Advancing Pool Boiling Bubble Growth and Detachment for Extraterrestrial Applications Through Parabolic Flight Testing

To enable sustained human operations on the Moon and Mars, a deeper understanding of two-phase fluid behavior in reduced gravity is essential, particularly bubble dynamics during nucleate boiling. A parabolic flight campaign was conducted to investigate bubble growth and detachment under Lunar (1/6 g) and Martian (1/3 g) gravities. Heated stainless-steel coupons with varied surface treatments—polished, roughened, structured, and coated—were submerged in FLUTEC-PP1 to induce and observe nucleate boiling. High-speed imaging combined with machine learning-based image analysis showed that reduced gravity significantly increased bubble size, with bubbles in Lunar and Martian gravities reaching approximately 2× and 1.5× the size of those in Earth gravity, respectively. Surface morphology was found to influence bubble mobility, bubble detachment diameter, and total gas generation. These findings underscore the importance of surface design optimization, not only in thermal management systems but also in non-thermal technologies, such as electrochemical reactors, where efficient bubble removal and surface wetting is critical to performance.