NASA Ames Research Center - Working A Mars Sol

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Fatigue Countermeasures Group

Since 1980, the Fatigue Countermeasures Group in the Human Factors Research and Technology Division at NASA Ames Research Center has been examining the extent to which fatigue, sleep loss and circadian disruption affect aviation pilot performance. Rotating shifts, night shifts and exceptionally long days are all irregular schedules that potentially can result in sleep disruptions, sleep loss and performance decrements, thus reducing the safety margin. However, such disruptions are not limited to aviation, but also can occur in other operational environments.

Scientists and engineers who will be controlling the operation and data collection of the Mars Exploration Rovers (MER), scheduled to land on Mars in January 2004, will be forced to work irregular schedules. They will be required to perform mission critical NASA tasks in accordance with a Mars day (sol) schedule, which is approximately 39 minutes longer than an earth day. Therefore, individuals will be required to remain awake 39 minutes longer each day, rotating around the clock. Remaining awake the additional 39 minutes every day results in a phase delay further complicated by a rotating shift work schedule. The human body's circadian system programs humans to live on a 24-hour cycle being awake during the day and asleep at night. This 24-hour cycle of sleep/wake patterns also is affected by light exposure, acting as a time giver for the circadian system. Therefore, trying to sleep during the day while being exposed to daylight levels can result in sleep difficulties and trying to work at night when it is dark can result in performance decrements. This is due to misalignments of the circadian and sleep systems, which are out of sync with the environmental time cues.

Although one cannot ever fully adapt to shift work, specific fatigue countermeasures can be implemented to help maintain alertness and reduce fatigue levels. However, proper use of the countermeasures, such as timing, is critical to have the desired effect. Therefore, it is necessary to educate individuals about proper use of fatigue countermeasures and how the circadian and sleep systems interact to regulate fatigue, alertness and performance. MER scientists and engineers have participated in fatigue education workshops to receive information about strategies and scheduling approaches to help them manage their fatigue. These workshops are based on the two-day Fatigue Education Training Module (ETM) that the FCG has offered since 1993 and continues to offer twice a year as part of the 'operational outreach' focus of the FCG. They were developed to transition all of the research findings of the FCG to the operational community.

Little scientific research has been done to investigate what impact living on a Mars schedule of shifting 39 minutes later each day will have on sleep/wake cycles. As part of the FCG's 'performance and countermeasures' focus, Dr. Melissa Mallis, is performing an exploratory study measuring activity and sleep patterns to determine the ability of MER scientists and engineers to maintain Mars consistent sleep/wake cycles while being exposed to the 24-hour light/dark cycle of Earth. The activity and sleep patterns of MER personnel will be recorded during both readiness tests and the 3-month mission.

MER personnel will wear a non-intrusive 'actiwatch' device that measures activity levels and complete a subjective sleep/wake diary to collect data on sleep-wake cycles. The data collected will provide a reliable and objective estimate of the sleep-wake cycle.

The data collected will be used to improve our understanding of the ability of individuals to adapt their sleep/wake cycles to a Mars day (sol) while being exposed to Earth-based time cues. Results will be used in schedule development to help minimize fatigue and maximize performance and alertness for future Mars-related operations.