This author has also proposed that the solar system has already been visited: "‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity

This author has also proposed that the solar system has already been visited: "‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization."[0] The rest of the paper covers the possibility that the ‘Oumuamua object was sent unintentionally to Earth vicinity by an alien civilization. [0] https://arxiv.org/pdf/1810.11490.pdf https://arxiv.org/pdf/1810.11490.pdf