Spacewalkers made progress today on preparations at the International Space Station for the arrival of the first commercial space taxis.
During today’s operation, which lasted just over six and a half hours, NASA astronaut Shane Kimbrough and French astronaut Thomas Pesquet disconnected cables and electrical connections on a big piece of equipment known as the Pressurized Mating Adapter-3, or PMA-3.
PMA-3 serves as the interface between the ports on the station’s modules and another apparatus known as the International Docking Adapter, which is built to fit the hatches of SpaceX’s Crew Dragon and Boeing’s CST-100 Starliner.
Both SpaceX and Boeing are still developing and testing those space taxis, but if all goes according to plan, SpaceX says it could launch the Crew Dragon into orbit on an uncrewed demonstration flight by the end of this year.
The first crewed flight to the station is expected to happen no earlier than next year. That would mark the first launch of U.S. astronauts from U.S. soil since the space shuttle fleet’s retirement in 2011.
Unhooking the PMA-3’s connections is just one step in the installation procedure. Astronauts plan to use the station’s robotic arm to move the adapter from the Tranquility module to its new spot on the Harmony module on Sunday.
Kimbrough and NASA’s Peggy Whitson will reconnect the cables and wires during a second spacewalk, set for March 30. They’ll also install shields and covers on the now-vacant Tranquility port.
Whitson and Pesquet will take on a third spacewalk to replace an avionics box on the station’s truss. The box contains electrical equipment and the electronics for science experiments and other hardware stored outside the station.
The replacement box is due to be sent to the station in an Orbital ATK Cygnus robotic cargo capsule. The Cygnus’ launch date is currently up in the air, due to a booster hydraulic issue relating to its Atlas 5 launch vehicle. If the issue can be resolved in time, the third spacewalk is targeted for April 6.