The usage of tiny microphones on NASA’s Perseverance Mars rover has proven incredibly useful to each engineers and scientists. The sensors can discover wind gusts and even hear the staccato popping sounds manufactured from laser pulses made by the rover’s instruments.
Similarly, the swirling blades of the Ingenuity Mars helicopter have been picked up by these microphones, as has the pumping rhythm of the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE), an oxygen-making experiment aboard Perseverance.
Based on the invaluable scientific contributions these instruments have made aboard Perseverance because it rolls about inside Jezero Crater, it is time to turn up the quantity on microphones for extra-planetary exploration.
Related: The sounds of Mars: NASA’s Perseverance rover puts ears on the Red Planet for the first time
International efforts
Timothy Leighton is a professor of Ultrasonics and Underwater Acoustics on the UK’s University of Southampton in England. He continues to support international efforts to incorporate acoustic sensors on probes headed for Mars and to a wide range of other space destinations.
“The work goes beyond just hearing sounds,” Leighton told Space.com, as they might be analyzed to inform researchers concerning the wind, temperature, chemistry and turbulence on Mars. “You possibly can tweak out an enormous amount of data by listening to sounds,” Leighton said.
Leighton has been focused on raising public interest to make sure that policymakers make an effort to place microphones on other worlds.
Software package
To that end, Leighton supplied an acoustical simulation device to a neighborhood planetarium to be used in live shows geared toward engaging and provoking children in science and engineering. The software package plays audio simulations that estimate the sounds produced by natural phenomena — sounds of thunder, wind and cryo-volcanoes — to accompany visual presentations and planetarium shows concerning the exploration of Venus, Mars, and Saturn’s largest moon, Titan.
The software package can even modify the speech of the presenter, or an audience member, to simulate their voices as they might sound on whatever off-Earth world is under discussion.
“The exercise has also allowed a proof of the science and engineering behind the creation of the sounds,” Leighton said. “Nonetheless the really major breakthroughs are those coming from the Perseverance science and engineering,” he said, “and in comparison with that, my contributions are a small thing, just work to get people interested.”
Audible range
Following its landing in February 2021, NASA‘s Mars Perseverance rover is the primary mission to the Red Planet that has been capable of return acoustic data from the surface within the audible range.
The wheeled robot is outfitted with two microphones: The SuperCam microphone, positioned on top of the rotating rover’s mast and the entry, descent and landing microphone fixed on the body of the rover.
The SuperCam microphone has recorded wind and turbulence noise and various equipment operations. It has also made it feasible to create on-the-spot analyses of how sound waves behave in the skinny, carbon dioxide-dominated Mars atmosphere.
Acoustic signatures
Recorded sounds on Mars originate from three most important sources: The atmosphere (created by turbulence and wind), the shock-waves generated by the Laser-Induced Breakdown Spectroscopy (LIBS) instrument on the SuperCam, and hardware-induced artificial sounds equivalent to the motors on the rover turning its wheels.
As an example, in keeping with Michael Hecht of the MIT Haystack Observatory, MOXIE was heard in nearly every run by the SuperCam microphone.
“That one is at the highest of the mast and intentionally isolated from the body so the sound goes through the air,” Hecht told Space.com.
One other hardware-induced artificial sound comes from the high-speed spinning blades of the Ingenuity helicopter. Several Ingenuity flights were close enough for his or her acoustic signatures to be recorded by the SuperCam microphone.
Perseverance playlist
There may be now a “Perseverance playlist” featuring hours of Martian sounds, said researchers Ralph Lorenz of the Johns Hopkins University Applied Physics Laboratory and Baptiste Chide of the Los Alamos National Laboratory’s Space and Planetary Exploration Team.
At a recent meeting of the Acoustical Society of America, the researchers reported that probably the most outstanding sound stems from flights of the Ingenuity chopper.
In a related paper, Lorenz said that the helicopter data gathered is critical to understanding the acoustic environment of Mars. Also, those acoustic measurements are a useful diagnostic tool to appraise the flight characteristics of the robotic helicopter, which may possibly be relevant in supporting future Mars sample return operations.
Lorenz and fellow researchers also note that NASA’s Dragonfly rotorcraft lander mission to Saturn‘s icy moon Titan, presently in development, could carry a number of microphones which can gauge rotor/motor operation and maybe also detect wind noise or other environmental sounds.
Pressure signals
With a view to plan missions with microphones or other acoustical sensors for other worlds, and to design those instruments appropriately, Leighton said it is beneficial to predict the character of the signals they may detect. Such predictions could, for instance, discover early that a planned single microphone system ought to be replaced by a three-microphone system, he said.
Atmospheric lightning on Venus is assumed to occur at roughly half the speed seen on Earth. Along with the possible generation of acoustic signals resulting from lightning, dust devils swirling across Mars would also generate pressure signals, said Leighton.
Then there may be evidence suggesting the possible presence of cryo-volcanoes on Neptune‘s moon Triton, Jupiter’s moons Io and Europa, and Titan and fellow Saturn moon Enceladus, Leighton identified.
Bottom line: It seems that outer space is usually a invaluable sound stage.