Two astronauts from the US space shuttle Discovery on Friday completed the mission's first spacewalk at the International Space Station (ISS) on Friday, according to DPA. The two US citizens Scott Parazynski and Douglas Wheelock nstalled the Harmony linking module, which is due to be used in December for docking the European space laboratory Columbus, in a temporary location outside the ISS. They are also installed an antenna to a solar sail bracket. The space walk lasted just over six hours.