(Bloomberg) -- Operators have lost contact with the Capstone spacecraft, which was launched as part of NASA’s efforts to return to the moon, the US space agency said.

The unmanned craft, owned and operated by Advanced Space LLC, was launched on June 28 from New Zealand by Rocket Lab USA Inc. After six days, Capstone separated from an upper stage and began a four-month journey to the moon, NASA said in a July 4 blog post. 

The spacecraft, the first privately owned vehicle meant to orbit the moon, is “currently not in contact” and its supporting team is trying to determine the cause and re-establish communications, Sarah Frazier, a NASA spokeswoman, said in an interview.

Capstone’s primary objective is to test the orbit to be used by Gateway -- a small NASA space station that is to be a staging area for trips to the lunar surface. It will include docking ports for visiting spacecraft and a place for crew to live and work.

Gateway is part of NASA’s Artemis Program, which plans to return astronauts to the lunar surface as early as 2025, renewing human exploration of the moon and progressing toward the exploration of Mars.

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