The number one priority for any mission is safety. Fire is a significant threat to crewed missions, and understanding how fire behaves in microgravity is critical. So too is the ability to develop operational best practices for mitigating fire emergencies, especially when astronauts aren’t able to quickly return to Earth or evacuate the spacecraft.
NASA’s Space Fire Safety Demonstration Project SAFFIRE (Spacecraft Fire Experiment) enables astronauts to conduct small-scale fire experiments during missions, investigating flame growth and flammability of different materials in space. These experiments are ignited in a Cygnus cargo vehicle before its planned (and destructive) reentry into Earth’s atmosphere.
Managed by NASA’s Advanced Exploration Systems Division, SAFFIRE is an impressive example of the division’s goal: pioneering innovative, public-private partnerships to develop systems, advance capabilities and validate concepts for future crewed exploration missions. The first SAFFIRE launched in March of 2016 and the series of SAFFIRE experiments continue today.
Voyager’s Saffire Flow Unit (SFU) has been an integral part of IV, V and VI flight experiments. To verify SFU fan performance and flow uniformity at reduced atmospheric pressure, we took our SFU as high as we could – up to 14,000 feet atop Pikes Peak, outside of Colorado Springs, Colo.
Voyager expanded the science data return on SAFFIRE IV, V and VI by adding six remote sensors to measure transport of combustion by-products (CO2 and temperature) and a Far-Field Diagnostics (FFD) package measuring smoke particles and providing a fire clean-up technology demonstrator. The SFU was redesigned to measure inlet and outlet gas concentration to provide the science team with heat release rates (flame calorimetry). We also added two more cameras for flame visualization, helping to obtain planar and edge views of fire growth and dynamics.
SAFFIRE IV, V and VI carried two large tanks of 100% oxygen to allow for the atmospheric condition within the Cygnus capsule to be adjusted for possible future longer duration missions. This created an environment – simulating the real-life conditions astronauts would experience during NASA’s upcoming Artemis missions to the Moon – during the sample burns that had not previously been studied in microgravity.
Acid gasses (hydrochloric or hydrofluoric) were carried by the SFU as well. These gasses can be combustion byproducts of some materials, and by carrying this gas and releasing it at specific points in the experiment run, data was obtained regarding the transport and detection of the acid gasses within a spacecraft.
During the experiment, several samples were ignited inside the Cygnus cargo spacecraft, with the elevated oxygen levels showing more energetic flames than in previous experiments. With the support of Voyager’s team, NASA is not only able to investigate flame growth and material flammability in space through its SAFFIRE programs, but also glean valuable insights to support bigger science end products, including fire behavior, flame growth/dynamics, modeling, post-fire monitoring and clean up.
*The legacy of this hardware is with ZIN Technologies, which Voyager Space acquired in March 2023.