The samples were all collected during the Apollo 15, 16, and 17 missions. None of them have ever been exposed to Earth’s atmosphere, but they’ve been preserved in very different ways. For example, one Apollo 17 sample, returned to Earth in 1972, is 1.8 pounds of a vacuum-sealed lunar core that contains a stratified layer of rock, and will be studied by six of the nine chosen research teams. Meanwhile, another team will have access to an Apollo 15 sample that’s been stored in helium since 1971. Some samples from the missions have been kept frozen since they were brought back to Earth, while others have remained sealed in room-temperature storage.