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Risk to Crew Health Due Electrical Shock

The space shuttle Endeavour is seen on launch pad 39 with lightning in the background
The space shuttle Endeavour is seen on launch pad 39a as a storm passes by prior to the rollback of the Rotating Service Structure (RSS), Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank and additional spare parts for Dextre. Launch is targeted for Friday, April 29 at 3:47 p.m. EDT.

It is important to protect humans from unintended electrical current flow during spaceflight. The thresholds for contact electrical shock are well established, and standards and requirements exist that minimize the probability of contact electrical shock. Current thresholds were chosen (vs. voltage thresholds) because body impedance varies depending on conditions such as wet/dry, AC/DC, voltage level, large/small contact area, but current thresholds and physiological effects do not change. By addressing electrical thresholds, engineering teams are able to provide the appropriate hazard controls, usually through additional isolation (beyond the body’s impedance), current limiters, and/or modifying the voltage levels. Risk assessment determined that the probability of an event was extremely low, and the most serious consequence is expected to be involuntary muscle contraction.

Lightning strikes the Launch Pad 39B protection system
Lightning strikes the Launch Pad 39B protection system as preparations for launch of NASA’s Space Launch System (SLS) rocket with the Orion spacecraft aboard continue, Saturday, Aug. 27, 2022, at NASA’s Kennedy Space Center in Florida. NASA’s Artemis I flight test is the first integrated test of the agency’s deep space exploration systems: the Orion spacecraft, SLS rocket, and supporting ground systems. Launch of the uncrewed flight test is targeted for no earlier than Aug. 29 at 8:33 a.m. ET. Photo Credit: (NASA/Bill Ingalls)

Directed Acyclic Graph Files

+ DAG File Information (HSRB Home Page)

+ Electrical Shock Risk DAG and Narrative (PDF)

+ Electrical Shock Risk DAG Code (TXT)



Last Updated
Sep 26, 2023
Robert E. Lewis