NASA's Human Exploration Research Analog (HERA) XIII simulated deep space mission has ended after a record 45 days and the four-man crew is celebrating by getting some kip. Part of the space agency's Human Research Program (HRP), the crew spent over six weeks in the HERA module at the Johnson Space Center in Houston, Texas carrying out a series of experiments that included a study of the effects of sleep deprivation on astronaut efficiency.

As NASA gears up for future manned deep space missions, there are many Apollo era skills to be relearned and many more new frontiers in the human sciences to be explored. A major part of this is the HRP, which uses the two-story HERA module as a habitat/spaceship for simulated deep space missions with an emphasis on crew health and performance.

So far, there have been 13 HERA missions, or "campaigns." The previous 12 lasted seven, 14, and 30 days, but HERA XIII is the longest yet at 45 days. During this time, the four volunteers on their stationary deep space voyage made dry runs of real space mission tasks with the aid of virtual motion devices and other simulators.

The HERA module(Credit: NASA)

But one important factor is how astronauts can cope with insufficient sleep. Future deep space missions will require small crews of only about three, so the teams will be extremely busy and may have to go with reduced hours of sleep for extended periods. Before that happens, NASA wants to know how they will fare and what effect sleep deprivation will have on their performance.

Some previous missions involved the crew surviving on five hours of sleep per night for five nights a week, followed by two nights of eight hours sleep for recovery. And, sorry, no naps and very little caffeine allowed. The HERA XIII crew, consisting of Timothy Evans, James Titus, Mark Settles, and John Kennard, followed a similar routine as scientists studied various factors, such as using bio-mathematical models to predict fatigue and examining the potential for changing habitat lighting to combat it.

"The sleep deprivation was really difficult," says Titus. "It really hindered our normalcy. We are used to working and living our lives at a higher level. During this mission the sleep reduction, the no-nap rule and limited caffeine – went hand in hand to really slow us down."

During the mission, the volunteers were observed in regard to team cohesion, performance, and interpersonal relationships as they carried out mission tasks, like a virtual reality EVA to an asteroid, where they learned how to maneuver in three dimensions and go through pre-spacewalk decompression procedures. Other tasks included using a robotic arm to grab a transport vehicle while sleep deprived.

In addition to going without sleep, the crew had to give up that ubiquitous distraction of the 21st century, the handheld digital device. Instead, they had to fall back on board games and movies to kill time.

Inside the HERA module(Credit: NASA)

"It was really a little bit disorienting," says Settles. "You get in this mode of addressing electronic communications on a daily basis. It was like stepping back 20 years by having a reduced level of constant input of demands on your time from electronic communication."

According to NASA, the HERA XIII crew now plans to talk to their families, eat fast food, and get a decent night's rest.

The next HERA mission is scheduled to begin on August 5 and NASA is also soliciting resumes for future volunteers. Anyone interested in signing up needs to be a healthy non-smoker aged 30 to 55 who must pass a physical and psychological assessment to qualify.

View gallery - 4 images