Kelly, who returned to Earth after 340 days in space last year, is working on a memoir about his experience in the space since, and how he has been seeing the planet since. Two excerpts from his article on Time: The mission that I prepared for was, for the most part, the mission I flew. The data is still being analyzed, but the scientists are excited about what they are seeing so far. The genetic differences that appeared between my twin brother Mark and me could unlock new knowledge, not only about what spaceflight does to our bodies but also about how we age here on Earth. Emerging results reveal the condition of my telomeres -- the ends of our chromosomes that indicate our genetic age -- actually improved while I was in space compared to Mark's, contrary to expectations. The studies I worked on show promise in helping scientists reach solutions to health problems that emerge in long-duration spaceflight -- problems such as bone loss, muscle deterioration, damage to vision and the effects of extended radiation exposure. [...] Personally, I've learned that nothing feels as amazing as water. The night my plane landed in Houston and I finally got to go home, I did exactly what I'd been saying all along I would do: I walked in the front door, walked out the back door and jumped into the swimming pool, still in my flight suit. I'll never take water for granted again. Russian cosmonaut Misha Kornienko says he feels the same way. I've learned that showing up early, whether it's to a job interview or a spacewalk, is the only way to stay ahead of the game and be successful. "If you're not five minutes early, you're already late."