New work is being carried out on the outside of the international space station in preparation for the eventual arrival of new commercial space taxis.<br /><br /> Two US astronauts have made their third spacewalk in a week to install communication and navigation equipment.<br /><br /> Images from NASA showed Barry Wilmore and Terry Virts during a seven-hour spacewalk.<br /><br /> The ISS is preparing for the eventual arrival of spacecraft being developed by Boeing and SpaceX.
