Smoke emission and temperature characteristics of the long-term overloaded wire in space

We developed an experimental payload to study the overloaded characteristics of wire insulations on board the China’s SJ-10 satellite. In 2-week microgravity experiments provided by the orbital flight, the smoke emissions of overloaded wire insulations were observed in space for the first time. Two smoke emission modes, namely the end smoke jet and the bubbling smoke jet, were identified with polyethylene insulations. The results showed that the geometry of the pyrolysis front dominated the direction and the range of the end smoke jet. The non-oxidative pyrolysis that occurred between the wire core and the insulation produced the high-temperature smoke and caused the bubbling smoke jet. The bubbling jet has a significant impact on the temperatures of adjacent wires, revealing an additional fire risk in microgravity. The effects of insulation thickness and excess current on the temperature rise were also discussed.