During the long way to Mars: effects of 520 days of confinement (Mars500) on the assessment of affective stimuli and stage alteration in mood and plasma hormone levels

Team Self-Maintenance during Long-Duration Space Exploration: A Conceptual Framework

OBJECTIVE

We developed a conceptual framework of Team Self-Maintenance (TSM) within long-duration space exploration (LDSE), which we define as the process of monitoring, adjusting, and maintaining the psychological well-being of a team in the absence of external support.

BACKGROUND

Specific to LDSE and isolated, confined, and extreme (ICE) environments, periods of routine can have a debilitating effect on the crew's well-being and performance, and TSM is a critical process for avoiding these detrimental effects.

METHOD

Based on themes drawn from nine subject matter expert interviews combined with an extensive literature review on related concepts, we developed an integrative conceptual framework of the key inputs, processes, and outputs involved in TSM within LDSE contexts.

RESULTS

Our TSM framework suggests team well-being as a key outcome that must be maintained during LDSE and information sharing, self-regulation, resource recovery, and emotional support as the key processes that enable team well-being. We also identify several contextual inputs that can serve as intervention points for enabling effective TSM.

CONCLUSION

Our framework suggests that future research and practice aimed at effective LDSE should emphasize team well-being, rather than just performance, and that there are many open questions in terms of how teams will manage their own socio-emotional needs (e.g., conflict, recovery activities, and boredom) without external systems and support.

APPLICATION

This conceptual framework describes the primary inputs, processes, and outcomes involved in the team self-maintenance process. This framework reflects context-specific theorizing most likely to be applicable only to LDSE contexts.

Confinement induces oxidative damage and synaptic dysfunction in mice

A confined environment is an enclosed area where entry or exit is highly restricted, which is a risk factor for a work crew's mental health. Previous studies have shown that a crew is more susceptible to developing anxiety or depression in a confined environment. However, the underlying mechanism by which negative emotion is induced by confinement is not fully understood. Hence, in this study, mice were retained in a tube to simulate short-term confinement. The mice exhibited depressive-like behavior. Additionally, the levels of H₂O₂ and malondialdehyde in the prefrontal cortex were significantly increased in the confinement group. Furthermore, a label-free quantitative proteomic strategy was applied to analyze the abundance of proteins in the prefrontal cortex of mice. A total of 71 proteins were considered differentially abundant proteins among 3,023 identified proteins. Two differentially abundant proteins, superoxide dismutase [Mn] and syntaxin-1A, were also validated by a parallel reaction monitoring assay. Strikingly, the differentially abundant proteins were highly enriched in the respiratory chain, oxidative phosphorylation, and the synaptic vesicle cycle, which might lead to oxidative damage and synaptic dysfunction. The results of this study provide valuable information to better understand the mechanisms of depressive-like behavior induced by confined environments.

Integrating bioinformatic strategies in spatial life science research

As space exploration programs progress, manned space missions will become more frequent and farther away from Earth, putting a greater emphasis on astronaut health. Through the collaborative efforts of researchers from various countries, the effect of the space environment factors on living systems is gradually being uncovered. Although a large number of interconnected research findings have been produced, their connection seems to be confused, and many unknown effects are left to be discovered. Simultaneously, several valuable data resources have emerged, accumulating data measuring biological effects in space that can be used to further investigate the unknown biological adaptations. In this review, the previous findings and their correlations are sorted out to facilitate the understanding of biological adaptations to space and the design of countermeasures. The biological effect measurement methods/data types are also organized to provide references for experimental design and data analysis. To aid deeper exploration of the data resources, we summarized common characteristics of the data generated from longitudinal experiments, outlined challenges or caveats in data analysis and provided corresponding solutions by recommending bioinformatics strategies and available models/tools.

Isolation and confinement due to the COVID-19 pandemic: Lessons for human spaceflight

BACKGROUND

Astronauts live and work in isolated, confined, extreme (ICE) environments that create both high stress and the need for high performance. The COVID-19 pandemic created ICE-like conditions across the globe by confining people to their homes under the ever-present threat of disease. Our goal is to understand the impact of prior experience in ICE on coping, using the pandemic as a pseudo space analog environment.

METHODS

We administered a survey three times with 7 days between administrations. A total of 82 participants completed all three survey sessions, and these participants were divided into three groups for analysis. The first group is those with prior experience in an ICE environment (n = 17; 7F/10 M), the second is those aged 30-55 with a master's or doctoral degree and without prior experience (n = 22; 10F/12 M), and the third is the general population (n = 43; 27F/16 M). Linear mixed models were used for statistical analysis of the results, given the unequal sample sizes.

RESULTS

The experienced group did not show healthier mental health scores than the astronaut-like group, but both groups displayed higher scores than the general population. However, work productivity scores for the experienced group were higher on average than the other two groups.

DISCUSSION

Results suggest that prior experience in ICE may improve the capability to maintain productivity-corresponding to the idea of resilience. However, experience may not improve mental health maintenance, suggesting that other approaches are needed to prepare astronauts for the mental health stressors of long-duration exploration missions.

Defining the resilience of the human salivary microbiota by a 520-day longitudinal study in a confined environment: the Mars500 mission

BACKGROUND

The human microbiota plays several roles in health and disease but is often difficult to determine which part is in intimate relationships with the host vs. the occasional presence. During the Mars500 mission, six crewmembers lived completely isolated from the outer world for 520 days following standardized diet regimes. The mission constitutes the first spaceflight simulation to Mars and was a unique experiment to determine, in a longitudinal study design, the composition and importance of the resident vs. a more variable microbiota-the fraction of the human microbiota that changes in time and according to environmental conditions-in humans.

METHODS

Here, we report the characterization of the salivary microbiota from 88 samples taken during and after Mars500 mission for a total of 720 days. Amplicon sequencing of the V3-V4 regions of 16S rRNA gene was performed, and results were analyzed monitoring the diversity of the microbiota while evaluating the effect of the three main variables present in the experimental system: time, diet, and individuality of each subject.

RESULTS

Results showed statistically significant effects for either time, diet, and individuality of each subject. The main contribution came from the individuality of each subject, emphasizing salivary microbiota-personalized features, and an individual-based resilience of the microbiota.

CONCLUSIONS

The uniqueness of Mars500 mission, allowed to dampen the effect of environmental variables on salivary microbiota, highlighting its pronounced personalization even after sharing the same physical space for more than a year. Video abstract.

How Experiences Affect Psychological Responses During Supervised Fasting: A Preliminary Study

As an unusual event, fasting can induce strong physiological and psychological reactions, but there is still no clear understanding of how previous fasting experiences affect people’s responses to current fasting. This study aimed to investigate the influence of previous fasting experiences on participants’ basic physiological and psychological responses in a fasting experiment conducted under intensive medical monitoring. For a 22-day experiment divided into four phases (3-day Baseline; 10-day Complete Fasting; 4-day Calorie Restriction; and 5-day Recovery phases), a total of 13 persons participated; the participants were divided into a group with prior fasting experience (Experienced: N = 6) and a group without prior fasting experience (Newbie: N = 7). The results indicate no group differences in physiological responses (i.e., weight, glucose, and ketone bodies); however, differences in psychological states were observed, with the Newbie group showing more negative psychological states overall throughout the experiment (i.e., greater appetite, more negative mood states, more stress, less vitality, and fewer recovery resources). Hence, previous fasting experience may be a buffer against negative feelings during current fasting. For this reason, it is important to consider fasting experiences as a vital factor in future research.

A GABAergic neural circuit in the ventromedial hypothalamus mediates chronic stress-induced bone loss

Homeostasis of bone metabolism is regulated by the central nervous system, and mood disorders such as anxiety are associated with bone metabolism abnormalities, yet our understanding of the central neural circuits regulating bone metabolism is limited. Here, we demonstrate that chronic stress in crewmembers resulted in decreased bone density and elevated anxiety in an isolated habitat mimicking a space station. We then used a mouse model to demonstrate that GABAergic neural circuitry in the ventromedial hypothalamus (VMH) mediates chronic stress-induced bone loss. We show that GABAergic inputs in the dorsomedial VMH arise from a specific group of somatostatin neurons in the posterior region of the bed nucleus of the stria terminalis, which is indispensable for stress-induced bone loss and is able to trigger bone loss in the absence of stressors. In addition, the sympathetic system and glutamatergic neurons in the nucleus tractus solitarius were employed to regulate stress-induced bone loss. Our study has therefore identified the central neural mechanism by which chronic stress-induced mood disorders, such as anxiety, influence bone metabolism.

Human Adaptations to Multiday Saturation on NASA NEEMO

Human adaptation to extreme environments has been explored for over a century to understand human psychology, integrated physiology, comparative pathologies, and exploratory potential. It has been demonstrated that these environments can provide multiple external stimuli and stressors, which are sufficient to disrupt internal homeostasis and induce adaptation processes. Multiday hyperbaric and/or saturated (HBS) environments represent the most understudied of environmental extremes due to inherent experimental, analytical, technical, temporal, and safety limitations. National Aeronautic Space Agency (NASA) Extreme Environment Mission Operation (NEEMO) is a space-flight analog mission conducted within Florida International University’s Aquarius Undersea Research Laboratory (AURL), the only existing operational and habitable undersea saturated environment. To investigate human objective and subjective adaptations to multiday HBS, we evaluated aquanauts living at saturation for 9–10 days via NASA NEEMO 22 and 23, across psychologic, cardiac, respiratory, autonomic, thermic, hemodynamic, sleep, and body composition parameters. We found that aquanauts exposed to saturation over 9–10 days experienced intrapersonal physical and mental burden, sustained good mood and work satisfaction, decreased heart and respiratory rates, increased parasympathetic and reduced sympathetic modulation, lower cerebral blood flow velocity, intact cerebral autoregulation and maintenance of baroreflex functionality, as well as losses in systemic bodyweight and adipose tissue. Together, these findings illustrate novel insights into human adaptation across multiple body systems in response to multiday hyperbaric saturation.

Personalized Epigenome Remodeling Under Biochemical and Psychological Changes During Long-Term Isolation Environment

It has been reported that several aspects of human health could be disturbed during a long-term isolated environment (for instance, the Mars-500 mission), including psychiatric disorders, circadian disruption, temporal dynamics of gut microbiota, immune responses, and physical-activity-related neuromuscular performance. Nevertheless, the mechanisms underlying these disturbances and the interactions among different aspects of human adaptation to extreme environments remain to be elucidated. Epigenetic features, like DNA methylation, might be a linking mechanism that explains the involvement of environmental factors between the human genome and the outcome of health. We conducted an exploration of personalized longitudinal DNA methylation patterns of the peripheral whole blood cells, profiling six subjects across six sampling points in the Mars-500 mission. Specifically, we developed a Personalized Epigenetic-Phenotype Synchronization Analysis (PeSa) algorithm to explore glucose- and mood-state-synchronized DNA methylation sites, focusing on finding the dynamic associations between epigenetic patterns and phenotypes in each individual, and exploring the underling epigenetic connections between glucose and mood-state disturbance. Results showed that DMPs (differentially methylated-probes) were significantly enriched in pathways related to glucose metabolism (Type II diabetes mellitus pathway), mood state (Long-term depression) and circadian rhythm (Circadian entrainment pathway) during the mission. Furthermore, our data revealed individualized glucose-synchronized and mood-state-synchronized DNA methylation sites, and PTPRN2 was found to be associated with both glucose and mood state disturbances across all six subjects. Our findings suggest that personalized phenotype-synchronized epigenetic features could reflect the effects on the human body, including the disturbances of glucose and mood-states. The association analysis of DNA methylation and phenotypes, like the PeSa analysis, could provide new possibilities in understanding the intrinsic relationship between phenotypic changes of the human body adapting to long-term isolation environmental factors.

Multi-System Adaptation to Confinement During the 180-Day Controlled Ecological Life Support System (CELSS) Experiment

Confinement experiments are essential to prepare long-term space exploration. The 180-day Chinese CELSS (Controlled Ecological Life Support System) study is unique in its design, including a closed-loop system and mid-mission simulation of Mars-like day-night cycle of 24 h 40 min for 36 days (days 72-108). Our aim was to study physiological and psychological consequences of this confinement in four healthy volunteers (one female). CELSS platform consisted of six interconnected modules including four greenhouses. Life support systems were controlled automatically. Body composition, fluid compartments, metabolic state, heart, large vessels, endothelial function, and muscle tone were studied using biological, functional, and/or morphological measurements. Behavioral activities were studied by ethological monitoring; psychological state was assessed by questionnaires. Body weight decreased by ∼2 kg mostly due to lean mass loss. Plasma volume and volume-regulating hormones were mostly stable. Carotid intima-media thickness (IMT) increased by 10-15%. Endothelium-dependent vasodilation decreased. Masseter tone increased by 6-14% suggesting stress, whereas paravertebral muscle tone diminished by 10 ± 6%. Behavioral flow reflecting global activity decreased 1.5- to 2-fold after the first month. Psychological questionnaires revealed decrease in hostility and negative emotions but increase in emotional adaptation suggesting boredom and monotony. One subject was clearly different with lower fitness, higher levels of stress and anxiety, and somatic signs as back pain, peak in masseter tone, increased blood cortisol and C-reactive protein. Comparison of CELSS experiment with Mars500 confinement program suggests the need for countermeasures to prevent increased IMT and endothelial deconditioning. Daily activity in greenhouse could act as countermeasure against psycho-physiological deconditioning.

What We Know About Team Dynamics for Long-Distance Space Missions: A Systematic Review of Analog Research

Background: To anticipate the dynamics of future long-distance space exploration mission (LDSEM) teams, research is conducted in analog environments (e.g., Antarctic expeditions, space chamber simulations), or environments that share key contextual features of LDSEM such as isolation and confinement. We conducted a systematic review of research conducted on teams in LDSEM-analog environments to identify which factors have been examined with quantitative research, and to summarize what the studies reveal about team dynamics in LDSEM-analog environments. Methods: We used a comprehensive search strategy to identify research on teams that lived and worked together. Data on team dynamics were extracted where possible, and sources were coded for key contextual features. The data did not lend themselves to traditional meta-analysis. We used two approaches to summarize the data: a weighted averages approach when the study reported enough data to calculate an effect size, and descriptive figures when data across studies were directly comparable. Results: Seventy-two sources met our inclusion criteria, yielding 253 effect sizes and 1,150 data points. Results from our weighted averages approach suggested that the team cohesion and performance relationship may be operating differently in isolated and confined environments than other teams that lived and worked together (e.g., military teams), and that, given the available data, we can say very little about the magnitude and direction of the relationship. Our descriptive figures revealed important trends: (a) team members in longer missions generally spent less social time together than shorter missions; (b) consistent team efficiency over time was typical, whereas decreased team efficiency over time was atypical; (c) by 40% of mission completion or 90 days, all teams reported at least one conflict, (d) commanders' written communication with mission control decreased in length over time, and (e) team mood dynamics did not consistently support the third-quarter phenomenon. Conclusions: There are inherent limitations to our study, given the nature of the analog research (e.g., correlational studies, small sample size). Even so, our systematic review provides key insights into team dynamics in LDSEM-analog environments. We discuss the implications of our research for managing future space crews. Importantly, we also provide guidance for future research.

Body composition and metabolic changes during a 520-day mission simulation to Mars

PURPOSE

The "Mars-500 project" allowed to evaluate the changes in psychological/physiological adaptation over a prolonged confinement, in order to gather information for future missions. Here, we evaluated the impact of confinement and isolation on body composition, glucose metabolism/insulin resistance and adipokine levels.

METHODS

The "Mars-500 project" consisted of 520 consecutive days of confinement from June 3, 2010 to Nov 4, 2011. The crew was composed of six male subjects (three Russians, two Europeans, and one Chinese) with a median age of 31 years (range 27-38 years).

RESULTS

During the 520-day confinement, total body mass and BMI progressively decreased, reaching a significant difference at the end (417 days) of the observation period (- 9.2 and - 5.5%, respectively). Fat mass remained unchanged. A progressive and significant increase of fasting plasma glucose was observed between 249 and 417 days (+ 10/+ 17% vs baseline), with a further increase at the end of confinement (up to + 30%). Median plasma insulin showed a non-significant early increment (60 days; + 86%). Total adiponectin halved (- 47%) 60 days after hatch closure, remaining at this nadir (- 51%) level for a further 60 days. High molecular weight adiponectin remained significantly lower from 60 to 168 days.

CONCLUSIONS

Based on these data, countermeasures may be envisioned to balance the potentially harmful effects of prolonged confinement, including a better exercise program, with accurate monitoring of (1) the individual activity and (2) the relationship between body composition and metabolic derangement.

Evaluation of psychological stress in confined environments using salivary, skin, and facial image parameters

Detecting the influence of psychological stress is particularly important in prolonged space missions. In this study, we determined potential markers of psychological stress in a confined environment. We examined 23 Japanese subjects staying for 2 weeks in a confined facility at Tsukuba Space Center, measuring salivary, skin, and facial image parameters. Saliva was collected at four points in a single day to detect diurnal variation. Increases in salivary cortisol were detected after waking up on the 4th and 11th days, and at 15:30 on the 1st and in the second half of the stay. Transepidermal water loss (TEWL) and sebum content of the skin were higher compared with outside the facility on the 4th and 1st days respectively. Increased IL-1β in the stripped stratum corneum was observed on the 14th day, and 7 days after leaving. Differences in facial expression symmetry at the time of facial expression changes were observed on 11th and 14th days. Thus, we detected a transition of psychological stress using salivary cortisol profiles and skin physiological parameters. The results also suggested that IL-1β in the stripped stratum corneum and facial expression symmetry are possible novel markers for conveniently detecting psychological stress.

Temporal dynamics of the gut microbiota in people sharing a confined environment, a 520-day ground-based space simulation, MARS500

BACKGROUND

The intestinal microbial communities and their temporal dynamics are gaining increasing interest due to the significant implications for human health. Recent studies have shown the dynamic behavior of the gut microbiota in free-living, healthy persons. To date, it is not known whether these dynamics are applicable during prolonged life sharing in a confined and controlled environment.

RESULTS

The MARS500 project, the longest ground-based space simulation ever, provided us with a unique opportunity to trace the crew microbiota over 520 days of isolated confinement, such as that faced by astronauts in real long-term interplanetary space flights, and after returning to regular life, for a total of 2 years. According to our data, even under the strictly controlled conditions of an enclosed environment, the human gut microbiota is inherently dynamic, capable of shifting between different steady states, typically with rearrangements of autochthonous members. Notwithstanding a strong individuality in the overall gut microbiota trajectory, some key microbial components showed conserved temporal dynamics, with potential implications for the maintenance of a health-promoting, mutualistic microbiota configuration.

CONCLUSIONS

Sharing life in a confined habitat does not affect the resilience of the individual gut microbial ecosystem, even in the long term. However, the temporal dynamics of certain microbiota components should be monitored when programming future mission simulations and real space flights, to prevent breakdowns in the metabolic and immunological homeostasis of the crewmembers.

Reductions in circulating endocannabinoid 2-arachidonoylglycerol levels in healthy human subjects exposed to chronic stressors

Increasing evidence indicates that chronic stress, such as social isolation, plays an important role in the development of a variety of psychiatric and somatic disorders. Meanwhile, chronic stress imposed by prolonged isolation and confinement in the spacecraft is also one of the major concerns for the health of future interplanetary space travelers. Preclinical studies suggest that the peripheral endocannabinoid (eCB) system is involved in the regulation of the stress response and eCB signaling is implicated in the pathogenesis of stress-related diseases. However, there are only few human studies addressing this topic, of which most focusing on patients who have already developed a certain type of disorder. It remains unknown whether chronic stress may affect eCB signaling in healthy humans. A 520-d isolation and confinement study simulating a flight to Mars provided an extraordinary chance to study the effects of prolonged stress in healthy humans. During the study period, the participants lived in confinement and could not meet their families, friends, or strangers for more than 500 days. We examined the impact of chronic exposure to isolation and confinement through monitoring their psychological state, brain cortical activity, sympathetic adrenal-medullary system response and eCB signaling response. We observed reduced positive emotion ratings, decreased brain cortical activities and high levels of catecholamine release, indicating that prolonged exposure to isolation and confinement stressors may bring about changes both psychologically and physiologically. Importantly, for eCB signaling response, blood concentrations of eCB 2-arachidonoylglycerol (2-AG), but not anandamide (AEA), were significantly reduced (p<0.001), suggesting that dysregulation of 2-AG signaling might be specifically implicated in the response to chronic stressors.

Existential risks: exploring a robust risk reduction strategy

A small but growing number of studies have aimed to understand, assess and reduce existential risks, or risks that threaten the continued existence of mankind. However, most attention has been focused on known and tangible risks. This paper proposes a heuristic for reducing the risk of black swan extinction events. These events are, as the name suggests, stochastic and unforeseen when they happen. Decision theory based on a fixed model of possible outcomes cannot properly deal with this kind of event. Neither can probabilistic risk analysis. This paper will argue that the approach that is referred to as engineering safety could be applied to reducing the risk from black swan extinction events. It will also propose a conceptual sketch of how such a strategy may be implemented: isolated, self-sufficient, and continuously manned underground refuges. Some characteristics of such refuges are also described, in particular the psychosocial aspects. Furthermore, it is argued that this implementation of the engineering safety strategy safety barriers would be effective and plausible and could reduce the risk of an extinction event in a wide range of possible (known and unknown) scenarios. Considering the staggering opportunity cost of an existential catastrophe, such strategies ought to be explored more vigorously.