These giant symbols etched into the desert are a welcoming message to aliens from Tom Cruise's deeply secretive church of Scientology.

The religion, which believes a sinister extraterrestrial being called Xenu brought billions of people to earth in spaceships similar to DC8 airliners, operates a giant underground base hidden deep within the New Mexico desert.

BBC reporter John Sweeney, who famously clashed with Scientologists during a Panorama report in 2007, travelled to the site dubbed Scientology's 'alien space cathedral', to research a new book.