Sounds of Space: New 'Chorus' Recording By RBSP's EMFISIS Instrument

Audio of the phenomenon known as "chorus" radio waves within Earth’s magnetosphere that are audible to the human ear, as recorded on Sept. 5, 2012, by RBSP’s Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS). Five six-second "events" are captured in this sample, and they are played end-to-end, one right after the other, without gaps. Credit: University of Iowa 

Researchers from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) team at the University of Iowa have released a new recording of an intriguing and well-known phenomenon known as “chorus,” made on Sept. 5, 2012. The Waves tri-axial search coil magnetometer and receiver of EMFISIS captured several notable peak radio wave events in the magnetosphere that surrounds the Earth. The radio waves, which are at frequencies that are audible to the human ear, are emitted by the energetic particles in the Earth’s magnetosphere.

“People have known about chorus for decades,” says EMFISIS principal investigator Craig Kletzing, of the University of Iowa. “Radio receivers are used to pick it up, and it sounds a lot like birds chirping. It was often more easily picked up in the mornings, which along with the chirping sound is why it’s sometimes referred to as ‘dawn chorus.’”

This recording was made by many members of the EMFISIS team, including Terry Averkamp, Dan Crawford, Larry Granroth, George Hospodarsky, Bill Kurth, Jerry Needell and Chris Piker.

Illustration of RBSP spacecraft with instruments labeled. Credit: LMSAL

Launched on Aug. 30, 2012, RBSP is part of NASA's Living With a Star Program to explore aspects of the connected sun-Earth system that directly affect life and society. LWS is managed by the agency's Goddard Space Flight Center in Greenbelt, Md. APL built the RBSP spacecraft and will manage the mission for NASA.