Microgravity Research Illuminates Fundamental Combustion Physics During ESA Parabolic Flights

The European Space Agency (ESA) recently concluded its 87th parabolic flight campaign in Bordeaux, France, during September 2025. This intensive research period focused on investigating fundamental physical processes when the influence of gravity is effectively removed. Central to the investigation was a detailed examination of a simple candle flame, a common object on Earth that becomes a complex subject when freed from gravitational constraints, aiming to deepen understanding of combustion mechanics in near-weightless conditions.

Parabolic flights, often referred to as 'Zero-G' maneuvers, involve an aircraft executing a specific trajectory to generate approximately 22 seconds of simulated microgravity per arc. Under normal terrestrial conditions, heat from a flame causes surrounding air to rise, creating convection currents that shape the fire into its familiar teardrop silhouette. When gravity is absent, this buoyant force disappears, fundamentally changing the flame’s structure. Researchers noted that the removal of gravitational influence caused the flame to adopt a more spherical configuration, a direct result of surface tension and diffusion becoming the dominant forces.

Jack van Loon, representing ESA's Life Support and Physical Sciences Laboratory, led this segment of the research. Van Loon stated that decoupling the experiment from gravity's constant pull provides an unmatched chance to isolate and study the interplay of other subtle forces, specifically convection and capillary action within the combustion process. This meticulous work is part of ESA's ongoing scientific inquiry, leveraging microgravity platforms to probe nature's foundational laws. The resulting data is expected to refine understanding of physical principles, offering advancements for fields like fluid dynamics and the engineering of more efficient combustion systems.

Related aerospace research underscores the critical nature of these findings for extended space missions. Studies conducted aboard the International Space Station (ISS) have previously indicated that flame behavior in microgravity is significantly influenced by wick material and fuel composition. Some ISS experiments revealed that flames could extinguish prematurely if oxygen supply was not carefully managed, due to the lack of buoyant airflow for replenishment. This highlights that while the shape changes, the underlying requirement for efficient reactant mixing remains crucial for any sustained burning. The next parabolic flight campaign is already scheduled for November 2025, ensuring a continuous stream of novel data for the scientific community.