Jhonathan Rosales, Ph.D.
Nuclear Fuels Lead
Marshall Space Flight Center, NASA
Dr. Jhonathan Rosales serves as the Nuclear Fuels Lead at NASA’s Marshall Space Flight Center. Supports the design and development of nuclear fuels for space nuclear propulsion. SNP systems intend to be far more efficient than chemical rockets. They offer greater flexibility for deep space missions by reducing travel times, limiting the crew’s exposure to cosmic radiation and allowing astronauts to abort missions for a safe return to Earth. NASA intends to employ the NTP concept for missions to Mars and detailed exploration of the solar system.
Prior to joining NASA, he was a graduate research fellow at the Idaho National Laboratory supporting different research projects including the Transient Test Reactor (TREAT) fuel conversion program, the High-Temperature Gas Reactor (HTGR) fuel development program, and the Additive Manufacturing as an Alternate Fabrication Technique (AMAFT) for uranium silicide (U3Si2).
He earned his B.Sc. in mathematics and physics. Then he received Masters and Ph.D. degrees from the University of Florida. His research interests include space nuclear propulsion, nuclear systems, and nuclear fuels for light water reactors. Fabrication technologies including Spark Plasma Sintering (SPS) and laser additive manufacturing.
Space nuclear propulsion offers significant advantages when compared to conventional chemical propulsion concepts. It includes a higher specific impulse (Isp), which brings a higher thrust to weight ratio, shorter travel times, reducing astronauts’ deployment periods, and also incorporates the option for mission abort.
Ceramic-metallic (cermet) nuclear fuel is a promising concept for use in space nuclear propulsion applications due to enhanced thermophysical properties, high-temperature stability and high thermal conductivity.
Cermet nuclear fuels are fabricated by means of spark plasma sintering (SPS). SPS fabrication has demonstrated to be a viable alternative to traditional sintering methods, producing high densities at lower temperatures with rapid processing times.
Cermet fuel undergoes high-temperature testing under H2 environments at different testing sites at NASA – Marshall Space Flight Center. Additionally, this fuel concept is currently being tested under neutron irradiation at the TREAT reactor in Idaho National Laboratory. The results from testing campaigns feed our computational models, enhance our understanding of the fuel performance, and aid in developing the concept to ultimately incorporate it in a nuclear thermal rocket to support NASA’s deep space missions.
Materials Science & Engineering Dept.