LEARNING TO LIVE ON A MARS DAY: PHOENIX MARS LANDER MISSION
Learning to Live on a Mars Day: Fatigue Countermeasures during the Phoenix Mars Lander Mission
Laura K. Barger, PhD1,2; Jason P. Sullivan, BS1; Andrea S. Vincent, PhD3; Edna R. Fiedler, PhD4; Laurence M. McKenna, MEngSc1; Erin E. Flynn-Evans, PhD1,2; Kirby Gilliland, PhD3; Walter E. Sipes, PhD5; Peter H. Smith, PhD6; George C. Brainard, PhD7; Steven W. Lockley, PhD1,2
1Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA; 2Division of Sleep Medicine, Harvard Medical School, Boston, MA; 3Cognitive Science Research Center, University of Oklahoma, Norman, OK; 4Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX; 5Operational Psychology, Johnson Space Center, NASA, Houston, TX; 6Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ; 7Department of Neurology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA
To interact with the robotic Phoenix Mars Lander (PML) spacecraft, mission personnel were required to work on a Mars day (24.65 h) for 78 days. This alien schedule presents a challenge to Earth-bound circadian physiology and a potential risk to workplace performance and safety. We evaluated the acceptability, feasibility, and effectiveness of a fatigue management program to facilitate synchronization with the Mars day and alleviate circadian misalignment, sleep loss, and fatigue.
Operational field study.
PML Science Operations Center.
Scientific and technical personnel supporting PML mission.
Sleep and fatigue education was offered to all support personnel. A subset (n = 19) were offered a short-wavelength (blue) light panel to aid alertness and mitigate/reduce circadian desynchrony. They were assessed using a daily sleep/work diary, continuous wrist actigraphy, and regular performance tests. Subjects also completed 48-h urine collections biweekly for assessment of the circadian 6-sulphatoxymelatonin rhythm.
Measurements and Results:
Most participants (87%) exhibited a circadian period consistent with adaptation to a Mars day. When synchronized, main sleep duration was 5.98 ± 0.94 h, but fell to 4.91 ± 1.22 h when misaligned (P < 0.001). Self-reported levels of fatigue and sleepiness also significantly increased when work was scheduled at an inappropriate circadian phase (P < 0.001). Prolonged wakefulness (≥ 21 h) was associated with a decline in performance and alertness (P < 0.03 and P < 0.0001, respectively).
The ability of the participants to adapt successfully to the Mars day suggests that future missions should utilize a similar circadian rhythm and fatigue management program to reduce the risk of sleepiness-related errors that jeopardize personnel safety and health during critical missions.
Barger LK; Sullivan JP; Vincent AS; Fiedler ER; McKenna LM; Flynn-Evans EE; Gilliland K; Sipes WE; Smith PH; Brainard GC; Lockley SW. Learning to live on a Mars day: fatigue countermeasures during the Phoenix Mars Lander mission. SLEEP 2012;35(10):1423-1435.