On August 5, 2012 (in the U.S., at least), NASA’s Curiosity rover landed on Mars. The rover’s ongoing mission on the alien planet is one of exploration, gathering data about Mars’ climate and geology. Because Curiosity’s voyage to Mars is intended to be a one-way trip—we don’t yet have a way to launch interplanetary shuttles from Mars to Earth—the rover acts as a mobile laboratory, able to perform varied experiments while on Mars' surface. Some of those experiments require geological samples, so Curiosity needs a way to collect the samples and then move them into the lab areas of its confines.
To do this, Curiosity is outfitted with a group of instruments known collectively as SAM, which stands for “Sample Analysis at Mars.” The SAM team, from Earth, instructs the rover to create a series of vibrations which manipulate the positioning of Curiosity’s collection devices. In turn, those devices—now moving at NASA’s command—collect samples from the surface and move the dirt into the analysis area of the device. As a side effect, like any other vibrations, the ones sent from Earth to Mars result in a series of harmonics. Typically, the sounds are none too pleasant, and could hardly be considered music. But August 5, 2013 was a special day.
On that day, as seen above, the SAM team sent a sequence of vibrations consisting of carefully-planned peaks and valleys. Those vibrations weren’t intended to collect samples from Mars' surface.
—in song. If you care to listen, that’s a screenshot from a NASA video available
, and you’ll immediately recognize the tune as that from "Happy Birthday."
So unless an advanced civilization lived on Mars long ago, or unless Elvis truly isn’t dead and instead relocated to a place a little further from the Sun, "Happy Birthday" was the first song every played on the planet Mars.