The European Space Agency will help to build Nasa's next generation spacecraft which could eventually take humans to Mars.
ESA will provide the service module for the Orion spacecraft's Exploration Mission-1 in 2017, the American space agency announced.
The ESA module will fuel and propel the Orion spacecraft, after it launches on Nasa's Space Launch System rocket, and also control its thermal and power systems.
It will be based on the Automated Transfer Vehicle technology which has been resupplying the International Space Station since 2008.
Nasa will build the crew capsule and the launch abort system.
The space agency explained:
"The service module is located directly below the crew capsule and will contain the in-space propulsion capability for orbital transfer, attitude control and high-altitude ascent aborts. It also will generate and store power and provide thermal control, water and air for the astronauts. It will remain connected to the crew module until just before the capsule returns to Earth. "
Unfortunately, we're not quite in sci-fi mode yet.
The Exploration Mission-1 will be an unmanned flight, which will test the performance of the Space Launch System rocket.
It will be followed by Exploration Mission-2, which will include a crew of four astronauts.
"Space has long been a frontier for international cooperation as we explore," said Dan Dumbacher, deputy associate administrator for Exploration System Development at Nasa Headquarters in Wash
"This latest chapter builds on NASA's excellent relationship with ESA as a partner in the International Space Station, and helps us move forward in our plans to send humans farther into space than we've ever been before."
ESA said the decision by Nasa was a "sign of trust and confidence" in its ability to contribute to space exploration.
Thomas Reiter, ESA director of Human Spaceflight and Operations said:
"Nasa's decision to cooperate with ESA on their exploration programme with ESA delivering a critical element for the mission is a strong sign of trust and confidence in ESA's capabilities, for ESA it is an important contribution to human exploration."