An astronaut has dropped a small mirror into space by accident, Nasa has said.
Commander Chris Cassidy lost control of the mirror while leaving the International Space Station for a spacewalk to work on batteries, and it floated away at about a foot per second, the space agency said.
The object is now just one of the vast amount of space junk that is in orbit around the Earth.
Mission Control said the mirror somehow became detached from Cassidy's spacesuit. The lost item posed no risk to either the spacewalk or the station, NASA said.
Spacewalking astronauts wear a wrist mirror on each sleeve to get better views while working. The mirror is just 5 inches by 3 inches, and together with its band has a mass of barely one-tenth of a pound.
Cassidy and Bob Behnken, who followed him out without mishap, were conducting the first of at least four spacewalks to replace the last bunch of old station batteries.
Once the six new lithium-ion batteries are installed, the orbiting lab should be good for the rest of its operational life, according to NASA. The big, boxy batteries — more powerful and efficient than the old nickel-hydrogen batteries coming out — keep the station humming when it's on the night side of Earth.
The battery replacements began in 2017, with previous crews putting in 18 lithium-ion batteries, half as many as the old ones replaced.
Cassidy and Behnken have six more to plug in before the job is complete. It's cumbersome work: Each battery is about a yard (meter) tall and wide, with a mass of 400 pounds (180 kilograms).
Their spacewalks are expected to continue through July before Behnken returns to Earth in August aboard a SpaceX Dragon capsule.
Behnken and Doug Hurley made history at the end of May with SpaceX's first astronaut launch.
This was the seventh spacewalk for both men. Each has spent more than 30 hours out in the vacuum of space.
Additional reporting by Associated Press