The International Space Station. NASA NASA says "an unknown piece of space debris" flew uncomfortably close the International Space Station on Tuesday. The debris, which was predicted to zip past the ISS at 6:21 p.m. ET, would have come within 1.39 kilometers (0.86 mile) of the station. However, mission controllers fired the engine of an attached Russian cargo spaceship to move the orbiting laboratory out of the way. The threat of space debris has grown in recent decades more satellites launch, countries test space weaponry, and dead or disabled spacecraft crash into each other. Visit Business Insider's homepage for more stories. A "piece of unknown space debris" passed within several kilometers of the International Space Station on Tuesday night, NASA said in a blog post.Engineers predicted the mystery hunk of space junk would zip by the space station at about 6:21 p.m.