Materials International Space Station Experiment

The Materials International Space Station Experiment (MISSE) is a series of experiments mounted externally on the International Space Station (ISS) that investigates the effects of long-term exposure of materials to the harsh space environment. The MISSE project evaluates the performance, stability, and long-term survivability of materials and components planned for use by NASA, commercial companies and the Department of Defense (DOD) on future low Earth orbit (LEO), synchronous orbit and interplanetary space missions.

Source: Wikipedia — Materials International Space Station Experiment (CC BY-SA 4.0)