WASHINGTON, Sept. 27 (Xinhua) -- The U.S. National Aeronautics and Space Administration (NASA) and its Russian counterpart Roscosmos signed a joint statement on building a "deep space gateway" in lunar orbit, NASA said Wednesday.

In the agreement signed at the 68th International Astronautical Congress in the Australian city of Adelaide, NASA and Russia's Roscosmos State Corporation for Space Activities formed cooperation in building a crewed space station orbiting the moon.

"This joint statement reflects the common vision for human exploration that NASA and Roscosmos share," NASA said in the statement.

The concept of "deep space gateway", still in formulation, was first proposed by NASA in March, which conceived it as a crew tended spaceport in lunar orbit to "serve as a gateway to deep space and the lunar surface."

According to NASA, the spaceport will have a power bus, a small habitat to extend crew time, docking capability, an airlock, and will be serviced by logistics modules to enable research.

"Both agencies, as well as other International Space Station partners, see the gateway as a strategic component of human space exploration architecture that warrants additional study," NASA said.

Robert Lightfoot, acting administrator at NASA Headquarters in Washington, said that "statements such as this one signed with Roscosmos show the gateway concept as an enabler to the kind of exploration architecture that is affordable and sustainable."

NASA said it's working with its partners to "identify common exploration objectives and possible missions for the 2020s."

NASA has also been engaging the U.S. industry in habitation concepts for the gateway and for the deep space transport that would be needed for Mars exploration, the U.S. space agency said.

Five full-sized prototypes of habitation systems are expected to be complete in 2018, it added.