Early yesterday morning, NASA astronaut Chris Cassidy was peering through a window aboard the International Space Station when he spotted something strange and unidentifiable coursing through space alongside the orbital outpost.

When he couldn't discern for himself what the mysterious object was, Cassidy phoned home to mission control. At first, they didn't know either, but NASA reported later that day that they'd sussed it out.

“Earlier this morning (Aug. 19), Chris Cassidy had noted an object that was floating past the station near the station’s Progress 52 cargo ship,” said the NASA TV narrator. “That object has been identified by Russian flight controllers as an antenna cover from the Zvezda service module.”

h/t Ian O'Neill, who originally had his money on a Tribble invasion.