Sound relies on vibrations traveling through a medium, and Mars does have an atmosphere, meaning the planet is not silent. However, the acoustic experience is profoundly different from Earth’s. The physical properties of the Martian air fundamentally change how sound waves propagate, affecting volume, speed, and pitch. Direct recordings from the surface have confirmed these theoretical predictions, providing a new way to understand the dynamic environment of the Red Planet.
How Sound Travels Through the Martian Atmosphere
The Martian atmosphere presents a unique environment for sound propagation due to its extremely low density. The air pressure on Mars is less than one percent of Earth’s atmospheric pressure at sea level, meaning significantly fewer molecules are available to transmit sound vibrations. This low density causes sound waves to lose energy rapidly as they travel, a phenomenon known as strong attenuation. Consequently, any sound produced on Mars quickly becomes quiet and fades over short distances.
The composition of the air also plays a role, as the Martian atmosphere is overwhelmingly composed of carbon dioxide (roughly 96%). Carbon dioxide molecules absorb and transmit sound energy differently than the nitrogen and oxygen mix of Earth’s air. This chemical composition is responsible for the selective dampening of certain frequencies, altering the overall quality of sound.
The combination of low pressure and high carbon dioxide creates a cold and sparse medium. When a sound wave passes through this thin air, molecular interactions cause a rapid dissipation of acoustic energy into heat. This physical process ensures that sound cannot travel far, resulting in a soundscape of deep silence interspersed with localized noise.
What Acoustic Data Has Been Recorded on Mars
The first direct recordings of the Martian soundscape were captured by the Perseverance rover, which landed in the Jezero Crater in February 2021. The rover is equipped with two specialized microphones, including one on its chassis and the SuperCam microphone mounted on its mast. This acoustic data provides proof of how sound behaves on the planet.
The SuperCam microphone was designed to listen to the rover’s instruments at work. For instance, the SuperCam laser zaps rock targets from a distance, creating a high-frequency shockwave that sounds like a distinct, crackling clack. Analyzing this noise allows scientists to gather data on the physical properties of the rock, such as its hardness.
The microphones have also recorded the mechanical sounds of the rover itself. These include the whirring of motors, the crunch of the wheels moving across the surface, and the noise from the Gaseous Dust Removal Tool. The instruments have successfully captured environmental sounds, such as the whoosh of the Martian wind and the distant, low-pitched hum of the Ingenuity helicopter’s rotor blades.
These recordings have confirmed theoretical models and provided new insights into atmospheric turbulence. The microphones have detected sounds associated with pressure variations from dust devils and subtle acoustic signals from localized electrical discharges. Recording these specific sounds allows researchers to study the micro-level dynamics of the air layer closest to the surface.
Comparing Martian Sounds to Earth Sounds
The combined effects of low density and high carbon dioxide translate the physics of sound propagation into a strange auditory experience. On Earth, sound travels at about 343 meters per second, but on Mars, the speed is significantly slower, averaging 240 to 250 meters per second.
The most unique feature is the existence of two distinct sound speeds, caused by the CO2-rich atmosphere. Low-pitched sounds (below about 240 hertz) travel at the slower speed of approximately 240 meters per second. Higher-pitched sounds, such as the laser zaps, travel slightly faster, at about 250 meters per second. This difference means a listener would hear high-pitched elements arrive a fraction of a second earlier than the lower-pitched elements, creating an unusual delay effect.
The low pressure dramatically limits how far sound can travel before fading completely. On Earth, a sound might be audible from 65 meters, but on Mars, that same sound fades to silence after about 8 meters. This rapid attenuation means Mars is an extremely quiet place, with deep silence prevailing over the landscape.
The high concentration of carbon dioxide severely dampens high-frequency sounds. This effect filters out many of the higher overtones and harmonics that give Earth sounds their richness and clarity. Sounds that do travel are muffled, quieter, and deeper in tone compared to how they would be heard on Earth.