A few days ago, it was reported that NASA’s InSight lander had found evidence for an oddly pulsating magnetic field, a more magnetic crust than expected and – maybe – the existence of a global reservoir of subsurface water.
Now, there is an additional update regarding InSight’s findings: the lander has seemingly detected multiple “marsquakes” since April, the Martian equivalent of earthquakes, as well as other odd sounds.
The seismic quakes and other sounds would be faint to the human ear, but InSight’s seismometer, called the Seismic Experiment for Interior Structure (SEIS), is much more sensitive to such tiny vibrations. SEIS was provided to NASA by the French space agency, Centre National d’Études Spatiales (CNES), and its partners.
SEIS searches for the seismic signals of marsquakes, which can tell scientists a lot about the planet’s interior and subsurface geological activity.
The sounds of two of the marsquakes are embedded below, from sol 173 (May 22, 2019) and sol 235 (July 25, 2019):
The sounds are subtle, so you have to listen closely and use headphones. The first quake had a magnitude of 3.7 and the second quake a magnitude of 3.3.
InSight first deployed the seismometer on Mars’ surface last Dec. 19, 2018, but things remained pretty quiet for some time after last. Finally, last April, the instrument detected its first potential marsquake. Since then, more than 100 possible quakes have been detected, with 21 of those considered to be actual quakes and not just other random noise. Interestingly, the first quake detected had a higher-frequency signal than any of the ones that followed it.
So what do the quakes suggest to scientists? They indicate that Mars’ crust is not quite like Earth’s quite wet crust, but not like the Moon’s much drier crust, either, but somewhere in-between. The Martian quakes can ring for about a minute, compared to typically shorter ones on Earth.
While InSight’s seismometer has successfully heard its first marsquakes, it has also heard other unusual noises as well, which need to be filtered out.
“It’s been exciting, especially in the beginning, hearing the first vibrations from the lander,” said Constantinos Charalambous, an InSight science team member at Imperial College London. “You’re imagining what’s really happening on Mars as InSight sits on the open landscape.”
These additional noises can come from movement of the lander’s robotic arm, wind gusts, and delicate parts within the seismometer itself expanding and contracting with changing temperatures. The seismometer noises resemble “dinks and donks” and are heard mostly in the evening.
The confirmation of marsquakes adds to the intriguing results reported previously. InSight is showing that Mars is still not completely dead, geologically-speaking, with the subsurface more active than anticipated. And the possibility of large amounts of water deep below the surface is exciting of course, for it would greatly bolster the chances of there being some kind of life still existing today.
Unlike other landers or rovers, the InSight mission focuses on studying the interior of Mars, looking for evidence of geological activity below the surface for clues as to how active Mars is today and how the planet evolved from a once wet world to the cold, dry desert we see today.
InSight was launched on May 5, 2018, on a United Launch Alliance Atlas V “401” rocket from Vandenberg AFB, California. It landed in the Elysium Planitia region on Mars on Nov. 26, 2018.
More information about InSight is available on the mission website.