Unexplained Sounds Detected in Earth's Stratosphere by Solar-Powered Balloons

Solar-powered hot air balloons are being used by Sandia National Laboratories to detect unique sounds in the Earth’s stratosphere, including mysterious infrasound signals with unknown origins. The balloons are inexpensive and easy to build, and capture low-frequency sound in the Earth’s atmosphere using microbarometers. The technology could potentially be used to explore other planets, such as observing Venus’ seismic and volcanic activity through its thick atmosphere.