Ep. 18, Page 73

smbhax on Nov. 21, 2012

Since Selenis is placing them on this asteroid, maybe now is a good time to talk about seismometers! They measure ground motion, and are often used to detect earthquakes. But they can also be used to find out things about the interior of large bodies, because seismic waves will take different paths through a thing, like a planet, depending on what kinds of layers of sediments and rock and so forth they hit along the way. Seismometers were even deployed by astronauts on the Moon during the Apollo missions to find out about the Moon's interior–they also discovered moonquakes, which are small tremors caused by the tidal force of the Earth on the Moon's crust.
Buzz Aldrin deployed the very first seismometer on the Moon during the Apollo 11 mission in 1969; here are Buzz and that first lunar seismometer, photographed by Neil Armstrong: