Man in charge of tracking down Nasa's stolen moon rocks
Nasa says 500 moon rocks have gone missing.
The space agency has been collecting samples of moon rocks since 1970 and has put them on loan to scientific institutions around the world.
Radio 5 live Up All Night spoke to Joseph Guntheinz from Texas who is also known as the Moon Rock Hunter.
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Up All Night broadcasts daily 01:00 to 05:00 on Radio 5 live.