Washington, July 24 (DPA) Astronauts on board the International Space Station (ISS) Thursday used a robotic arm to place Japanese experiments outside the station.

Japanese astronaut Koichi Wakata and US astronaut Tim Kopra took three payloads - consisting of experiments and communications equipment - out of a carrier on the Japanese Kibo module and transferred them to the laboratory's new porch, where they are being exposed to the extreme conditions of space.

It was the first use of the Japanese-built robotic arm outside of training.

The carrier of experiments and the porch were delivered to the ISS by the space shuttle Endeavour and installed earlier in the current mission.

The experiments include an X-ray camera and a device to study cosmic dust, alongside a communication device to send data between the space station and ground crews in Japan.

Endeavour astronauts have completed three of five spacewalks planned for this shuttle mission, with preparations already underway for the fourth manoeuvre scheduled for Friday.

On Wednesday, the spacewalk was cut short due to a problem with carbon dioxide build-up in one of the astronaut's spacesuits.