HE overriding goal of advanced space propulsion is to reduce the costs of doing space missions, and to enable totally new types of missions that basically could not be performed (even at essentially unlimited cost) with existing technology. For example, with Earth-launch costs on the order of $10,000 per kilogram (comparable to the current cost of gold!) of delivered payload, one important application of advanced propulsion is to reduce thecostofaccessto space(andtransportation oncein space), both in the initial Earth-launch vehicle and then in the in-space vehicles, by reducing the total mass (most of which is propellant) that must be launched from Earth. This can be achieved by either developing more efe cient, higher-performance (i.e., higher specie c impulse Isp/ propulsion technologies, or by reducing the propellant requirements by reducing dry mass, mission velocity 1V, and so on. (Note however that launch cost is strongly driven by launch frequency; 1 thus, some advanced propulsion concepts attempt to both improve performance and increase launch rate.) A second goal of advanced propulsion is the ability to perform previously “ impossible” missions. An example of an impossible mission is attempting an interstellar mission using chemical propulsion. No matter how large the rocket, no matter how many stages it has, you simply cannot achieve the speeds (typically at least 10%of the speed of light) required for a practical interstellar mission using a chemical propulsion system. More generally, it is not practical to performaspace mission wherethe mission 1V isgreater than afew (e.g., two to three) times the propulsion system’ s exhaust velocity Vexhaust or, equivalently, Isp. Ultimately,theperformanceofanyrocketislimitedbytheRocket

Advanced Space Propulsion for the 21st Century

Soon after demonstration of the first laser, the idea was brought forward to use nuclear energy for excitation of lasers. For pre-1970 reference literature see Ref. 1. This was in the early sixties and, at that time, no commercial size power reactors were in operation. Yet proposals to extract energy out of reactors in the form of light instead of heat were brought forward (1–14). This looks like a bad anachronism, especially considering the difficulties that beset nuclear power today. However, one has to remember that the attitudes of the sixties led to the golden years of research. At that time, one was convinced that the advance of technology could solve most problems for society, and it was only natural that one wanted to cover all opportunities.

Nuclear-Pumped Lasers

Rocket propulsion driven by either thermonuclear fusion or antiproton annihilation reactions is an attractive concept because of the large amount of energy released from a small amount of fuel. Charged particles produced in both reactions can be manipulated electromagnetically making high thrust/high specific impulse (7sp) operation possible. A comparison of the physics, engineering, and costs issues involved in using these advanced nuclear fuels is presented. Because of the unstable nature of the antiproton-proton (pp) reaction products, annihilation energy must be converted to propulsive energy quickly. Antimatter thermal rockets based on solid and liquid fission core engine designs offer the potential for high thrust (~10 Ibf)/ high 7sp (up to -2000 s) operation and 6 month round trip missions to Mars. The coupling of annihilation energy into a high-temperature gaseous or plasma working fluid appears more difficult, however, and requires the use of heavily shielded superconducting coils and space radiators for dissipating unused gamma ray power. By contrast, low-neutron-producing advanced fusion fuels (Cat-DD or DHe) produce mainly stable hydrogen and helium reaction products which thermalize quickly in the bulk plasma. The energetic plasma can be exhausted directly at high 7sp (. 10s) or mixed with additional hydrogen for thrust augmentation. Magnetic ftision rockets with specific powers (ocp) in the range of 2.5 to 10 kW/kg and 7sp in the range of 20,000-50,000 s could enable round trip missions to Jupiter in less than a year. Inertial fusion rockets with ocp > 100 kW/kg and 7sp > 10s could perform round trip missions to Pluto in less than 2 years. On the basis of preliminary fuel cost and mission analyses, fusion systems appear to outperform the antimatter engines for difficult interplanetary missions. *Senior Research Scientist, Advanced Nuclear Propulsion; currently, NASA Lewis Research Center, Cleveland, Ohio; Senior Member of AIAA. Copyright ©1987 by Aerojet TechSystcms Co. Published by the American Institute of Aeronautics Astronautics, Inc. with permission. 89 Purchased from American Institute of Aeronautics and Astronautics

A comparison of fusion/antiproton propulsion systems for interplanetary travel

Principles of Fusion Energy Utilization in Space Propulsion High-Performance Fusion Rocket for Manned Space Missions An Antiproton Catalyzed Inertial Fusion Propulsion System Comparison of Fusion/Antiproton Propulsion Systems for Interplanetary Travel An Antiproton Driver for Internal Confinement Fusion Propulsion From SSTO to Saturn's Moons - Superperformance Fusion Propulsion for Practical Spaceflight Innovative Technology for an Inertial Electrostatic Confinement (IEC) Fusion Propulsion Unit Fusion Plasma Thruster Using a Dense Plasma Focus Device Performance of Fusion-Fission Hybrid Nuclear Rocket Engine Magnetic Control of Fission Plasmas The Outer Solar System and the Human Future.

Fusion energy in space propulsion

NASA LeRC was selected to lead nuclear propulsion technology development for NASA Also participating in the project are NASA MSFC and JPL The US Department of Energy will develop nuclear technology and will conduct nuclear component, subsystem, and system testing at appropriate DOE test facilities NASA program management is the responsibility of NASA/RP The project includes both nuclear electric propulsion (NEP) and nuclear thermal propulsion (NTP) technology development This report summarizes the efforts of an interagency panel that evaluated NTP technology in 1991 Other panels were also at work in 1991 on other aspects of nuclear propulsion, and the six panels worked closely together The charters for the other panels and some of their results are also discussed Important collaborative efforts with other panels are highlighted The interagency (NASA/DOE/DOD) NTP Technology Panel worked in 1991 to evaluate nuclear thermal propulsion concepts on a consistent basis Additionally, the panel worked to continue technology development project planning for a joint project in nuclear propulsion for the Space Exploration Initiative (SEI) Five meetings of the panel were held in 1991 to continue the planning for technology development of nuclear thermal propulsion systems The state-of-the-art of the NTP technologies was reviewed in some detail The major technologies identified were as follows: fuels, coatings, and other reactor technologies; materials; instrumentation, controls, health monitoring and management, and associated technologies; nozzles; and feed system technology, including turbopump assemblies

/pdf/nuclear-thermal-propulsion-technology-results-of-an-4jqqsghm40.pdf

Nuclear thermal propulsion technology: Results of an interagency panel in FY 1991

Open cycle gas core nuclear rocket engine, considering reactor critical experiments and cold and hot flow tests

https://ntrs.nasa.gov/api/citations/19710014431/downloads/19710014431.pdf

Gas-core rocket reactors - A new look

/pdf/gas-core-rocket-reactors-a-new-look-1vwdm41q9a.pdf

E. A. Willis

Papers

Gas-core rocket reactors - A new look

Gas-core rocket reactors - A new look