As the astronauts prepared for sleep, there were a few minutes of concern: Heads of Mission at SpaceX headquarters in California warned the crew that around 1:43 p.m. east coast time, a piece of space debris would pass the capsule.

The astronauts were instructed to put on their spacesuits, return to their seats, and lower their protective visors.

With the growing number of rocket launches and satellites – especially with the spread of constellations in orbit like SpaceX’s Starlink system – low-Earth orbit is becoming increasingly crowded with debris such as rocket fragments and dead satellites, and experts on Earth have repeatedly voiced their concern about the risk of collisions. The European Space Agency held a major conference on the subject last week.

The space station, which is about the size of a soccer field, has to adjust its orbit regularly to avoid a piece of space debris. It’s more unusual to find debris on a collision course with anything the size of the Crew Dragon – 27 feet high, 13 feet wide.

For the crew tied to the space station, the object seemed likely to miss the crew kite, and no emergency maneuvers were performed to get out of the way. Due to the uncertainty about the exact location and trajectory of the debris, the spacesuits provided additional protection if the debris collided with the spaceship.

The debris was not immediately identified, and the time of closest approach came and went uneventfully. The crew members then went back to what they had been doing – getting ready to sleep.