The real goal of the seismic experiments was to figure out the Moon's internal structure. Measuring how long the reverberations last, how powerful they are, and how big the waves get can reveal what the Moon is made of. Remote seismic stations were instrumental in this investigation, and they were deployed as part of the Apollo Lunar Surface Experiment Packages that astronauts set up on the Moon on Apollos 12, 14, 15, and 16; different versions were deployed on Apollos 11 and 17. From when they were first set up to when they were remotely shut down in 1977, these ALSEPs recorded all kinds of seismic activity. The data was sent back to receiving stations on Earth where the signal was magnified by 10 million so scientists could interpret the signal.