nuclear propulsion and power with this definitive text. Welcome to an exploration of technologies propelling humanity to the stars.