Wednesday is a big day for the European Space Agency's Rosetta mission. The spacecraft will attempt to safely set down its lander Philae on the surface of Comet 67P/Churyumov-Gerasimenko. Rosetta has been hovering around the comet, making preparations and learning what it can about the flying chunk of space rock. One surprising discovery has to do with oscillations in the comet environment's magnetic field, a phenomenon that can be translated into a kind of song.
Rosetta's magnetometer experiment first picked up the song when it closed in on the comet back in August. "The scientists think it must be produced in some way by the activity of the comet, as it releases neutral particles into space where they become electrically charged due to a process called ionisation. But the precise physical mechanism behind the oscillations remains a mystery," the ESA said.
The oscillations are taking place way below human hearing, so the ESA increased the frequencies to make it audible for people on Earth. The result is a strangely rhythmic sound that starts with a percussive purring and then ramps up into a combination of whooshing and clicking noises at an increasingly high pitch.
"This is exciting because it is completely new to us. We did not expect this and we are still working to understand the physics of what is happening," said Karl-Heinz Glassmeier, principal investigator for the Rosetta Plasma Consortium, a set of five instruments on board the spacecraft designed to gather data on the comet's plasma environment.
Rosetta's long journey from here to a comet (pictures)
If you want to freak yourself out, compare the comet soundtrack to the clicking sounds Predator makes. Philae isn't likely to encounter a toothy alien when it goes in for its historic landing, but we can at least let our imaginations run rampant for a few hours before the lander reports back on its success on Wednesday morning.