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 the objects were not aliens, but rather test balloons launched by a South Dakota aerospace subsidiary.
“Sorry, not aliens,” the NWS tweeted in response to the calls it received.
The high altitude balloons were launched by Raven Aerostar, a subsidiary of Raven Industries.
“As a South Dakota company and the world leader in stratospheric balloon technology, our team conducts stratospheric balloon flights throughout the year, and many of them are launched from our dedicated hangar near Baltic, SD,” said Aerostar president Jim Nelson. “Two of our Thunderhead Balloon Systems are currently over Sioux Falls.”
The balloons, which look like hot air balloons, operate miles above the surface of the earth. Once the balloon reaches the stratosphere, it changes from a teardrop to a pumpkin shape, South Dakota Public Broadcasting reported.
Aerostar said 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.
“Research and development flights help us test the accuracy of our wind models, monitor the durability and functionality of the balloon components in the harsh conditions, and improve our ability to navigate to an area and then stay over that area for an extended period of time,” Nelson said.
Aerostar provides high-altitude balloons to the U.S. Department of Defense. The company said the balloons are cheaper than satellites and can operate for months at a time.