Sioux Falls-based Raven Industries has been awarded a $6 million contract for its tethered aerostats from the Department of Defense. The contract comes from the Naval Air Warfare Center aircraft division in New Jersey for exportable persistent ground surveillance systems, spare equipment and technical support. Raven’s relationship with the military goes back to the company’s founding in 1956 when it produced high altitude research balloons for the U.S. Navy. Raven Aerostar vice president and general manager Lon Stroschein joined Dakota Midday and explained what tethered aerostats are and how they're used.