A spacewalking astronaut has added to the pieces of rubbish orbiting the Earth, losing a small mirror as soon as he stepped out of the International Space Station for battery work.
Commander Chris Cassidy said the mirror floated away at about a foot per second.
Mission Control said the mirror somehow became detached from Mr 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 five inches by three inches, and together with its band has a mass of barely one-tenth of a pound.
Mr Cassidy and Bob Behnken, who followed him out without mishap, were conducting the first of at least four spacewalks to replace the last batch 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 operating when it is 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.
Mr Cassidy and Mr Behnken have six more to plug in before the job is complete. It is cumbersome work: Each battery is about a metre tall and wide, with a mass of 180 kilograms.
Their spacewalks are expected to continue through July before Mr Behnken returns to Earth in August aboard a SpaceX Dragon capsule.
Mr 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.