Operation and Development Status of the Spacecraft Fire Experiments (Saffire)
Ruff, Gary A., Urban, David L.
Experiments: SAFFIRE I, SAFFIRE II, SAFFIRE III, SAME
Since 2012, a series of Spacecraft Fire Experiments (Saffire) have been under development by the Spacecraft Fire Safety Demonstration (SFS Demo) project, funded by NASA's Advanced Exploration Systems Division. The overall objective of this project is to reduce the uncertainty and risk associated with the design of spacecraft fire safety systems for NASA's exploration missions. The approach to achieving this goal has been to define, develop, and conduct experiments that address gaps in spacecraft fire safety knowledge and capabilities identified by NASA's Fire Safety System Maturation Team. The Spacecraft Fire Experiments (Saffire-I, -II, and -III) are material flammability tests at length scales that are realistic for a spacecraft fire in low-gravity. The specific objectives of these three experiments are to (1) determine how rapidly a large scale fire grows in low-gravity and (2) investigate the low-g flammability limits compared to those obtained in NASA's normal gravity material flammability screening test. The experiments will be conducted in Orbital ATK's Cygnus vehicle after it has unberthed from the International Space Station. The tests will be fully automated with the data downlinked at the conclusion of the test before the Cygnus vehicle reenters the atmosphere. This paper discusses the status of the Saffire-I, II, and III experiments followed by a review of the fire safety technology gaps that are driving the development of objectives for the next series of experiments, Saffire-IV, V, and VI.
Test conditions.
Extracted from the paper by AI · “Verified” means a person checked it
| Fuel | O₂ | Pressure | Airflow | Sensors | Source | AI conf. | Status |
|---|---|---|---|---|---|---|---|
| Composite fabric (75% cotton – 25% fiberglass) 0.4 m wide x 0.95 m long panel |
near 0.21 O2 mole fraction | — | Uniform flow across samples drawn by fans | Ambient temperature sensors (inlet, flame plume, outlet), Oxygen and CO2 concentration sensors (inlet of avionics bay), Pressure transducer, Two flow anemometers, Two video cameras, Thermocouples (woven into sample, bent upward), Radiometer, Fan tachometer | p. 4 | 95% | Pending |
| PMMA (flat and structured), Silicone, Composite fabric, Nomex Nine samples (5 cm x 29 cm) on a card |
— | — | — | Ambient temperature sensors, Oxygen and CO2 concentration sensors, Pressure transducer, Two flow anemometers, Two video cameras, Thermocouples | p. 4 | 90% | Pending |
Findings.
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01
Prior microgravity combustion experiments were limited to sample sizes no larger than 10 cm, whereas serious spacecraft fires could consume an order of magnitude more material.
Other · p. 2 · AI confidence 95% · Reported · Pending
“Prior experiments have been limited to samples no larger than 10 cm in length and width whereas a serious spacecraft fire could consume as much as an order of magnitude more material.”
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02
Saffire experiments are conducted in Orbital ATK’s Cygnus vehicle after it has unberthed from the International Space Station.
Other · p. 1 · AI confidence 95% · Reported · Pending
“The experiments will be conducted in Orbital ATK’s Cygnus vehicle after it has unberthed from the International Space Station.”
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03
The Saffire experiment package includes a flow duct with fans and flow straighteners to provide uniform flow and prevent burning debris from interacting with the rest of the cargo.
Prevention · p. 3 · AI confidence 90% · Reported · Pending
“This duct will provide a uniform flow across the samples, maintain a clear flow path within the experiment module, and prevent burning debris from interacting with the rest of the cargo.”
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04
Saffire-I operations begin after Cygnus separates from ISS and concludes joint operations, with commanding performed by the Orbital ATK Mission Operations Team.
Other · p. 5 · AI confidence 90% · Reported · Pending
“Following separation from ISS and concluded joint operations, Saffire-I operations will begin. All commanding of and communication with the Saffire payload is performed by the Orbital ATK Mission Operations Team (MOPS)”