Houston, we have a podcast. Welcome to the official podcast of the NASA Johnson Space Center, episode 266, Moonquakes.

I'm Pat Ryan. On this podcast, we talk with scientists, engineers, astronauts, and other folks about their part in America's Space Exploration Program.

And today we're going to focus our attention to what's shaken almost a quarter of a million miles out in space.

I have been lucky enough to have lived all of my life in parts of the United States that are not prone to earthquakes.

I haven't avoided hurricanes, but no earthquakes. On top of my limited knowledge of quakes of the Earth, it seems that I recall having been taught that Earth's only natural satellite, the Moon, is a dead body that doesn't have any quaking.

Well, turns out that's wrong. The Moon does have seismic activity, ground motion. And since we're going back there in a few years, we best learn all we can about it.

Today we're going to do intro to Moonquakes with lunar seismologist and planetary scientist Dr. Kerry Nunn. Nunn has a doctorate in seismology from the University of Cambridge,

which she followed with a one-year postdoc at Durham University in the UK, then a fellowship at Ludwig Maximilian University in Munich, and then another at the Jet Propulsion Laboratory, where she is now a research scientist using seismology to study the structure of the Moon.

And she's currently involved in a number of NASA missions that are rewriting what little I thought I knew about lunar structure.

So, let's get educated. Here we go.

For those of us of a certain age, as they say, it was once a scientific fact that the Moon was a dead body.

There was no life there, no water, no air, not even any vibrations, except when it got hit by a meteor digging a new crater.

Kerry Nunn, when did science start to realize that there actually was seismic activity on the Moon?

Well, that's actually interesting, because it's not really until a polar eleven, and even then, nobody's quite sure, because what happens is a polar eleven, so they took a seismometer.

And it had these strange signals, just nothing we have ever seen on a signal.

They looked, but over an hour, even if it's something really small, they can, you know, they rise very slowly, and they decay even more slowly.

They just, it looked like a sound wave, but for an hour, they just, like, this crazy signal.

And so, it's like, so of course, one of the first questions that they had was how did they just set it up wrong?

You know, that they'd done something, you know, something wrong with a seismometer or a wave to stored, or even a wave to digitize, that just something went wrong.

And so they had many, many signals like this.

Because they did see some, the footballs, for the older, and that's kind of on the short period type monitor, but they said that they still need a much longer signal on the mid period type monitor.

And so, yeah, they just looked crazy, and it actually wasn't until they deliberately crashed, they spent, you know, a sent module from a colleague, well, a few months later.

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