Monday, March 12, 2012

The sound of a solar storm, and a tour of "audification"

A composer and NASA fellow at Michigan Engineering is turning satellite measurements into sound as a new data mining approach. Here's a demonstration.

It does sound like stardust. That, with maybe a little electronic whale song mixed in.

This "sonification" of some of the most recent solar storm activity illustrates a unique new approach to data mining in the University of Michigan's Solar and Heliospheric Research Group. Its creator is Robert Alexander, a design science Ph.D. student on a NASA fellowship to explore how turning data into sound could help scientists hear patterns or anomalies that their eyes might miss.

For this project, Alexander started with 90 hours worth of raw information from two NASA spacecraft, MESSENGER at planet Mercury and the Solar and Heliospheric Observatory near Earth. (The instrument he used from MESSENGER is the Fast Imaging Plasma Spectrometer, or FIPS, built right here at Michigan. It's said to be the first to register the latest storm.)

In the particular type of sonification he employs, called audification, each data sample becomes a single audio sample. That means 44,100 pieces of information play back as one second of sound at the common sampling rate of 44,100 hertz. So to make sense of the audio and extract anything meaningful from it, Alexander has to stretch it and in this case run it through additional algorithms.

It's a groundbreaking process that he and his colleagues say is giving rise to a new research tool.

"I can listen to a million data points in approximately 22 seconds," Alexander said.

Last year, this technique led to a new discovery: It turns out that a particular ratio of carbon atoms that scientists had not previously keyed in to can reveal more about the source of the solar wind than the ratios of elements they had currently relied on. He's the second author on the paper published in December in Astrophysical Journal.

Alexander, the Solar and Heliospheric Research Group's data sonification specialist, emailed me a detailed explanation of this work, complete with audio snippets. I think it's all worth sharing.
Before you proceed, pull out a nice pair of headphones and set your volume to a very low level.
For starters, have a listen to the heart-beat of the sun, a sound file which I generated by translating 47 years worth of solar proton speed data directly to audio. What we're listening to here is a flow of charged particles called the solar wind.