NASA plans first-ever lunar fire test to ensure astronaut safety.

NASA is preparing to ignite a controlled fire on the lunar surface, a bold move designed to uncover the hidden dangers that could plague future space missions. While the vacuum of space presents many threats, fire stands out as one of the most frightening risks for astronauts. The behavior of flames changes drastically in low-gravity environments like the moon or the International Space Station compared to Earth. Materials that are safe from burning here might sustain combustion for extended periods out there, turning a minor spark into a prolonged hazard.

To address this, NASA researchers have proposed the first-ever flammability test on the moon, with a launch scheduled for later this year. Four specific fuel samples will be loaded into a sealed chamber and transported to the lunar surface as part of an uncrewed Commercial Lunar Payload Service (CLPS) mission. Once there, these materials will be ignited while cameras and sensors track the flame's spread and measure its oxygen consumption.

These experiments are critical as NASA readies for the Artemis IV mission, which aims to return humans to the moon in 2028. Scientists emphasize that understanding how fires behave in such unique conditions is essential for ensuring the safety of future crews. The ultimate goal is to simulate a disaster scenario during a lunar landing, providing the data needed to prevent a small ignition from becoming a catastrophic event.

On Earth, fire behavior is dictated by gravity and air currents, which cause hot, less-dense air to rise and draw cool, oxygen-rich air into the base of a flame. This convection process can sometimes trigger a "blowoff," where the resulting air current extinguishes a weak fire. In contrast, the Moon's gravity is only one-sixth that of Earth, slowing this process significantly. This allows oxygen flow to sustain a small flame without extinguishing it, creating conditions where the Moon's gravity may actually represent a near-perfect environment for igniting fires with minimal oxygen. Since lunar habitats will operate at oxygen pressures similar to Earth's, the risk of fire on a lunar outpost or lander is a genuine and serious danger.

To address this, scientists are preparing to launch a combustion chamber to the Moon later this year to observe how materials burn under lunar gravity. This investigation is critical because materials can be more flammable in space, yet NASA currently has limited methods to test this on Earth. Dr. Paul Ferkul of NASA's Glenn Research Center and his co-authors note in their research that early evidence suggests lunar gravity could be more hazardous than microgravity or Earth gravity. "Early numerical and experimental evidence suggested that Lunar gravity could be more hazardous, since flame spread rate as a function of gravity peaks there," they state. "Consequently, partial-g fire in an extraterrestrial habitat is a real hazard that is expected to be substantially worse than in 0-g and potentially worse than even 1-g." This finding underscores NASA's urgent need to understand fire dynamics before sending humans back to the Moon in 2028.

A major obstacle for NASA's fire safety program is the difficulty of replicating fire spread in microgravity on Earth. The agency currently relies on NASA-STD-6001B, a test where a six-inch flame is applied to the bottom of a material; if the fire burns more than six inches upward or drips burning debris, the material fails. However, this test fails to capture the realities of space fire. Without gravity, fire does not point upward; instead, it grows into spherical blobs that spread slowly outward. While astronauts on the International Space Station (ISS) have ignited approximately 1,500 tiny fires in the Combustion Integrated Rack, these are strictly limited in size for safety.

The most effective test to date has been the Spacecraft Fire Safety (Saffire) program, which ignited sheets of cotton, fiberglass, and acrylic inside an uncrewed Cygnus cargo capsule before it re-entered Earth's atmosphere. Attempts to replicate these conditions on Earth using drop towers or parabolic flights can only simulate microgravity for a few minutes. The Saffire tests revealed unexpected physics, such as flames spreading against the direction of airflow and burning hotter on thinner materials. These unusual results convinced NASA scientists that they required a clearer picture of potential fire scenarios for lunar missions. When the Flammability of Materials on the Moon (FM) test launches later this year, it will mark the first time NASA can observe a large fire in space and the first time anyone will light a fire on the lunar surface.