"Flight engineer Alexander Kaleri heard a sound similar to a flop at 11:00 a.m. on Friday. He told our experts about this, and they are analyzing the possible reasons for what he heard. All systems of the station are functioning normally, no malfunctions have been registered," a high-ranking official of the Russian Mission Control told RIA Novosti Saturday.
"If something serious had happened on board, I would have been told [about it] yesterday and not today morning," he said.
According to the source, the flop sounded only once and it wasn't like a dub of a drum as was reported earlier.
"Anyway, there is no danger for the crew and station," the source said.