Fire is extremely dangerous on a spacecraft, so most controlled flame growth experiments have been limited to small sizes. The Spacecraft Fire Experiment-I (Saffire-I) intentionally lights a large-scale fire inside an empty Cygnus resupply vehicle after it leaves the International Space Station (ISS) and before it re-enters Earth's atmosphere. Instruments measure flame growth, oxygen use and more, improving understanding of fire growth in microgravity and safeguarding future space missions.