https://www.scientificamerican.com/article/the-astronaut-who-never-left-earth/

Stepping out of a capsule no bigger than a modest home kitchen, the four-person crew of NASA’s latest Human Exploration Research Analog study “returned” to Earth last month after a 45-day mission to fictional asteroid Geographos. Although the capsule never actually left NASA Johnson Space Center in Houston, the mission’s results could shape how the space agency’s astronauts someday handle the isolation, confinement and sleep deprivation likely to occur during interplanetary travel.

Crew member William Daniels, a geologist at the University of Massachusetts Amherst, has long adored cosmic exploration. He saw this mission as a small-but-significant step toward deep-space travel—NASA will use lessons from this crew to build protocols for human voyages to Mars. Unfazed at the prospect of sleeping just five hours per night and being subjected to a steady stream of invasive physiological and mental tests, Daniels volunteered to live with three strangers in the cramped capsule, which consisted of a flight deck, a living area and a “hygiene” module. Daniels spoke to Scientific American about his experience.