Definition
An astronaut sponsored by a foreign space agency that partners with NASA on cooperative space programs, such as the International Space Station. International Partner Astronauts are trained and qualified to fly aboard NASA spacecraft and serve as crew members on joint missions, but they are employed by their home country's space agency rather than NASA.
Plain English
A space traveler from another country's space program who flies on missions run together with NASA. They aren't NASA employees, but they're trained to fly on NASA spacecraft as part of an international team.
Context Anchor
Seen in spaceflight, crew assignment, and mission planning discussions involving crews from more than one national space agency.
Derivation
International' comes from Latin inter (between) and natio (nation), meaning 'between nations.' 'Partner' comes from Latin partitio, a sharing or division, indicating shared work. 'Astronaut' comes from Greek astron (star) and nautes (sailor), so literally 'star sailor.' Together: a star sailor from a partner nation working alongside NASA.
Why Pilots Care
In space operations, this term helps identify who the crew member represents, how they entered the mission, and what training and duties they are expected to have.
Intuition Check
Do not read this as simply “an astronaut from another country.” Here it means an astronaut connected to a formal space-program partnership.
Example Sentence 1
The mission crew included two NASA astronauts and one International Partner Astronaut from the Canadian Space Agency.
Example Sentence 2
International Partner Astronauts train alongside NASA crews for long-duration station flights.