New Delhi: Astronauts Shane Kimbrough and Thomas Pesquet have completed the 6.5 – hour spacewalk to prepare the orbiting laboratory for future commercial space taxis and to tackle maintenance chores.US station commander Kimbrough, 49, and French flight engineer Pesquet, 39, floated outside the station`s airlock as the $100 billion complex soared 250 miles (402 km) above Earth.

Kimbrough, making his fifth spacewalk, first upgraded a computer relay box on the station`s central beam, then worked on a docking system for new spaceships in development by Boeing and Space Exploration Technologies, or SpaceX.The U.S. National Aeronautics and Space Administration is making the retrofits in the hope that private companies will begin flying astronauts to the station by the end of 2018.

This would break Russia`s monopoly on crew transportation, a service that costs NASA more than $80 million per person.The first of the space taxis is scheduled for an unmanned debut test flight later this year.During Friday`s spacewalk, Kimbrough disconnected four cables on a docking tunnel to be used by the new commercial space taxis.

On Sunday, ground control teams will use the station`s robot arm to move it onto a different module.The astronauts also lubricated part of the station`s robot arm, replaced cameras on Japan`s experiment platform and tackled other maintenance tasks before heading back inside the station.(With Reuters inputs)