Aerospace company’s test balloons prompt calls of concern

SIOUX FALLS, S.D. (AP) — Citizens who called the National Weather Service concerned about some “silvery objects” in the sky around Sioux Falls this week prompted the agency to tweet that they were not aliens, but rather test balloons launched by a South Dakota aerospace subsidiary. The high altitude balloons were launched by Raven Aerostar, a subsidiary of Raven Industries. Aerostar says the balloons have a variety of uses, including monitoring wildfires, expanding cellular networks and military reconnaissance. They navigate by autonomously changing altitude to take advantage of wind currents in the atmosphere. Aerostar provides high-altitude balloons to the U.S. Department of Defense. The company says balloons are cheaper than satellites and can operate for months at a time.