BERLIN (AP) — The European Space Agency says it has agreed to provide several modules for NASA's planned outpost around the moon, in return for a chance to send European astronauts to the lunar orbiter.

ESA said Tuesday that its director-general, Jan Woerner, signed a deal with NASA chief Jim Bridenstine to provide “essential elements” for the mini space station, known as Artemis Gateway.

ESA said this includes the main habitat for astronauts visiting the lunar outpost, and a module that provides communications and refueling capability along with a window for the crew to observe the moon.

The agency said it will receive “three flight opportunities for European astronauts to travel to and work on the Gateway" as part of the agreement.

NASA aims to use the Gateway as a staging post for missions to the moon and eventually to Mars.

ESA previously agreed to build two service modules providing power, propulsion, water and oxygen for NASA's Orion spaceship taking astronauts to the Gateway.

NASA said it plans to sign further agreements with other international partners for the Gateway.