The Naval Surface Warfare Center, Crane Division in Crane, IN recently issued three contracts for various sonobuoys. Sonobuoys are used to detect and identify moving underwater objects by either listening for the sounds produced by propellers and machinery (passive detection), or by bouncing a sonar “ping” off the surface of a submarine (active detection). They usually float, or have at least some part of them that does. Specialized sonobuoys can also detect electric fields, magnetic anomalies, and bioluminescence (light emitted by microscopic organisms disturbed by a passing submarine); as well as measuring environmental parameters like water temperature versus depth, air temperature, barometric pressure, and wave height.
Sonobuoys are generally dropped from aircraft or helicopters that are equipped with a means to launch them, and electronic equipment to receive and process data sent by the sonobuoy. They can also be launched from ships. The total for these three contracts is $42.2 million.