This is the Alpha Magnetic Spectrometer (AMS-02) instrument. It is a large cosmic ray experiment for the International Space Station. It sits on the outside of the station, looking out into space. High-energy particles pass through AMS, interacting with different detectors on the way. Each detector contributes a bit of information about the particle; by combining all of the information, we can identify the particles, and hopefully learn where they come from.
Click on the links, or the picture, to learn how the different subsystems work! You can learn about the six particle detection systems, and several of the important support systems.