There are sounds that are strange, sinister and enchanting all at once, and then there is the latest summer hit produced by NASA. The music that the space agency has released is far from your usual type of music since it wasn’t created by a person, nor artificial intelligence, but by the planet Saturn! It was released in an article published in the Geophysical Research Letters journal by a team of astronomers from the University of Iowa.
To explain further, this song came from a recording from a sensor on the Cassini spacecraft, whose mission was to explore the sixth planet in our solar system, and its natural satellites. NASA launched this spacecraft in 1997 and after 20 years of loyal service, the ship finished its last trip in the atmosphere of this gas giant. During the last orbits of Saturn, the sensor revealed a very strange interaction between the planet and Enceladus, one of its moons.
A song from the vibrating plasma
Between the two bodies is a plasma exchange, guided by strong electromagnetic activity. Magnetic field lines pass from Saturn to Enceladus and form a sort of electric circuit which allows charges and ions to move. This movement of plasma creates radio waves, which were then recorded by instruments on board the Cassini spacecraft known as the Radio Plasma Wave Science (RPWS).
Plasma vibration behaves very similarly to air vibrations that we perceive as sounds, but with different materials. Just like in a gaseous or liquid state, plasma is a material state where the electrons move freely and can be easily guided by a magnetic field. On Earth, we find plasma in auroras, which also form when the magnetic field and charged gases interact.
From a radio signal to an audio signal
Once this signal is detected, its characteristics had to be altered by astronomers before we would be able to hear them, and the vibration frequency also had to be reduced by a factor of 5 for the same reason. The length of the song was also compressed, going from 16 minutes to just under 30 seconds. However, it is important to remember that this music is purely fictitious and didn’t really sound this way in space, since no sound can be produced there due to the lack of air.
So, what we are left with is just an idea of what the sound would be like. One thing is for sure, the atmosphere surrounding Saturn isn’t like the one on Earth, and for good reason. Such an interaction doesn’t exist between our planet and Earth because our moon doesn’t have its own magnetic field. That's because it is too far away from our atmosphere where the plasma is present.