Pyrotechnics

Location of Apollo pyrotechnics devices

The Pyrotechnics (or 'Pyros' for short) are small explosive devices used for many purposes on the Apollo spacecraft.

Operation

Typically a pyro consists of a small wire in an explosive charge which is heated until the explosive detonates: this might then explode a nut which is used to bolt two stages together, or fire a guillotine which cuts electrical cables connecting two stages. It is essential that these function reliably, as a failure to separate properly could be extremely hazardous to the crew, if not fatal.

The CSM pyros are detonated by special pyro batteries, which are not connected to the main buses and are not rechargeable. Currently some of the pyros are fully simulated and require a fraction of a second of power to detonate, while others simply explode instantly; eventually the simulation will be extended to correctly handle all pyros.

Switches

Location of pyro arming switches

The main spacecraft pyros are armed by two switches on Panel 8 on the left-hand side of the CM (A and B). Most will not function if the switches are not activated.

External Links

• Apollo Experience Report: Spacecraft Pyrotechnic Systems
• Apollo Operations Handbook: Sequential Systems

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