The Edge of Known Space (part 3)

Another factor that is an obvious challenge for space-goers is temperature. Obviously, the vacuum of space is extremely cold, but a less obvious consideration is our own body heat. Space suits are designed to insulate the astronaut and protect him/her from the freezing temperatures of space, but the astronaut's own body heat can be a significant danger as well. In 1966, astronaut Gene Cernan was the third person to attempt an EVA (extra-vehicular activity) in space, and part of his three hour spacewalk included testing the first Astronaut Maneuvering Unit. Despite his air-cooled spacesuit, his faceplate fogged up so badly that he was completely blind in space, and his pulse hit 195 beats per minute—NASA had to cut his spacewalk short to save his life. In another instance, Russian cosmonaut Alexander Kaleri began to overheat during his spacewalk in 2004, due to a single bent tube in the water-cooled system that kept his suit from overheating. Death by your own body heat is a serious hazard that space-explorers must contend with. It's amazing how fragile and precarious space exploration can be, and how explorers can even become a danger to themselves in such a foreign environment!