Pushing the Limits: Thermal and Fluid Challenges in Nuclear Space Propulsion
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Abstract:
Nuclear propulsion systems push thermal and fluid engineering into regimes beyond those encountered in conventional terrestrial and aerospace systems. Nuclear thermal propulsion (NTP) couples nuclear heat generation with hydrogen flow through fuel at temperatures exceeding 2700 K, creating extreme challenges in materials compatibility, heat transfer, fluid stability, transient response, and tightly coupled reactor/propellant control. Nuclear electric propulsion (NEP) presents a different but equally demanding set of challenges, including long-duration operation of high-power systems, radiation-tolerant power and propulsion hardware, high-temperature thermal rejection, and the development of lightweight radiators capable of dissipating substantial waste heat. This presentation will explore the thermal and fluid modeling and analysis challenges underlying both approaches, highlighting the multiphysics interactions, extreme operating environments, and system-level trade spaces that must be understood to enable future nuclear-powered spacecraft. The discussion will also consider where advances in modeling, experimentation, and validation are needed to bridge the gap between component-level understanding and reliable, integrated nuclear propulsion systems.
About the Speaker:
Dr. Kurt Polzin is a senior aerospace engineer and technical leader with more than 20 years of experience in advanced space propulsion, spacecraft systems, and aerospace technology development. He is from the George C. Marshall Space Flight Center and currently serves as NASA’s Capability Manager for Advanced Propulsion within the Space Transportation Program, where he leads technology development activities spanning electric propulsion, green propellants, solar sails, and other advanced propulsion technologies. Previously, he served for five years as Chief Engineer for NASA’s Space Nuclear Propulsion portfolio as the engineering technical authority, leading multidisciplinary teams developing nuclear thermal and nuclear electric propulsion technologies. His technical expertise includes propulsion system design and analysis, plasma and fluid dynamics, thermal systems, spacecraft power, and experimental methods. Dr. Polzin holds a Ph.D. in Mechanical and Aerospace Engineering from Princeton University and is an AIAA Fellow.