Washington, Mar 24 (IANS): Starting Friday, Expedition 50 astronauts will conduct up to three spacewalks outside the International Space Station (ISS) to prepare for the future arrival of commercial crew spacecraft and upgrade station hardware, NASA said.

The second and third spacewalks are scheduled for March 30 and April 6.

The spacewalks will be the 198th, 199th and 200th in support of space station assembly and maintenance.

The first spacewalk will prepare the Pressurised Mating Adapter-3 (PMA-3) for installation of the second International Docking Adapter, which will accommodate commercial crew vehicle dockings, NASA said.

The PMA-3 provides the pressurised interface between the station modules and the docking adapter.

Expedition 50 Commander Shane Kimbrough of NASA and Flight Engineer Thomas Pesquet of ESA (European Space Agency) will disconnect cables and electrical connections on PMA-3 to prepare for its robotic move on March 26.

PMA-3 will be moved from the port side of the Tranquility module to the space-facing side of the Harmony module, where it will become home for the docking adapter, which will be delivered on a future flight of a SpaceX Dragon cargo spacecraft.

The spacewalkers also will install on the starboard zero truss a new computer relay box equipped with advanced software for the adapter.

The second spacewalk will feature Kimbrough and Flight Engineer Peggy Whitson of NASA reconnecting cables and electrical connections on PMA-3 at its new home on top Harmony.

The final spacewalk will tentatively feature Whitson and Pesquet replacing an avionics box on the starboard truss called an ExPRESS Logistics Carrier, a storage platform, NASA said.

While Kimbrough's two spacewalks will be the fifth and sixth of his career, Whitson will be making the eighth and ninth spacewalks of her career - more than any other female astronaut.

Pesquet will undertake the second and third spacewalks in his career.