In the late 1970s, NASA launched two small spacecraft, Voyager I and Voyager II, and sent them through our solar system, past the planets, and then far out into interstellar space.
Voyager 1, now the most distant human-made object in the universe, and Voyager 2, close on its heels, continue their ground-breaking journey, studying the region in space where the Sun's influence ends and the dark recesses of interstellar space begin.
The entire Voyager program is considered by many to be the most productive, and certainly the most cost-effective, space program ever.
Outer space is filled with all sorts of electronic waves. The two Voyager spacecraft detect these electronic signals and then, with radio transmitters as powerful as a small lightbulb, transmit the signals back to earth, where they are converted to audible sounds.
Yes, I know: electronic waves and energy are not "sound." These sounds were derived and created from the transmitted signals by converting the electronic waves to audible frequency. The resulting sounds are fascinating and haunting.