NASA and Roscosmos have reached a formal agreement to maintain the ongoing seat-barter program, which facilitates the cross-utilization of spacecraft to transport international crew members to the International Space Station (ISS), according to SpaceNews.

This arrangement allows astronauts and cosmonauts to be integrated into missions regardless of the origin of the launch vehicle. Under the current parameters of the agreement, personnel may fly on both the Russian Soyuz spacecraft and the SpaceX Crew Dragon. However, the scope of this partnership is specific: it does not currently encompass the Boeing Starliner spacecraft.

By continuing these seat exchanges, both agencies ensure that at least one American and one Russian crew member remain present on the orbiting laboratory at all times. This redundancy is essential for the continued maintenance and operation of their respective segments of the ISS. The reliance on mixed-crew launches provides a safeguard against potential technical delays or grounding of any single vehicle type.

Why It Matters

The exclusion of the Boeing Starliner from this current iteration of the agreement highlights the rigorous certification and reliability standards demanded by international space partners. While Crew Dragon has successfully normalized commercial crew rotation, the Starliner program remains in a phase of proving consistent operational readiness. This dynamic suggests that until the Starliner demonstrates a long-duration flight track record comparable to SpaceX’s fleet, the ISS seat-barter program will remain restricted to established vehicles, potentially slowing the diversification of human spaceflight launch providers for government-sponsored missions.