Lunar Combustion Investigation: Flammability Results from a Rotating Sounding Rocket

The Lunar Combustion Investigation (LUCI) demonstrates the feasibility of conducting material flammability experiments in partial-g. A spinning Blue Origin New Shepard sounding rocket yields Lunar gravity by using centrifugal acceleration. These are the first-ever, extended-duration (greater than 25 seconds) combustion tests performed in simulated Lunar gravity. A steady vehicle rotation of 11 RPM is established, with an effective radius of rotation of 1.22 m at the experiment location. Two samples are burned simultaneously in air at normal pressure. The first sample is a cotton-fiberglass composite fabric sheet and the second a 4-mm diameter rod of acrylic plastic (polymethyl methacrylate). Flame images from two orthogonal cameras are used to determine flame spread and growth rates, and the burn lasts for over two and a half minutes. The oxygen concentration in the chamber is measured. As the burns progress, the oxygen concentration drops, enabling a limiting value for extinction to be defined. The effect of Coriolis force is discussed. Results from this experiment are compared to related 1-g work, drop tower tests, aircraft experiments, and modeling. The results are applicable to NASA’s exploration efforts in that they guide the selection of fire-safe materials and environments and ensure safety of future spacecraft and Lunar habitats. The data also provides fundamental understanding of fires. Finally, the experiment is a steppingstone to the ultimate goal of performing burn tests on the Lunar surface in the Flammability of Materials on the Moon (FM2) experiment which is planned to launch in late 2026.