What could be causing microseisms on Mars?

What’s Shaking on Mars? Unpacking the Red Planet’s Microseisms

So, Mars, right? We used to think of it as this dusty, dead rock. Turns out, it’s got a pulse! Not a strong one, mind you, but definitely a detectable rhythm of marsquakes and microseisms. These subtle tremors are like a Martian heartbeat, giving us clues about what’s going on deep inside.

NASA’s InSight mission, which touched down in 2018 and kept its ear to the ground until late 2022, was a game-changer. It was like giving Mars a stethoscope for the first time. Over 1,300 seismic events were recorded! And even though InSight’s mission is over, scientists are still sifting through the data, trying to figure out what’s causing all the shaking.

The Martian Core is Cooling Down

One of the main suspects? The planet’s gradual cooling. Unlike Earth, with its shifting tectonic plates, Mars has just one big, solid plate. As the interior cools, it shrinks, and that puts stress on the crust. Think of it like an old leather belt that’s a bit too tight – eventually, it’s going to crack. These cracks are faults, and when they slip, boom – you get a marsquake.

The Valles Marineris canyon system is a prime example. This thing is HUGE – a canyon stretching thousands of kilometers! Scientists suspect it’s the remains of an ancient fault line. In 2021, InSight picked up a magnitude 4.2 quake coming from that area, basically confirming that Valles Marineris is still active. Pretty cool, huh?

And then there’s the volcano question. Mars might not have active volcanoes today, but it was a volcanic hotspot in the past. Regions like Cerberus Fossae and Tharsis Montes are covered in ancient lava flows. Some scientists think there might still be pockets of magma lurking beneath the surface, causing the occasional rumble. Actually, recent analysis suggests that half of the big marsquakes we’ve detected are linked to this past volcanic activity in Cerberus Fossae.

Watch Out for Falling Rocks

But it’s not all internal stuff. Mars gets bombarded by meteorites way more often than Earth does. Why? Because its atmosphere is super thin. These impacts can create seismic waves that travel through the planet, giving us a peek at what’s underneath.

InSight actually caught several meteoroid strikes. There was this one big event in December 2021 that was later traced to a brand-new, 150-meter crater! It’s like, BAM! New crater, new data. And get this: some new research using AI shows that these strikes can shake things up way deeper than we thought, all the way down to the mantle. A recent study estimates that Mars gets hit by between 280 and 360 meteorites every year, big enough to make craters bigger than 8 meters across. Talk about a rough neighborhood.

Even the Weather Can Make Mars Shake

Believe it or not, even the Martian weather can cause microseisms. Mars has crazy temperature swings. I mean, we’re talking about going from relatively mild to ridiculously freezing in a single day. All that expanding and contracting can cause rocks to crack and shift.

And wind? Even though InSight’s seismometer was shielded, wind can still cause the ground to deform, creating seismic noise. It’s like the planet is sighing in the breeze.

Is There Water Under There?

Here’s a mind-blower: some studies suggest there might be liquid water hiding in the Martian crust. Scientists have found this weird zone, a few kilometers down, that seems to be full of water-saturated rock. If that’s true, it could seriously affect how seismic waves move through the planet. Imagine a sponge cake, and how vibrations would travel through it differently than a solid brick.

What’s Next for Martian Seismology?

Even though InSight is no longer operational, its legacy lives on. The data it sent back is a goldmine for planetary scientists. We’ve learned so much about Mars’ insides, its seismic activity, and how often it gets hit by space rocks.

InSight could become a blueprint for future missions to other planets. While there aren’t any immediate plans to send another seismometer to Mars, what we learned from InSight will be crucial for designing those future missions. By understanding what causes these microseisms, we’re not just learning about Mars. We’re also getting a better handle on how all rocky planets, including our own Earth, formed and evolved. And that’s a pretty big deal.