In 2006, this question was asked on Who Wants To Be A Millionaire as a £1 million question: Who was the first man to travel into space twice? A) Vladimir Titov B) Michael Collins C) Gus Grissom D) Yuri Gagarin The 'answer' was Gus Grissom. I've been doing a bit of research though and I've no idea whether or not to believe Grissom was the first person to do it twice, or whether Joseph Walker has that accolade. Googling it gives a variety of articles supporting both claimants without explicitly referring to the other. Walker seemingly passed the Karman Line on two of his flights so I don't understand why he isn't the answer to the above question. You could argue that he doesn't qualify as both of these flights were sub-orbital, but then again Grissom's first flight was also sub-orbital so that can't be the explanation (and of course he famously never got to make his third journey due to the Apollo 1 disaster). Any ideas?