Two Russian cosmonauts, Alexander Samokutyayev and Sergei Volkov, completed their 6-hour spacewalk on Thursday with a 40-minute delay and returned to the Russian segment of the International Space Station (ISS).

They carried out a manual launch of a mini-satellite and installed new stream video equipment on the station's outer surface.

This was the first spacewalk for Samokutyayev and the third for his colleague Volkov.

The launch of the Kedr mini-satellite, designed to transmit greeting messages in 17 languages, Earth photos and telemetry data from its service systems, was delayed after the cosmonauts discovered that one of its two antennas was missing, but they nevertheless launched the satellite with only one antenna.

The cosmonauts also installed three containers with microorganisms and mushroom spores on the Pirs docking compartment to study their influence on materials used in spacecraft construction.

At the end of their spacewalk, the Russians took pictures holding photos of the first cosmonaut Yury Gagarin, spacecraft designer Sergei Korolyov and Soviet astronautic theory pioneer Konstantin Tsiolkovsky with Earth in the background.