Your path: Eavesdropping On Space
Eavesdropping On Space
by Jan Dabrowski, Ph.D.
Chair, Department of Science and Mathematics
Marylhurst University
How would you like to listen to space?
Technically, without air, you can't actually hear things in space. But space probes pass through regions containing electrically charged particles and strong magnetic fields. These electro-magnetic signals (E&M) can be detected by antennas and magnetic sensors on the spacecraft.
The E&M detectors on the probes gather information about the environment each spacecraft is traveling through. And when processed, this data can be turned into audible sounds.
NASA has collected some of the niftier (if not spookier) sounds from missions to Jupiter and Saturn and you can hear them at the Web site at the end of this article.
Space probes to the giant planets Jupiter and Saturn have been detecting these naturally occurring E&M signals for several decades. These worlds have very strong magnetic fields, which in turn trap electrically charged particles that are ejected from the Sun. This outward rush of electrons and protons from the sun is called the solar wind.
The earth also catches and collects the solar wind with its magnetic field. There are giant particle storage regions surrounding our planet – earth's Van Allen Belts. Earth's magnetism directs particles from the belts to the north and south poles where they collide with the upper atmosphere. The collision transfers energy to our air and we see it as the aurora – the northern and southern lights.
Long before there were space probes to Jupiter, ham radio operators were listening to the sounds from space. Electrons and protons leaking to earth from the Van Allen Belts were detected on short wave radio equipment as whistles, pops and shrieks – very similar to the sounds heard in the vicinity of Jupiter and Saturn.
These are known as "sferics" for "atmospherics." One set of sferics has been dubbed "the dawn chorus" because the sounds resemble the cacophony of bird chirping that occurs in the wild at sunrise.
You can make and detect your own radio signals if you have an AM radio. Many electrical appliances with motors create E&M signals. If you tune an AM radio to a dead (quiet) spot on the dial, and turn up the volume, you'll hear a background hiss. Turn on a blender or hair dryer near the radio's antenna and you will hear pops and static on the radio. If there is a thunderstorm in the vicinity, E&M energy from lightning can also be heard on the AM radio.
That is basically how space probes detect the E&M signals from space. Antennas and magnetic field detectors (magnetometers) on the probes sense the E&M energy of the particles either hitting or passing near the detectors.
Explore some of the sounds from space at this Web site: http://www.jpl.nasa.gov/multimedia/sounds/index-flash.html
Listen to earth's "sferics" here: http://www.spaceweather.com/glossary/inspire.html
