The US space agency NASA has released two new audio clips on Tuesday, October 1, recorded by the Interior Exploration using Seismic Investigations or InSight lander on Mars between May and July this year.
NASA revealed in a blog post that the rumbling sounds were nothing but produced by marsquakes, which are far too quiet to be picked up by the human ear.
But thanks to InSight, which is equipped with an incredibly sensitive seismometer called the Seismic Experiment for Interior Structure (SEIS) as it is specifically designed to listen and record such martian sounds.
NASA stated that "Scientists want to study how the seismic waves of these quakes move through the planet's interior, revealing the deep inner structure of Mars for the first time."
The space agency so far detected almost 21 incidents of marsquakes with the help of the dome-shaped SEIS, which is carried by InSight lander that arrived on the Martian surface last year. But mars didn't produce its first rumbling until April 2019.
The agency shared sounds from two recently detected Martian quakes by SEIS. While one of them happened on May 22 (Sol 173), the other incident took place on July 25 (Sol 235) and both are around magnitude of 3.7 and 3.3, respectively.
"The Sol 235 quake becomes particularly bass-heavy toward the end of the event. Both suggest that the Martian crust is like a mix of the Earth's crust and the Moon's," Nasa's Jet Propulsion Laboratory said.
It also added that "Mars, with its cratered surface, is slightly more Moon-like, with seismic waves ringing for a minute or so, whereas quakes on Earth can come and go in seconds."
Even though both the subtle rumbles are below the human range of hearing, the rumbling noise has been speeded up and processed to be audible through headphones.
The Marsequake audios are available here: