Commander Chris Cassidy, who accidentally dropped a mirror in space as he stepped out of the International Space Station for battery work, called the incident a 'real bummer'! In an interview with news agency Associated Press, Cassidy shared that he had no idea how the small mirror on his sleeve came off. It may have caught on a metal attachment, he said. He saw it disappearing into the darkness, once it fell off. Spacewalking astronauts wear a mirror on each sleeve to see the displays on their chest control panel. Cassidy is on a six-month mission along with two Russians. Their launch was the first manned lift-off for SpaceX, and the first from the US soil in nearly a decade.