Behavioral Challenges of Space Exploration
Behavioral Challenges of Space Exploration refers to the factors that either contribute to or impede successful and sustained adjustment to the conditions. Those conditions include, but are not limited to, isolation and confinement; constant proximity of other personnel; restricted choices; absence of gravity; hostile outside environment; and, risk of death from imperfect planning, equipment failure, human error, or a catastrophic event, such as a micrometeoroid strike or solar radiation exposure.
The history of exploration contains many examples of serious psychological problems in response to the isolation, confinement, and other stressors of expedition life. Accounts of Adolphus Greely’s disastrous Lady Franklin Bay Expedition , from which only 6 of 25 returned in 1884, affected all subsequent polar explorers. The stories of insanity and cannibalism among the Greely party were known by the members of the Belgian Antarctic Expedition 13 years later when they became trapped in the ice and experienced a deep depression that killed one man and drove another to bizarre acts of psychosis. Roald Amundsen , who performed his apprenticeship as an explorer on that expedition, wrote later that “insanity and disease stalked the decks of the Belgica that winter.” Similarly, the radio operator on the Australasian Antarctic Expedition in search of the magnetic South Pole in 1912 became psychotic and his ranting threatened to drive other members of the group insane, confined as they were to a small hut in the most inhospitable environment on Earth. That experience led Douglas Mawson to recommend to all future explorers that “In no department can a leader spend time more profitably than in the selection of men who are to accomplish the work.” It was in response to these and other experiences that Richard Byrd reportedly included only two coffins, but 12 straightjackets among his supplies during two expeditions to Antarctica in the 1930s. Perhaps, most notable was the psychosis that disrupted the crew of Navy Seabees who were building the facility at McMurdo Sound in 1955–1957 in preparation for the International Geophysical Year . That case occurred soon after isolation and confinement had been implicated in “brainwashing” during the Korean War and led to a long program of research concerning adaptation to Antarctic conditions and expedition leadership, conducted by E.K. Eric Gunderson, Paul Nelson, and colleagues at the Naval Health Research Center.
I am convinced that we have, or will acquire, the basic knowledge to solve all the physical problems of a flight to mars [sic]. But how about the psychological problems? Can a man retain his sanity while cooped up with many other men in a crowded area, perhaps twice the length of your living room, for more than thirty months? … Little mannerisms—the way a man cracks his knuckles, blows his nose, the way he grins, talks, or gestures—create tension and hatred which could lead to murder. (Collier’s April 30, 1954 “Can We Get to Mars?” p. 26.)
Cosmonaut Valery Ryumin (Ryumin 1980) echoed von Braun’s concerns 26 years later when he wrote of his Soyuz space station experience, “All the conditions necessary for murder are met if you shut two men in a cabin measuring 18 feet by 20 and leave them together for two months.”
Analogy as a Research Method
All fields of science and serious inquiry rely on metaphor when access to actual conditions is impossible. Engineers and architects build scale models of buildings, bridges, and aircraft and then subject them to tests of strength or aerodynamics. Medical researchers explore new therapies using what are called “animal models,” a euphemism for rats, pigs, and other contributors to increased human longevity. Economists create mathematical models to test hypotheses about commerce and finance. And behavioral scientists look to analogous conditions when it is impractical, impossible, or unethical to subject humans to extreme stress for long durations. For this reason, many of the technical reports that addressed behavioral issues during the 1960s, in hopeful anticipation of implementing von Braun’s Mars mission after a successful Apollo Program, included references to conditions on Earth characterized by varying degrees of isolation and confinement; mines, caves, submarines, and Antarctic research stations were among the analogs most-frequently suggested for further study.
Underwater habitats were built during this period and “aquanaut” adaptation to the conditions was studied, beginning with Jacques Cousteau’s Conshelf Program in 1962, which tested the feasibility of extended-duration commercial diving operations at extreme depths (Cousteau 1966). Conshelf was followed by the US Navy’s Sealab Program , conducted between July 1964 and October 1965. Roland Radloff and Robert Helmreich (Radloff and Helmreich 1968) discovered a degradation of human performance on complex tasks during Sealab, with some of the decrement associated with personality variables; individuals who were described as “good mixers” achieved more during diving operations and social interaction was strongly correlated with successful adaptation to the isolated and confined conditions. Helmreich went on to identify the personal traits that predict astronaut performance, using the Personality Characteristics Inventory; the three clusters of traits were labeled, “The Right Stuff,” “The Wrong Stuff,” and “No Stuff.” Spence and Helmreich (1978) found that individuals possessing the Right Stuff exhibited high levels of (1) positive instrumentality (attributes reflecting goal orientation and independence); (2) positive expressivity (attributes reflecting interpersonal warmth and sensitivity); (3) mastery (a preference for challenging tasks and striving for excellence), and (4) work (a desire to work hard and perform well) and low levels of (5) negative instrumentality (arrogance, hostility, and interpersonal invulnerability) and (6) verbal aggressiveness (complaining, nagging).
Sealab was followed in 1969–1970 by Project Tektite , which was sponsored by the US Navy, NASA, the Department of the Interior, and General Electric Company; there were four missions of 14 days duration and six 20-day missions, with one mission performed by a crew of five women. Study results included: (1) individual gregariousness was positively correlated with overall performance; (2) privacy was important, especially to individuals who did not relate well to the group; (3) participants slept longer during their mission than during pre- and postmission periods; (4) conversing was the most-frequent leisure activity; (5) the cupola and bridge were the most popular locations within the habitat (for viewing the surrounding environment and communicating with topside personnel); and (6) variation and self-selection (especially for meals) was appreciated.
The US Navy’s program of research in Antarctica, mentioned previously, focused initially on the factors that affected individual adjustment to the austere conditions of the early stations. Nelson (1965) found the primary contributors to adjustment to be enthusiasm to perform work and help comrades; consideration and friendliness; and the capacity to control emotions when among others. Soon after, the emphasis shifted to identifying the individual characteristics that might be used to select personnel for remote duty. The large numbers of Navy and civilian winter-over personnel enabled Gunderson (1966) to identify three clusters of behavioral traits that were correlated with effective performance at Antarctic stations. He labeled the clusters (1) Emotional Stability (calm and even tempered); (2) Task Performance (motivation and proficiency); and (3) Social Compatibility (likability and cheerfulness). Larry Palinkas built upon the Navy research and found that a need for achievement, a characteristic of motivated workers, can have negative consequences when schedules slip due to communication delays, equipment problems, or lack of supplies (Palinkas 1992). Individuals who adapt best to the conditions are those who can adjust expectations when schedules are impossible to meet (Palinkas 2001). This observation is particularly relevant to living and working onboard a space station, which will be addressed later.
In addition to the space analog studies involving Antarctic stations and underwater habitats, several simulations of space operations have been conducted to help identify relevant behavioral issues. Among the earliest was North American Aviation’s 12-day simulation conducted in 1961 in a partitioned area of the factory’s cafeteria. The simulation, directed by aerospace medicine pioneer, Toby Freedman, generated several insights that were incorporated in North American’s Apollo Program proposal. The company was not expected to win the contract, but NASA reviewers were impressed by North American’s attention to detail, which included preliminary data concerning human performance in isolation and confinement based on the simulation study. Later, Joseph Brady conducted a series of laboratory simulations of space operations tasks (e.g., Brady 1992). And most recently, Vadim Gushin and colleagues studied autonomy, communication lag times, personnel selection issues, and interpersonal interactions among the Russian (three), European (two), and Chinese (one) participants in a high-fidelity, 520-day Mars expedition simulation in 2010–2011 (Ushakov et al. 2014). David Dinges and Mathias Basner conducted studies of sleep, interpersonal relations, and individual adaptation during the Russian Mars 520-day simulation; study results showed substantial sleep disturbances and altered behavior over time (Basner et al. 2013, 2014).
With the exception of Sol Sells’s attempt to develop a taxonomy of isolation and confinement (Sells 1973), little attention had been devoted to determining the appropriateness of the various possible analogs to serve as models for future space expeditions. Other events diverted attention from plans for the human exploration of Mars during the late 1960s and nearly two decades would transpire before NASA funded a systematic analog approach to the study of behavioral issues in 1983. That study was distinguished from previous attempts to extrapolate lessons by making no a priori judgments about the conditions that would constitute an appropriate analog. Instead, 13 conditions characterized by various degrees of isolation and confinement (e.g., submarines, research vessels, offshore oil platforms, saturation chambers, Skylab ) were described in terms of 14 dimensions (i.e., duration of tour, amount of free time, size of group, physical isolation, psychological isolation, personal motivation, composition of group, social organization, hostility of environment, perceived risk, types of tasks, preparedness for mission, quality of life support conditions, and physical quality of habitat). The descriptions then were rated by 76 behavioral scientists and spacecraft designers to identify the conditions most similar to the anticipated 90-to-120-day tours onboard a low–Earth orbit space station. The results of the ranking exercise helped focus subsequent interview and archival research on the most relevant analog conditions. At that time, engineers relied on military standards that were modified in response to experimentation and accumulating human experience in microgravity to design spacecraft controls and equipment, but they lacked guidance concerning what were described as “the intangibles of habitability,” the features and other considerations that contribute to successful adaptation and sustained human performance in isolation and confinement. The report, distributed in 1984 and published by NASA in 1986, was welcomed by agency and industry engineers because it provided a checklist of behavioral issues with design implications and supported more than 100 recommendations with data derived from human experience in circumstances similar to living and working in space. Many of the report’s habitability recommendations were incorporated in early space station designs, and some of them survived more than 10 years of reviews and program changes. Among the recommendations were: (1) Design the food system to allow self-selection and variety, and to encourage the crew to eat together; (2) Design the communications system to ensure privacy of personal calls; (3) Enable group leisure activities and Earth viewing; (4) Schedule at least 1 h of uninterrupted leisure time prior to each sleep period; (5) Provide privatized sleep chambers and other areas for crew members to seek periodic opportunities away from close interpersonal contact; and (6) Pay special attention to stowage of materials and supplies (Stuster 1986).
Results of the lunar and Mars-analog research were documented in a 1995 technical report to the Johnson Space Center titled, The Modern Explorer’s Guide to Long Duration Isolation and Confinement: Lessons Learned From Space Analogue Experience and published a year later as, Bold Endeavors: Lessons From Polar and Space Exploration (Stuster 1996). Chapters are devoted to the principles of habitability and the major categories of behavioral issues; as in the previous space station analog report, each chapter ends with a list of specific design and procedural recommendations derived from the research and intended to facilitate adjustment to the special conditions of isolation and confinement. The book was considered to be “required reading” for members of the Expedition Corps , astronauts planning for missions to the International Space Station (ISS) , which became permanently occupied in October 2000; at least one astronaut took copies of the chapter summaries with him to the ISS for reference, and a digital version of the book was later added to the ISS library at the request of another astronaut.
Astronauts resisted studies concerning interpersonal or psychological performance since the days of the Mercury Program , famously described by Tom Wolf in The Right Stuff . The belief was that once an astronaut had been selected and passed a probationary period, he or she had demonstrated the capabilities necessary to perform all tasks under any circumstances; the self-confidence of the initial seven astronauts was a central component of astronaut culture and became institutionalized as policy. Behavioral issues were not considered to be priorities by NASA for this reason, despite the large body of research and anecdotal accounts concerning the effects of long duration isolation and confinement. Efforts from within the agency to focus attention on the issues were resisted. Patricia Santy, Al Holland , Walter Sipes, Chris Flynn, and others had tried to inform operations managers about the issues, but serious attention was inhibited by the characteristic self-confidence and suspicion of psychology that has been a component of astronaut culture since the Mercury Program. That attitude changed as increasing numbers of nonpilot astronauts were added to the Corps and largely as a consequence of NASA’s experience onboard the Russian Mir space station. Seven astronauts spent an average of 140 days each on Mir between March 1995 and June 1998 and when they returned they convinced their colleagues that expeditions of 3 months or more on a space station are qualitatively different from 14-day Space Shuttle missions. Some described Shuttle missions as sprints, compared to the marathons they experienced on Mir. Several of the astronauts read Bold Endeavors upon their return from Mir and recognized the commonality of their experiences with those of previous explorers. The growing realization that long duration space missions require an expeditionary mindset and perhaps additional skills and personal qualities than needed for short missions inspired members of the Astronaut Corps to sponsor development of a training program in 1999 to prepare future space station crews for the experience. The Expedition Corps Training Program consisted of team-building exercises, simulations, training in intercultural relations, and a 2-day seminar designed to sensitize astronauts to the behavioral issues and provide coping strategies and countermeasures to possible problems. Development of the program and astronauts’ increased sensitivity to the importance of behavioral issues suggested that research concerning isolation and confinement finally had been recognized as relevant to space operations. The Administrator’s Conference on Risk and Exploration , held in Monterey, California, in September 2004, provided additional evidence that mission planners now agree with explorer, Roald Amundsen, who wrote, “The human factor is three quarters of any expedition” (Dick and Cowing 2005).
Trivial issues will be exaggerated.
Equipment will break or malfunction.
Good leadership can be more important than good habitability.
Communications with headquarters will be strained, occasionally.
Minor behavioral problems are common, but serious problems are avoidable.
Future space expeditions will more closely resemble sea voyages than test flights.
Humans can endure austere conditions, but perform better with good habitability.
Be prepared for casualties.
Devote special attention to food.
Establish a “spirit of the expedition.”
Test, train, and simulate everything.
Expect weather to affect everything.
“Live off the land” to the extent possible.
Select qualified and compatible personnel.
Design for redundancy and maintainability.
Distribute stowage of supplies and equipment.
Ensure that the crew remains entertained and busy with meaningful work.
The details will be different, but most of the problems that will confront future space explorers are the same problems that troubled explorers in the past.
Astronauts’ recognition of the similarity of previous expeditions to future space exploration contributed to greater acceptance of behavioral research among astronauts. NASA subsequently sponsored many studies using a variety of research methods to better understand the behavioral factors and stressors of space flight. Peter Suedfeld and Daniel Steel provided a comprehensive summary of the work up to the year 2000 in the millennial issue of the Annual Review of Psychology and research and operational experience in space have progressed since then (Suedfeld and Steele 2000). In particular, the National Space Biomedical Research Institute (NSBRI) was formed to administer research concerning a broad range of behavioral issues, including sleep, radiation, lighting, and vestibular function in microgravity, to name a few. NASA’s Behavioral Health and Performance office, located at the Johnson Space Center, expanded its portfolio of ground-based and flight experiments under the leadership of Lauren Leveton to address medical, human factors, and psychosocial issues relevant to expedition-class space missions. The results of these studies have been published in technical reports, scientific journals, books, and design guides.
ISS as an Analog for Future Space Expeditions
The ground-based and space analog studies have been instructive. However, the Mir missions and availability of a continuously occupied International Space Station since November 2000 made it possible to investigate the physical and behavioral issues associated with space exploration directly, under operational conditions, and with the participation of actual space crews. For example, Nick Kanas and his associates studied cultural differences, communications, and other interactions among Mir and ISS crews and between station and ground personnel using questionnaires and psychological mood scales; he found evidence of displacement of tension to ground personnel, cultural differences concerning work pressure, and importance of task and support leadership roles for group cohesion (Kanas et al. 2001; Kanas et al. 2007; Kanas 2012). Laura Barger and Charles Czeisler evaluated the influence of spaceflight on sleep and circadian rhythms and found alarming sleep deficits and use of sleeping pills among astronauts (Barger et al. 2014). Scott Dulchavsky and ISS crewmembers developed ultrasound procedures to diagnose on-orbit injuries and illnesses and assessed the feasibility of ultrasound for monitoring in-flight bone alterations (Chiao et al. 2005; Foale et al. 2005). Peter Cavanagh studied loads on the lower body and muscle activity in ISS crewmembers to better understand microgravity-induced bone and muscle loss (Cavanagh et al. 2010); it is important to note that the problem of bone demineralization, along with radiation loading and muscle atrophy, must be solved before humans can travel far from Earth (Stuster 2010a). Kritina Holden investigated the effects of vibration on visual performance during launch and reentry; and Laurence Harris identified the contributions of internal and external cues to self-orientation during and after exposure to microgravity. Hundreds of studies have been conducted onboard the ISS and the tempo of biomedical, human factors, and habitability research has increased with each new expedition.
Since the beginning of human space flight, engineers and mission planners have asked flight surgeons, psychologists, and psychiatrists about the relative importance of the various behavioral issues when planning operations and designing space craft. The response always has been that interpersonal relations among crew members is the most important issue, a belief shared by many, including science fiction writers, the general public, and especially those familiar with the history of exploration. However, behavioral scientists could only cite anecdotal evidence for the importance of “getting along with each other” and they could not provide a method for calculating how much more or less important any issue is than another. Planners and equipment designers are data-driven and need a metric to guide the allocation of scarce resources, but laboratory and space analog studies usually focus on a specific issue (e.g., sleep, communications), which makes it impossible to place the various influences on human behavior in order of importance to space crews. A content analysis of journals that were written by the leaders and physicians at French remote duty stations (in Antarctica and on small islands in the South Indian Ocean) provided the first quantitative data on which to base a rank-ordering of behavioral issues in terms of salience or importance (Stuster et al. 2000). That study identified 22 major categories of behavioral issues associated with living and working in isolation and confinement and placed the categories and constituent themes in order of priority based on the relative frequency of category assignments. The same method was employed, beginning in 2003, in a NASA flight experiment in which astronauts maintained confidential journals during their 6-month expeditions to the ISS. That 16-year study found adjustment to ISS conditions, work, group interaction, and outside communications to be the most frequent topics of astronauts’ journal entries. Many of the entries concerning work and communications with ground personnel addressed problems with the procedures provided to the crew and with inadequate time scheduled for task performance (Stuster 2010b, 2016). The latter issue emerged as the primary contributor to astronaut stress, a response predicted by Larry Palinkas from Antarctic data, as mentioned previously. The content analysis of astronaut journals confirmed the importance of sufficient sleep; food and eating together; and meaningful work and recreation opportunities. The study also detected a decline in morale during the third quarters of expeditions, regardless of duration. Astronauts requested continuation of the study, due largely to the benefits participants experienced by having a confidential outlet for frustrations that might jeopardize essential relationships if expressed directly.
Attention to psychosocial issues was a central concern of the most esteemed explorers of the past and has been identified as essential to the success of long duration space expeditions by all formal reviews of the subject since before the creation of NASA. It is particularly noteworthy that NASA’s Astronaut Corps, a group that originally denied the possibility of interpersonal and other behavioral problems, has acknowledged the importance of psychosocial issues, based largely on the recognition that they are heirs to a long tradition of exploration and the experiences of their colleagues onboard Mir and the International Space Station . At the time of this writing, astronauts are participating in a wide range of behavioral research while serving onboard the ISS, and NASA is planning additional studies to better understand the behavioral issues associated with long duration isolation and confinement, using ground-based and on-orbit analogs, in preparation for expedition-class missions to asteroids, Mars, and beyond.
- Barger LK, Flynn-Evans EE, Kubey A, Walsh L, Ronda JM, Wang W, Wright KP Jr, Czeisler CA (2014) Prevalence of sleep deficiency and use of hypnotic drugs in astronauts before, during, and after spaceflight: an observational study. Lancet Neurol. August 8; epubGoogle Scholar
- Basner M, Dinges DF, Mollicone DJ, Ecker AJ, Jones CW, Hyder EC, Di Antonio A, Savelev IE, Kan K, Goel N, Morukov BV, Sutton JP (2013) Mars 520-day mission simulation reveals protracted crew hypokinesis and alterations of sleep duration and timing. Proc Natl Acad Sci 110(7):2635–2640CrossRefGoogle Scholar
- Basner M, Dinges DF, Mollicone DJ, Ecker AJ, Jones CW, Hyder Di Antonio A, Savelev I E, Kan K, Goel, N, Morukov, B.V., Sutton, J.P. (2014) Psychological and behavioral changes during confinement in a 520-day simulated interplanetary mission to Mars. PLoS ONE 9(3): e93298. https://doi.org/10.1371Google Scholar
- Brady JV (1992) Continuously programmed environments and the experimental analysis of human behavior. Cambridge Center For Behavioral Studies, Cambridge, MAGoogle Scholar
- Connors MM, Harrison A, Akins FR (1985) Living aloft: human requirements for extended spaceflight. (NASA SP-483), National Aeronautics and Space Administration, Washington, DCGoogle Scholar
- Cousteau J-Y (1966) Working for weeks on the sea floor. Natl Geogr 129(4):498–537Google Scholar
- Dick SJ, Cowing K (eds) (2005) Risk and exploration: Earth, Sea, and the Stars. NASA History Division (NASA SP-2005-4701), Washington, DCGoogle Scholar
- Foale CM, Kaleri AY, Sargsyan AE, Sargsyan AE, Hamilton DR, Melton SL, Martin DS, Dulchavsky SA (2005) Diagnostic instrumentation aboard ISS: just in time training for non-physician crewmembers. Aviat Space Environ Med 76:594–598Google Scholar
- Gunderson EKE (1966) Adaptation to extreme environments: prediction of performance. Navy Neuropsychiatric Research Unit. Unit Report No. 66–17, San DiegoGoogle Scholar
- Gunderson EKE, Nelson PD (1963) Adaptation of small groups to extreme environments. Aerosp Med 34:1111–1115Google Scholar
- Gunderson EKE (1968) Psychiatric problems in polar environments. Navy Medical Neuropsychiatric Research Unit, San Diego. Unit Report No. 68-4Google Scholar
- Kanas N (2012) Human interactions on-orbit. Space technology library, Springer, SPTL vol 29, 2013: 93–106, 21Google Scholar
- Kanas N, Federson WE (1971) Behavioral, psychiatric, and sociological problems of long-duration space missions. NASA TM X-58067, HoustonGoogle Scholar
- Kanas N, Salnitskiy V, Boyd J, Gushin V, Weiss D, Saylor S, Kozerenko O, Marmar C (2007) Crewmember and mission control personnel interactions during International Space Station missions. Aviat Space Environ Med 78:601–607Google Scholar
- Kanas N, Salnitskiy V, Grund EM, Weiss DS, Gushin V, Bostrom A, Kozerenko O, Sled A, Marmar CR (2001) Psychological issues in space: results from Shuttle/Mir. Gravit Space Biol Bull 14(2):35–45Google Scholar
- Nansen F (1897) Farthest north, 2 vols. Harper & Brothers, New YorkGoogle Scholar
- Nelson PD (1962) Leadership in small isolated groups. Navy Medical Neuropsychiatric Research Unit, San Diego. Unit Report No. 62-13Google Scholar
- Nelson P (1965) Psychological aspects of Antarctic living. US Navy Neuropsychiatric Research Unit. Unit Report No. 64–28, San DiegoGoogle Scholar
- Nelson PD (1973) Indirect observation of groups. In: Rasmussen JE (ed) Man in isolation and confinement. Aldine Publishing Company, ChicagoGoogle Scholar
- Palinkas LA (2001) Psychosocial issues in long-term space flight: Overview. Gravit Space Biol Bull 14(2):25–33Google Scholar
- Radloff R, Helmreich R (1968) Groups under stress: psychological research in Sealab II. Appleton-Century-Crofts, New YorkGoogle Scholar
- Ryumin, V (1980) 175 days in space: a Russian cosmonaut’s private diary (trans: Gris H (ed)). Unpublished manuscriptGoogle Scholar
- Sells SB (1973) The taxonomy of man in enclosed space. In: Rasmussen JE (ed) Man in isolation and confinement. Aldine Publishing Company, ChicagoGoogle Scholar
- Spence JT, Helmreich R (1978) Masculinity and femininity: their psychological dimensions, correlates and antecedents. University of Texas Press, AustinGoogle Scholar
- Stuster, J (1986) Space station habitability recommendations based on a systematic somparative analysis of analogous conditions. NASA Contractor Report 3943, Ames Research CenterGoogle Scholar
- Stuster J (1996) Bold endeavors: lessons from polar and space exploration. Naval Institute Press, AnnapolisGoogle Scholar
- Stuster J, Bachelard C, Suedfeld P (2000) The relative importance of behavioral issues during long-duration I.C.E. missions. Aviat Space Environ Med 71(9):A17–A25Google Scholar
- Stuster J (2010a) Acceptable risk: the human mission to Mars. J Cosmol 12:3566–3577Google Scholar
- Stuster J (2010b) Behavioral issues associated with isolation and confinement: review and analysis of astronaut journals. National Aeronautics and Space Administration. NASA/TM-2010-216130 (July). Houston: Johnson Space CenterGoogle Scholar
- Stuster J (2016) Behavioral issues associated with isolation and confinement: Review and Analysis of Astronaut Journals, phase 2 final report. NASA Johnson Space Center, Houston. NASA/TM-2016-218603Google Scholar
- Taylor AJW (1978) Antarctica psychometrica unspectacular. N Z Antarct Rec 6:36–45Google Scholar
- Ushakov IB, Morukov BV, Bubeev YA, Gushin VI, Yu G, Vasil’eva AGV, Shved DM (2014) Main findings of psychophysical studies in the Mars 500 experiment. Her Russ Acad Sci 84(2):106–114. © Pleiades Publishing, Ltd. Original Russian Text published in Vestnik Rossiiskoi Akademii Nauk 84(3):212–221CrossRefGoogle Scholar