Corrosion of Extravehicular Mobility Unit (EMU) Space Suit Assembly (SSA) Components

The SSA (Space Suit Assembly) contains a system of load-bearing rotary bearings, brackets, and attachment rings that provide mobility, sizing adjustments, and secure the fabric softgoods between mobility components such as the lower and upper arm. These critical metallic components, generalized as “hardware,” impact the structural integrity and mobility of the Extravehicular Mobility Unit (EMU). Consequently, hardware is designed to meet stringent corrosion resistance and factor of safety requirements. With a certified operational life of 40 years, metals have the longest life of any material class in the SSA and are the oldest parts of the SSA still in use for Extravehicular Activities. In 2022, surface corrosion was found on three different 17-4 PH stainless steel flight components, a bracket and two different bearings. An extensive failure investigation revealed multiple potential sources of chlorides, which are known to cause corrosion. This paper will discuss EMU metallic components and risk of corrosion, failure investigation methods, and results. Conclusions are drawn for future space suits used in exploration missions.