Buzz Aldrin

Second human to walk on the Moon during Apollo 11 (1969). During the lunar transit, the Apollo 11 crew observed an L-shaped object through the spacecraft window that paced them for much of the three-day journey. They initially thought it was the S-IVB upper stage booster, but confirmed it was in a different orbit. NASA told them not to discuss it on an open radio channel. In a 2005 interview, Aldrin stated: 'There was something out there that was close enough to be observed, and what could it be?' In a C-SPAN interview, Aldrin made a striking statement about Mars' moon Phobos: 'There's a monolith there, a very unusual structure on this little potato-shaped object that goes around Mars once every seven hours. When people find out about that, they're going to say — who put that there?' In December 2016, at age 86, Aldrin visited the South Pole as part of a National Science Foundation group and was emergency medically evacuated with fluid in his lungs. A tweet from his verified account appeared showing a photo of a pyramid-shaped Antarctic mountain with the text: 'We are all in danger. It is evil itself.' He later denied sending the tweet — his account may have been compromised, or he may have retracted under pressure. The combination of an Apollo astronaut describing an unknown object during humanity's first moon mission, publicly pointing to anomalous structures on Phobos, and the murky circumstances of his Antarctic evacuation makes Aldrin one of the most significant figures in the intersection of space exploration and the unknown.