Fire is one of the most serious concerns for upcoming crewed space missions. Scientists from NASA Glenn Research Center, Johnson Space Center, and Case Western Reserve University have outlined an experiment to study how materials burn on the Moon, where fire is expected to behave differently than on Earth.
On Earth, gravity makes hot gases rise, pulling in cooler oxygen at the base of a flame. This process can sometimes extinguish weaker fires through a phenomenon known as “blowoff.” On the Moon, weaker airflow lets oxygen keep feeding the flame without being disrupted. As a result, materials that barely burn on Earth could sustain flames for much longer on the lunar surface.
Understanding this is crucial, since future lunar habitats cannot risk uncontrolled fires. With plans for a long-term human presence on the Moon approaching, researchers want to identify prevention strategies early.
Limits of Earth-Based Fire Testing for Space Materials
NASA uses the NASA-STD-6001B test, applying a flame to a vertical sample; if it burns past a set point or drops flaming debris, it fails, but because it’s conducted on Earth, it doesn’t fully reflect how materials behave in space, such as on the Moon.
On Earth, moving air creates convection currents, and gravity defines clear “up” and “down” directions. In places like the International Space Station, however, those directional cues don’t exist.
As a result, flames in microgravity don’t rise upward. Instead, they form slow-growing, spherical shapes and rely largely on the station’s ventilation system to supply oxygen.
Shutting down the ventilation system wouldn’t fully fix the issue. While reduced airflow might slow a fire, it could leave materials smoldering, ready to reignite once the fans come back on.
A more effective approach has been to study fire behavior directly aboard the International Space Station. In one series of experiments, researchers ignited around 1,500 small flames to better understand how combustion works in microgravity.
Why NASA Works to Prevent Large Fires in Spacecraft
For obvious safety reasons, NASA aims to avoid large fires that could damage materials or endanger an entire spacecraft. Allowing a significant blaze would put the whole habitable environment at risk.
Instead, the agency has relied on the Spacecraft Fire Safety (Saffire) experiment series. These tests took place inside uncrewed Cygnus cargo spacecraft capsules after they separated from the International Space Station, just before reentering Earth’s atmosphere and burning up.
In these experiments, scientists set fire to large samples of cotton–fiberglass blends, fabric, and acrylic to observe how they behaved in microgravity.
They discovered some unusual effects, such as flames moving against the direction of airflow and burning more intensely on thinner materials.
The Saffire experiment revealed gaps between NASA’s standard tests and how fire behaves in space.
Researchers then turned to another approach—drop testing. Brief weightlessness from drop towers (~5 seconds) or parabolic flights (~25 seconds) is too short to study long-term fire effects.
That led to the Flammability of Materials on the Moon (FM2) experiment, which focuses on studying combustion in the Moon’s lower gravity—an environment that offers unique insights into flame behavior.
FM2 Lunar Fire Experiment on CLPS Mission
FM2 will fly on a Commercial Lunar Payload Services mission to the Moon, where a sealed chamber will ignite four solid fuel samples under sustained lunar gravity that cannot be replicated on Earth. The setup will include cameras, radiometers, and oxygen sensors to track the flames and surrounding conditions in real time.
It will provide the first link between predicted flame behavior in partial gravity and the real-world results observed in both normal Earth gravity (1G) and zero-gravity experiments.
Extended Data Collection Compared to Short-Duration Microgravity Tests
Importantly, the experiment will collect data over several minutes, rather than just the few seconds possible with drop tests and parabolic flights.
NASA may or may not update its standard due to the high cost of lunar testing, but real data is essential. FM2 will, for the first time, directly measure fire behavior on a future lunar outpost. Scientists—and even science fiction writers—are expected to watch the results closely.
Read the original article on: sciencealert
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