Editor's note:

In May, Tim Evans shared his thoughts with The Planetary Society ahead of the HERA XIII mission, which simulated a 45-day mission to visit an asteroid. On June 19, the four-person crew completed their mission, and Evans wrote a follow-up story about the experience.

For more information about the program, visit the HERA website, where you can also apply for a future mission.

After 45 days of confinement, we emerged from the Human Exploration Research Analog (HERA) on the evening of June 19. The mission was interesting, fun and challenging, although I am glad to now be able to get more sleep (more on that shortly!). Our crew of four (James Titus, John Kennard, Mark Settles, and myself) managed to complete the mission, and hopefully we provided lots of useful data for the research teams that were studying us and our interactions.

One of the broad research goals for our mission was to observe the effects of chronic sleep restriction on our individual and team performance. As such, we were limited to 5 hours of sleep for most nights (lights out at 2:00 a.m. and on at 7:00 a.m.), along with limited caffeine consumption (we had coffee, but we were limited in how much of it we could drink and when we could drink it). I knew this would be challenging, and I was not disappointed! After a couple weeks of limited sleep, I felt tired nearly any time I was awake. It was actually interesting to observe how the limited sleep made things such as reading a book or maintaining focus for extended periods of time more difficult. In order to stay awake and a bit more alert, I found myself doing many of my tasks while standing or pacing in the limited space. Even just a little bit of movement was helpful in perking myself up throughout the day.