For years, Mars has been seen and not heard, but the InSight lander has changed all that. NASA has now released a symphony of sounds captured by the InSight lander from the Red Planet, including the low rumbles of marsquakes that it was designed to detect, as well as howling winds, metallic “dinks and donks”, and other eerie whistles and ticks.
Using its sensitive seismometer, InSight captured its first marsquake back in April, a good six months after touching down on the Red Planet. Since then, the lander has detected a total of 21 events that are strongly believed to be quakes. Another 80 or so events are of background noise, including wind, movements of the robot arm, and the equipment cooling down after a day in the hot Sun.
Below you can listen to two of the clearest quake recordings. Normally below the range of human hearing, they've been sped up and lightly edited, according to NASA. The first was captured on Sol 173 (or the 173rd Martian day of the InSight mission), and is estimated to have had a magnitude of 3.7. The second was recorded on Sol 235, and registered a magnitude of about 3.3.
These past few months of quakes has taught scientists about the makeup of Mars itself. It turns out that the Red Planet’s crust is like a mix of both the Earth’s and the Moon’s crusts. Earth is seismically very active, with tectonic plates rubbing up against each other regularly. When the crust cracks, water eventually patches them back up, allowing sound waves to pass through old fractures. That means they’re usually gone from a given spot within seconds.
On the Moon however, seismic activity is far quieter but events can last much longer. That’s because there’s no running water to seal fractures, so they stay open and reverberate the sound waves for dozens of minutes at a time. Mars is somewhere in the middle, with its mostly dry surface staying fractured for longer and causing seismic waves to hang around for about a minute.
But not all sounds are seismic. Insight has picked up plenty of other noises that the science team is learning to recognize. Wind whistling past the spacecraft is a common one, particularly during the Martian day. When the robot arm moves, it can be heard as a sharp, hollow noise.
The most fascinating noises though are what the science team has coined “dinks and donks”. These short, repeating noises usually come out at night, and alternate between sounding like dripping water, ticking clocks, and tapping on a hollow metal pipe.
The below recording was made on Sol 226, just after the sun set.
The team says these dinks and donks are coming from inside the seismometer, as parts rub against each other as they expand and contract. This is caused by the materials cooling off after being heated in sunlight, the same way a car engine will make ticking noises after it’s turned off.
You can listen to some of the sounds in the video below.
Source: NASA JPL