Just before New Year's Eve 1973, NASA's mission control center in Houston lost contact with the crew of Skylab 4. For 90 minutes, no one on the ground knew anything about what was happening in Earth's orbit. The three crew members had been in space longer than any other humans before them. The astronauts were all in orbit for the first time.
All NASA knew is that the rookie astronauts had a tremendous workload but roughly similar to that of previous Skylab missions. They didn't know that the crew had announced a strike and had stopped working altogether.