Fire Prevention, Detection and Suppression / Advanced Capabilities Project Office

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Glenn Leads Spacecraft Fire Safety Tech Development Effort

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Space travel poses many risks for astronauts since they are confined to the spacecraft during both normal and emergency operation. They must be able to quickly react to hazardous situations while maintaining their health and safety. Fire is especially dangerous inside a spacecraft or planetary habitat because it can be difficult to detect and extinguish a fire in microgravity.

To maintain astronaut safety during increasingly difficult exploration missions, NASA’s Glenn Research Center is leading technology development for spacecraft fire safety through the Fire Prevention, Detection and Suppression Project. Glenn’s extensive background in microgravity research and support from universities is helping to improve fire safety for the Orion crew exploration vehicle.

Prevention

Image: Allied Signal/Honeywell light-scattering smoke detector used in the ISS.

To prevent fires from occurring, the flammability of materials inside the spacecraft must be tested at the oxygen levels and atmospheric pressure in which they will be used. These tests indicate the flammability on Earth, but they do not reveal how the material will burn in low gravity. As new lightweight materials for exploration missions are developed, they will also need to be analyzed for flammability.

To improve the methods to assess material flammability and fire prevention, Glenn will accomplish the following:

Develop tests that can be performed on Earth to analyze the flammability of materials in low gravity
Assess material flammability in exploration vehicles and habitats in low and partial gravity

Detection

Image: Portable CO2 fire extinguisher used on the U.S. modules of the ISS.

If a fire starts in space, it is vital that the astronauts detect it immediately. The smoke detectors used on the International Space Station and Space Shuttle are generally not desirable for use on future exploration missions. Standard smoke detectors are designed to detect smoke particles that form on Earth. Experiments conducted in microgravity have shown that the particle size formed in low gravity is larger than those produced on Earth.

Additionally, smoke detectors on Shuttle and Station have been susceptible to false alarms from the dust particles. Every false alarm must be investigated by the crew, which wastes valuable time and decreases their confidence in the fire detection system. When pre-fire events have occurred in space, the crew usually detects the situation with their noses before the detectors notify them.

To solve the above problems, Glenn is creating advanced detection systems that combine particle and gas-sensing capabilities that respond quickly to fires and better differentiate between a signal from a fire and one from another source. Glenn is also developing a data bank of fire signatures (signals that trigger the sensor to respond to a fire) that will also help the new detectors reduce false alarms.

Suppression

Image: A burning sample in the Upward Flame Propagation test (Test 1).

Once a fire is detected, the astronauts must act fast to put it out. In the Space Shuttle, the crew can use a Halon fire extinguisher. In the Space Station, a portable CO2 extinguisher can be used in the U.S. modules while the Russian side has a water-based foam device.

The requirements for fire extinguishers for Orion require a re-evaluation of fire suppression technologies. Compared to the Space Station, Orion is very small. If Orion’s crew used a CO2 extinguisher, it would dilute the oxygen level inside the vehicle so much that the atmosphere would become hazardous to their health. The use of Halon is not desired because it cannot be removed from the cabin atmosphere and it can produce harmful products when it interacts with the fire. Foam extinguishers may be suitable, but would be more difficult to clean-up.

Glenn is currently working to establish the unique requirements for new fire extinguishers for Orion. Glenn is also testing various types of suppressants and evaluating how they will be dispersed in low gravity.

Fire safety is a key issue for future exploration missions. Glenn’s current efforts in leading the Fire Prevention, Detection and Suppression Project will help ensure the health and safety of the astronauts.

Contact at NASA Glenn Research Center
Chief, Advanced Capabilities Project Office: Ann P. Over
Space Flight Systems Directorate / Advanced Flight Projects Office
216-433-6535