This month’s comings and goings at the International Space Station highlight the interdependence of the U.S. and Russian space efforts: Next week, NASA astronaut Mike Hopkins is due to return from the space station aboard a Russian capsule, alongside two Russian cosmonauts. A couple of weeks after that, NASA’s Steven Swanson is to ride another Russian Soyuz craft up to the station, again in the company of two Russians.

Under the current arrangement, NASA astronauts cannot get to and from the station without Russian help, due to the retirement of the space shuttle fleet. The ticket price for each astronaut is $70 million, payable to the Russians.

The United States and Russia are not just “joined at the hip” on the space station. Numerous other rocket projects rely on either Russian or Ukrainian space hardware and services. Even U.S. national security satellites are powered into orbit on an American rocket with a Russian-built rocket engine.