Scientists were listening to a whisper from the surface of Mars.
NASA's InSight captain, who touched Mars in November 2018, gave scientists an unprecedented ability to detect and observe shocks on Mars. The built-in seismometer found its first earthquake in April, and since then, researchers have recorded dozens of potential earthquakes on Mars.
The nature of this shaking is changing what scientists thought they knew about the red planet.
"We have so far assumed that the bark of Mars is similar to the earth's crust," said Simon Steiner, a researcher of the Martian seismology at ETH Zurich. "The fact that the waveform of Mars earthquakes resembles lunar earthquakes gives us a first picture of how the Martian crust is internally structured, so far we could only look at it from outside." NASA
Mars, Moon, and Earth Tangle for Different Causes
The study of seismic activity helps scientists gather the story of how rock planets have formed in our solar system. For example, on earth, tracking how seismic waves move through the interior of the planet helped researchers calculate its core size.
Reading seismic waves on Mars, scientists hope, will reveal clues about how the inside of the plant looks and how it changes.
"Seismology is how you get details," Marc Panning, a seismologist from NASA's InSight team, told Business Insider.
Not all earthquakes are created equal. When the earth is shaken, it's because the tectonic plates in the crust collide along the fault lines. Mars, however, has no tectonic plates. That's why scientists believe that Mars's shocks probably originate from a constant internal cooling process that occurs in most rocky planets. As the core cools down, the material shrinks, causing stress build-up. This eventually cracks the crust and causes a quake.
On earth, the source of seismic waves is easily detectable because the crust consists of a relatively uniform solid rock (which melts and recovers through volcanic activity for millions of years). This rock also has water in it that absorbs energy, causing the waves to die faster. That is why the earthquakes last for only a few minutes. On the moon, however, earthquakes may last for more than an hour.
"Lunar earthquake accumulates in minutes, then it is disparaged for an hour or more, so it looks very different," said Panning. "The cause of lunar earthquakes they look like this is, the surface of the moon is really dry and really broken. In principle, he sits there for billions of years and hits meteorites. "
However, researchers are expecting the earthquakes of Mars to fall further at the earth's edge of the spectrum, because they thought the planets had similar crusts, considering , that Mars had ever had a lot of volcanic activity and water
But the original evidence suggests it might not be the case
How Mars earthquakes change scientists' understanding of the red planet
So far, the length of the Martian Shakes seems to fall somewhere in the middle of the Moon and Earth, about 10 to 20 minutes, and Mars also appears a little more seismically active than the Moon, but much less Earth
Mars's seismic waves also resolve more from the waves of the Earth and more like the lunar earthquakes
"It bounces off all of these broken bits, so it gives you something that lasts a long time," said Panning.
This suggests that the bark of Mars has layers of strong, dry, broken rock like the moon.
The artist's presentation below shows how seismic waves of earthquake on Mars can move through the interior of the red planet.
The animation made by seismologist InSight at ETH Zurich shows the different types of waves the InSight team is studying. Blue waves are the initial bouncing impulses that are rapidly spreading from the source of the quake. As a result, the reds and seismologists can use the lag between them to calculate how far the source of the quake is.
The long waves of red and white that spread along the sides of the animation are surface waves that bounce off material from the bark – their echoes suggest the lunar qualities of the Mars's crust.
Researchers expect the bark of Mars to be drier and shatter than Earth's, but not quite. They still do not know what to do from the new finding.
A lot more to learn
A few dozen mounds on Mars are not enough to reveal the secrets of the red planet.
"The biggest thing we can do with the very small number of events we've seen so far is really to find out how active Mars is," said Panning. "This tells you a lot of information about how Mars is evolving over time."
Until now, Mars's earthquake signals were too weak to offer information about the planet's internal structure under its bark. A man standing on Mars could not feel any of InSight's selected instruments taken.
Indeed, an InSight Seismologist team in Zurich had to amplify these seismic signals by a factor of 10 million to simulate the quake in the magnitude of an earthquake.
For these reasons, InSight's team is still waiting for a big earthquake that travels through the core of the planet.
"Then we can actually begin to make detailed pictures of what the Martian interior looks like," said Panning. "We have a waiting game, and we'll be listening for another year and a half, so we expect to see a lot more."
Meanwhile, the InSight team is trying to fix a landmark mall, a tool that has to dig up 16 feet and take the temperature on Mars. The mole stopped working properly in February.
In the future, Panning would like to see sensors on every planetary body that is shaking, especially Enceladus, a moon on Saturn from which jets of water are fired. Even better than a seismometer: a whole network of them.
"Earth seismology is almost entirely built on data networks," said Panning. "I would like everywhere to put seismometers."