One man has preserved letters written by soldiers back to the Revolutionary War era.
Mars is getting crowded.
Last week, the InSight lander touched down to start studying marsquakes. Marsquakes, as the name implies, are just like earthquakes, but on Mars. And understanding these quakes will help us prepare for future Mars missions.
You wouldn’t want to build a house in a Martian lava tube and then have that tube collapse on your head in a marsquake, would you? No. But that’s a scenario for the future.
For now, knowing how frequently and at what magnitude Mars shakes will not only reveal how tectonically active the planet is, but will also offer clues about how it evolved. As well, marsquakes will allow the team to directly map the planet’s insides. As they travel, seismic waves move through materials of differing density and composition, sometimes being bounced off boundaries between layers, and they carry information about what they’ve moved through before reaching the seismometer.
“Once you are able to locate the event, then you can learn what the structure of the planet is along that wave path,” Weber explains. “Really, all we need once we get there is just to record some quakes!”
And these will help us understand quakes here better.
For the most part, earthquakes on our planet occur because of plate tectonics, the mechanics that occur as the plates that make up Earth’s outer shell glide over the mantle, Earth’s rocky innards. These tectonic plates are constantly moving — roughly between 2 and 4 inches (5 to 10 centimeters) each year, according to Britannica — bumping into and slipping past one another. Sometimes, when a plate is moving past another plate, its rough edge gets stuck and stops, while the rest of the plate continues to move. Because that part of the plate is stuck, it stores up the energy it would normally use to move, eventually catching up to the rest of the plate and releasing all the energy as seismic waves — causing shaking, according to the U.S. Geological Survey (USGS).
But Mars doesn’t have a fragmented outer shell like Earth does. So how does it still have quakes? Well, it turns out, other phenomena can also cause these seismic waves, such as the stress of a slightly shrunken surface caused by planetary cooling, the pressure of magma pushing up toward the surface or even meteorite impacts, according to NASA.
But these vibrations, in comparison to Earth’s, are very small.
With another lander on Mars, we’ll get the latest on space exploration within our solar system.
- Nadia Drake Contributing writer, National Geographic; @nadiamdrake
- Ravi Prakash Systems engineer, InSight, NASA
- Suzanne Smrekar Deputy principal investigator, InSight, NASA
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