NASA saw it coming and the International Space Station's crew of six was evacuated to escape capsules attached to the station.
The move was just a precaution. NASA said the discarded chunk of a Russian rocket was barely close enough to be a threat. The astronauts - two Americans, three Russians and a Dutchman - woke up early and went into two Soyuz vehicles ready to rocket back to Earth just in case.
The debris came closest at 2:38 a.m. ET. It wasn't noticed until Friday, too late to move the International Space Station out of the way.
This is the third time in 12 years that astronauts have had to seek shelter from space junk.
The Associated Press contributed to this report.