During a complicated spacewalk on Friday, NASA astronauts Jeff Williams and Kate Rubins successfully installed a new International Docking Adapter (IDA) to the outside of the space station. The six-hour spacewalk helps the space station transition from the era of Space Shuttle transportation to that of privatized spaceflight.

Both astronauts trained for this installation in NASA's Neutral Buoyancy Lab on the ground, going over the sequence of steps to configure the IDA. The adapter was launched to the space station in July onboard one of SpaceX's Falcon 9 rockets. During this spacewalk, it was attached to the end of the ISS's second Pressurized Mating Adapter (PMA-2), which had previously been used to dock space shuttles.

Installing the IDA is a big step toward making NASA’s Commercial Crew Program a reality. For the program, private companies SpaceX and Boeing are developing spacecraft for NASA that can ferry astronauts back and forth from the ISS. Those vehicles are supposed to carry people to station for the first time in late 2017 and early 2018. And when they do, they’ll automatically dock with the station’s now-installed IDA.

But the IDA isn’t limited to just accepting SpaceX and Boeing’s spacecraft. The adapter has been built to the International Docking System Standard — an international standard for spacecraft docks established in 2010. That means any vehicle with a docking port built to this standard could potentially hook up to the station’s IDA in the future.