The “sounds” recorded by NASA’s Cassini spacecraft during its dives by Saturn are not conventional sound waves (which cannot travel through the vacuum of space) but are electromagnetic waves and plasma waves that were detected by an instrument and then converted into audio frequencies for human hearing.
This was primarily done by Cassini’s Radio and Plasma Wave Science (RPWS) instrument during its 22 “Grand Finale” dives between Saturn and its innermost rings.
🎧 Types of “Sounds” Recorded
The RPWS instrument measured fluctuations in electric and magnetic fields, which were then processed by scientists to create audible clips. The primary phenomena captured were:
- Plasma Waves in the Enceladus Flux Tube: This was one of the most exciting discoveries. Cassini recorded intense plasma waves moving along the magnetic field lines that connect Saturn to its moon Enceladus. When converted, these waves produced eerie, “whooshing” or “whistling” sounds. This provided new insight into the dynamic, electrical current-like relationship between the geologically active moon and the giant planet.
- Auroral Radio Emissions: The instrument detected intense radio emissions generated by the interaction of charged particles (mostly from the solar wind) with Saturn’s powerful magnetic field, creating an effect similar to Earth’s aurora. These were converted into rising and falling tones that sound like an eerie, complex series of static whistles.
- Ring Particle Impacts: During its close-in dives through the gap between Saturn and its rings, the RPWS instrument listened for the impacts of tiny dust and ice particles hitting the spacecraft. The sudden, potent but minute collisions created tiny puffs of plasma, which the instrument detected as “pops and cracks” in the audio. Initial dives showed this region to be surprisingly dust-free, leading to the nickname “The Big Empty.”
🔬 How the “Sounds” Were Created
The conversion process is similar to how a terrestrial radio works, taking an electromagnetic signal and translating it into an audible frequency:
- Detection: The RPWS instrument, using its long antennas, detected the electric and magnetic fluctuations (waves) in Saturn’s plasma environment.
- Conversion: Since the original electromagnetic waves are generally outside the range of human hearing (often in the kilohertz to megahertz range), scientists downshifted the frequencies and compressed the time of the recording to bring them into the human audible range.
- Analysis: These converted “sounds” are a direct representation of the energy being transferred and the particles interacting in Saturn’s magnetic environment, providing valuable data about the planet’s magnetosphere and its interactions with its rings and moons.
You can listen to one of the recordings captured by the Cassini probe as it headed for its date with destiny in this video: Eerie Space Sounds Are Coming From a Strange Bond Between Enceladus And Saturn. This video contains the processed audio of the plasma waves recorded by Cassini, offering a sense of the eerie sounds of the Saturn-Enceladus interaction.
