You are correct that sound, as we know it on Earth, cannot travel through the vacuum of space. However, NASA researchers and other space agencies have found alternative methods to capture and record "sounds" from other planets and celestial bodies. These "sounds" are not actual sound waves but are often electromagnetic signals or data converted into audible frequencies for scientific analysis and public engagement.
Here's how it's done:
Radio Waves and Data: Many spacecraft and rovers are equipped with instruments that can detect and record various types of signals, including radio waves, magnetic fields, plasma waves, and other forms of radiation. While these signals are not sounds in the traditional sense, they can be converted into audible frequencies using a process called sonification. Sonification maps the data to sound frequencies, allowing scientists and the public to "hear" the patterns and variations in the data.
Atmospheric Sounds: Some planets and moons have atmospheres or exospheres that contain gases or particles that can transmit sound waves. For example, on Mars, which has a thin atmosphere, some instruments on rovers have recorded vibrations caused by wind passing over the rover's structures or antennas. These vibrations are then converted into audible sounds.
Simulations and Representations: In cases where there is no direct data to convert into sound, researchers use simulations and artistic representations to create "sounds" of other planets. These are often based on scientific knowledge of the planet's characteristics, magnetic fields, or other relevant data.
It's important to note that when NASA or other space agencies refer to these recordings as "sounds," they are being somewhat metaphorical. They are using sound as a way to present data and scientific findings in a more relatable and engaging manner for the general public. These "sounds" are not the same as the sounds we experience on Earth, as they are not actual pressure waves traveling through a medium.
So, while we cannot hear actual sounds from other planets in space as we do on Earth, NASA and other space agencies have developed creative ways to present data and scientific discoveries through sonification and other audio representations, enriching our understanding and appreciation of the universe beyond our home planet.