The Fiery Conclusion of NASA’s Saffire Experiment Ignites New Possibilities

The Saffire experiment series, led by NASAEstablished in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. Its vision is "To discover and expand knowledge for the benefit of humanity." Its core values are "safety, integrity, teamwork, excellence, and inclusion." NASA conducts research, develops technology and launches missions to explore and study Earth, the solar system, and the universe beyond. It also works to advance the state of knowledge in a wide range of scientific fields, including Earth and space science, planetary science, astrophysics, and heliophysics, and it collaborates with private companies and international partners to achieve its goals.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>NASA’s Glenn Research Center, concluded with its final mission, Saffire-VI. It investigated fire behavior in space to improve safety and design for future spacecraft. The experiments provided valuable data for safer deep-space exploration.

NASA recently concluded the final mission of its Spacecraft Fire Safety Experiment, or Saffire, putting a blazing end to an eight-year series of investigations that provided insights into fire’s behavior in space.

The final experiment, Saffire-VI, launched to the International Space StationThe International Space Station (ISS) is a large spacecraft in orbit around the Earth that serves as a research laboratory and spaceport for international collaboration in space exploration. It was launched in 1998 and has been continuously occupied by rotating crews of astronauts and cosmonauts from around the world since 2000. The ISS is a joint project of five space agencies: NASA (USA), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). It orbits the Earth at an altitude of approximately 400 kilometers (250 miles), and provides a unique platform for scientific research, technological development, and human space exploration.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>International Space Station in August 2023 and concluded its mission on January 9, when the Northrop Grumman Cygnus spacecraft it was flying on safely burned up during planned re-entry into Earth’s atmosphere.

Dr. David Urban, principal investigator, and Dr. Gary Ruff, project manager at NASA’s Glenn Research Center in Cleveland, have led the Saffire project from Northeast Ohio since its initial spark in 2016. Throughout the experiment series, researchers gathered data NASA will use to enhance mission safety and inform future spacecraft and spacesuit designs.

A sample of fabric burns inside an uncrewed Cygnus cargo craft during a previous Spacecraft Fire Safety Experiment investigation, Saffire-IV. Credit: NASA

“How big a fire does it take for things to get bad for a crew?” Urban said. “This kind of work is done for every other inhabited structure here on Earth – buildings, planes, trains, automobiles, mines, submarines, ships – but we hadn’t done this research for spacecraft until Saffire.”

Like previous Saffire experiments, Saffire-VI took place inside a unit on an uninhabited Cygnus spacecraft that had already departed from the space station, ensuring the safety of the orbiting laboratory and a more representative flight environment. However, this final iteration of the experiment was unique because of the higher oxygen concentration and lower pressure generated in the test unit to simulate the conditions within crewed spacecraft.

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NASA ignited the final set of space fire experiments for Saffire-VI inside Northrop Grumman’s Cygnus cargo spacecraft at the end of the NG-19 resupply mission to the International Space Station. Saffire, or Spacecraft Fire Safety Experiment, was a series of six investigations that provided insights into how fires grow and spread in space. This research is especially important as it will inform future spacecraft designs bound for the Moon and MarsMars is the second smallest planet in our solar system and the fourth planet from the sun. It is a dusty, cold, desert world with a very thin atmosphere. Iron oxide is prevalent in Mars' surface resulting in its reddish color and its nickname "The Red Planet." Mars' name comes from the Roman god of war.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>Mars. Credit: NASA

During the 19 Saffire-VI experiment runs, the NASA team and counterparts at Northrop Grumman made various adjustments to air conditions. They then ignited a flame on materials such as plexiglass, cotton, Nomex, and Solid Inflammability Boundary at Low-Speed fabrics. A bead-lined wire inside the unit ignited the materials.

“The Saffire flow unit is a wind tunnel. We’re pushing air through it,” Ruff said. “Once test conditions are set, we run electrical current through a thin wire, and the materials ignite.”

Cameras inside allowed the team to observe the flame while remote sensors outside the Saffire flow unit collected data about what was happening in the Cygnus vehicle. The images and information were gathered in real-time before being sent to Earth for scientists to analyze.

“You’ve got a heat release rate and a rate of release of combustion products,” Ruff said. “You can take those as model input and predict what will happen in a vehicle.”

The next decade of exploration and science missions will see astronauts flying deeper into space and to locations that have yet to be explored. Though the Saffire experiments have been extinguished, NASA has learned valuable lessons and gathered mountains of data on fire behavior that will help the agency design safer spacecraft and accomplish its ambitious future missions.