IEH (International Extreme Ultraviolet Hitchhiker) was a package of experiments to study sources of high-energy ultraviolet radiation, including the Sun, hot stars, and more remote objects, and the interaction of solar ultraviolet with Earth's upper atmosphere. IEH was carried inside the Space Shuttle's payload bay, deployed in orbit, and then returned to Earth at the end of the Shuttle's mission. It was flown several times in a variety of configurations.