Huntsville Alabama L5 Society (HAL5)
Space Advocacy | Education Outreach | Technology Development

Nuclear Rocket Engines (NRE) for in-space propulsion has been an interest of space agencies, since first conceived back in the late 1950's. In the 1960's, besides working on Apollo to get men to land on and roam the Moon, the United States also had a major space nuclear program that involved designing, building, and testing nuclear rocket engines. That ROVER/NERVA program was terminated in 1972, but nuclear propulsion been seriously revisited with programs such as the Space Exploration Initiative in the early 1990's and most recently with the NASA Game Changing Development Nuclear Thermal Propulsion (NTP) project to support Human crewed missions to Mars. The latest efforts include pursuing the use of low enriched uranium fuel instead of the high enriched used in the earlier reactors.

The fundamentals of NTP include: 1) Propellant is heated by a nuclear reactor and thermally expanded through a nozzle; 2) Low molecular weight, mono-propellant gas, hydrogen, allows one to raise the Specific Impulse (Isp) and simplify the tankage needed for storing the liquefied gas; 3) Specific impulse can be about twice that of chemical liquid rocket engines - related to reactor exhaust temperature and inversely to molecular weight of propellant gas; 4) The thermal power of reactor is directly related to thrust via the Isp which determine the propellant mass flow rate and the enthalpy rise; 5) The amount of uranium fissioned for round trip mission to Mars is <100 gm in three 500 MWt reactors.

Dr. Witter will provide an overview of the fundamentals of operations, the challenges faced with using low enriched fuel, some of the fun differences in engineering attitude when rocket engineers and nuclear engineers get together, and the benefits that can be realized for various exploration missions if a nuclear rocket engine is used.

The event is free and open to the public.

About Dr. Jonathan Witter, Ph.D.

Jonathan Witter is the Chief Engineer for BWXT's Advance Technology Programs. In this role, he currently serves as the technical engineering lead for the NASA GCD Nuclear Thermal Propulsion (NTP) project with a focus on the reactor core design and analysis and the fuel mechanical development and testing. Dr. Witter has past experience with space nuclear programs where he served as a reactor physics design lead for the Project Prometheus/Jupiter Icy Moon Orbiter fission power system in the early 2000's while working at the Knolls Atomic Power Laboratory and did his PhD work at Massachusetts Institute of Technology under a NASA Space Grant working on nuclear thermal propulsion under the Space Exploration Initiative in the early 1990's. Between stints in space nuclear applications, Jonathan worked in both the naval and commercial nuclear industry gaining experience in the operations and design of reactor systems and with the testing to advance and validate conceptual designs.