Team dynamics in space missions.

There has been consistent recognition that team dynamics play a critical role in determining the success of space missions, particularly given the extreme psychological and operational demands of isolated, confined, and autonomous environments. Bell et al. [16] provide one of the most comprehensive assessments of this topic, emphasizing that team composition is not only about individual competence but also about the configuration of interpersonal compatibility that influences both social integration and team performance. Their review identifies two major pathways through which composition affects mission outcomes: (1) by shaping the quality of interpersonal relations such as cohesion, conflict, and subgroup formation and (2) by affecting critical team processes such as coordination, shared cognition, and adaptability. The report also highlights that both surface-level (e.g., age, sex, culture) and deep-level attributes (e.g., personality traits, values, dominance) can lead to dysfunction when not aligned or managed, particularly in environments requiring high interdependence and limited external support. These insights underscore the importance of proactive team design and compatibility assessments in spaceflight planning.

Cohesion defined as the strength of social bonds and shared commitment among crew members has emerged as a core factor in mission stability. Rather than a static trait, it evolves over time and is shaped by interpersonal compatibility, communication style, and group adaptation. Analog missions such as Mars-500 and HI-SEAS have shown that cohesion tends to decline or fluctuate during periods of stress, especially mid-mission [17,18]. These cohesion patterns reflect how interpersonal dynamics adapt under isolation and stress, emphasizing that team composition directly influences the crew’s psychological resilience [16].

Research on the ISS missions has also revealed the psychological challenges faced by astronauts in prolonged spaceflight. Kanas et al. [7] conducted studies involving surveys of astronauts and cosmonauts during and after missions to assess interpersonal relations and psychological well-being. Results indicated that interpersonal tensions, such as misunderstandings and conflicts, were common and could negatively impact crew morale and performance. The importance of effective communication, cultural understanding, and conflict resolution skills was emphasized as crucial in mitigating these issues.

Similarly, during the Mir space station missions, crew members experienced significant interpersonal stress. A notable incident involved a serious conflict between Russian cosmonauts and a visiting astronaut, leading to communication breakdowns and operational inefficiencies [19]. These events underscored the challenges of multicultural crews and the potential for conflicts arising from cultural differences.

Mars analog missions, such as the Mars-500 project and the HI-SEAS, have provided valuable insights into team dynamics during long-duration isolation [17,18]. In the Mars-500 project, six crew members were confined for 520 days to simulate a mission to Mars. Researchers observed that over time, the crew experienced declines in mood, increased interpersonal tension, and reduced motivation. Notably, cohesion fluctuated, with periods of increased conflict, especially during the mid mission phase [17]. In the HI-SEAS missions, crews lived in a dome on a remote volcanic site in Hawai’i for periods ranging from four to twelve months. Analyses revealed that crew cohesion and individual well-being were significantly influenced by personality compatibility and communication styles [18]. Effective leadership and clear communication were identified as critical factors in maintaining team harmony.

Antarctic expeditions serve as terrestrial analogs for space missions due to their extreme environments and isolation. Studies have documented phenomena such as the “third-quarter phenomenon,” where psychological distress peaks during the middle of the mission [20]. Interpersonal conflicts, mood disturbances, and declines in cognitive function have been reported, emphasizing the need for psychological support and team-building interventions [21].

Recent contributions from organizational and communication sciences have emphasized the importance of conceptualizing spaceflight teams not merely as cohesive units, but as adaptive systems embedded within evolving task environments. Lungeanu et al. [14] adopt a task management perspective to analyze multiteam systems in spaceflight, revealing how coordination patterns shift under conditions of increasing crew autonomy, temporal pressure, and dynamic operational priorities. Their findings underscore the need to understand how team structures evolve as astronauts assume responsibilities traditionally managed by Earth-based support. Building on this, Antone et al. [22] highlight the value of computational approaches to examine how individual differences, such as personality traits, interact with team composition and influence performance over time. They call for integrative frameworks capable of capturing nonlinear, time-sensitive team processes. Similarly, Mesmer-Magnus et al. [15] identify key complexities unique to spaceflight teams including delayed communication, adaptive role shifts, and cumulative psychological stressors and advocate for a new generation of theoretical and modeling tools to guide crew design and intervention strategies. Together, these perspectives provide a conceptual foundation for exploring more dynamic and empirically grounded representations of team functioning in spaceflight.

1.1.1 Psychological adaptation in extreme environments.

Understanding psychological adaptation and team dynamics in extreme environments is essential for improving crew performance and mission success. The confined and isolated settings of space missions pose unique psychological challenges that require comprehensive strategies to address. Researchers have explored various theoretical frameworks to explain how individuals and teams cope with the stressors inherent in such settings, integrating these perspectives with empirical findings from space missions and analog environments.

Environmental psychology examines the interplay between individuals and their physical surroundings, focusing on how confinement, isolation, and sensory deprivation impact psychological well-being and interpersonal relations. Environmental and situational factors, such as limited space, lack of privacy, and monotonous surroundings, can affect mood and behavior [5]. Designing habitats that consider human factors and provide opportunities for recreation and personal space can improve psychological well-being. Incorporating elements that simulate natural environments, providing varied lighting conditions, and ensuring ergonomic design can alleviate some of the stress associated with long-term confinement [23].

Cognitive strategies and coping mechanisms play a crucial role in managing stress in these environments. Individuals employ various cognitive strategies to handle stress, such as positive reinterpretation, problem-solving, and acceptance [24]. Effective coping mechanisms enhance psychological resilience, allowing crew members to maintain performance under stress. Teams that foster adaptive coping can mitigate the adverse effects of isolation and confinement. Access to psychological support, both through pre-mission training and during the mission, helps in managing stress and maintaining mental health [7]. Interventions may include stress management techniques, counseling resources, and promoting social support within the team. Regular psychological assessments can identify issues early, allowing for timely interventions [21].

Cultural and language differences may pose additional challenges in multicultural crews. Language barriers and differing cultural norms can lead to misunderstandings and conflicts [25,26]. Emphasizing cultural competence, inclusive practices, and mutual respect can mitigate these issues and enhance team cohesion. Crew selection processes can focus on identifying individuals with compatible personality traits and strong coping abilities to reduce the likelihood of conflicts and improve overall team functioning [27]. Pre-mission training that includes communication skills, cultural awareness, and language skills can prepare crew members for the diversity they will encounter [28].

Communication patterns are closely linked to team cohesion and performance. Effective communication, characterized by regular and open exchanges, can prevent misunderstandings and build trust among crew members [29,30]. Establishing clear communication protocols, utilizing reliable communication technologies, and promoting active listening are essential for mission success.

Leadership style and clarity of roles within the team significantly impact team dynamics. Participative leadership and well-defined roles have been associated with higher team effectiveness [18]. Leaders who are adaptable, culturally sensitive, and supportive can positively influence team morale and performance. Clear role definitions ensure that each team member understands their responsibilities, reducing ambiguity and potential conflicts.

The integration of theoretical perspectives with practical applications is essential for the development of strategies aimed at enhancing team dynamics. Considerations related to environmental design such as the inclusion of private spaces, recreational facilities, and aesthetically pleasing elements can significantly reduce the adverse effects of confinement and monotony [23]. Furthermore, the provision of continuous psychological support throughout the duration of the mission is critical for sustaining mental health and promoting team cohesion [21].

1.1.2 Personality traits.

A key factor in team dynamics and performance are personality traits, especially in high-stress and isolated environments like space missions. These traits fundamentally shape how individuals perceive and respond to prolonged stress, confinement, and interpersonal friction conditions that cannot be fully mitigated through training alone. In such extreme environments, where support from Earth is delayed and crews must operate autonomously, personality driven behaviors like emotional regulation, adaptability, and social sensitivity become critical for maintaining cohesion and operational stability [7,31]. The FFM, also known as the Big Five personality traits Openness to Experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism provides a comprehensive framework for understanding individual differences [8]. It enables mission planners to anticipate stress responses, communication dynamics, and interpersonal compatibility, offering predictive value for selecting and supporting crews capable of sustaining long-duration missions [33].

1. Conscientiousness: Associated with reliability, responsibility, and a strong work ethic. Barrick and Mount [34] found that conscientiousness positively correlates with job performance across various occupations, including teamwork settings.
2. Agreeableness: Linked to cooperation, compassion, and good naturedness. High agreeableness in team members correlates with better interpersonal relations and reduced conflict [35].
3. Neuroticism: Indicates emotional instability and anxiety. Individuals high in neuroticism may be more susceptible to stress and negatively impact team morale [36].
4. Extraversion: Characterized by sociability and assertiveness. Extraverts can contribute to positive team interactions but may dominate discussions if not balanced [37,38].
5. Openness to Experience: Involves creativity and adaptability. Teams with members high in openness may excel in problem-solving and adapting to new situations [39].

Musson et al. [31] examined the personality profiles of astronauts and found that successful crew members often scored high in conscientiousness and agreeableness, and low in neuroticism. These traits contributed to better stress management and interpersonal relations during missions. Kanas [19] emphasized the importance of selecting crew members with compatible personalities to minimize conflicts and enhance team cohesion. They noted that individual differences in coping styles and stress responses can significantly affect team dynamics.

Research has investigated how the composition of personality traits within a team affects performance. Peeters et al. [38] found that teams with lower variability in conscientiousness and agreeableness performed better due to shared work values and cooperative behaviors. Conversely, diversity in certain traits like openness can enhance creativity and problem-solving. A balance between homogeneity in traits that promote cohesion and diversity in traits that foster innovation is suggested to optimize team performance [40]. In addition to psychological factors, several studies point to the operational importance of skill diversity in spaceflight teams. For example, Sandal et al. [17] found in a 105-day space simulation that mismatches in functional responsibilities could create stress and inefficiencies, while balanced specialization improved perceived compatibility. Bishop et al. [18] likewise emphasized that clear differentiation of tasks and expertise supported stable performance in simulated long-duration crews. More broadly, reviews of team research in space and analog environments argue that composition must be understood across multiple dimensions, including both psychological compatibility and functional specialization [15]. However, most computational studies of spaceflight teams continue to model only one of these forms of heterogeneity at a time, leaving open questions about how personality diversity and role allocation interact in shaping stress, cohesion, and performance.

Traditional empirical and analog studies have provided valuable insights into stress, adaptation, and personality in spaceflight, but they remain limited in scope. Most capture only short durations or isolated factors, making it difficult to study the nonlinear and cumulative dynamics of multi-year missions [7,9]. Moreover, they cannot easily integrate individual heterogeneity (e.g., stable personality traits) and system-level processes (e.g., feedback loops between stress, cohesion, and performance). Computational modeling approaches provide a way to address these challenges by enabling controlled, repeatable experiments on complex social systems [41]. In particular, Agent-Based Modeling (ABM) offers a framework for linking micro-level variation among individuals to emergent team-level outcomes across time. Building on these limitations, the next section considers how ABM has been applied to study team dynamics and performance in spaceflight and other extreme environments.

1.1.3 ABM for investigating team dynamics and performance.

ABM is a computational methodology that simulates the actions, interactions, and decision-making processes of autonomous agents within a defined environment. These agents representing individuals, groups, or organizations are endowed with distinct attributes and behavioral rules [41,42]. By allowing agents to interact according to relatively simple local rules, ABM can yield complex, emergent patterns at the system level that may not be deducible from the characteristics of any single agent [43]. ABM provides a bottom-up approach to understanding how collective phenomena arise from individual actions. A major strength of ABM lies in its capacity to incorporate heterogeneity at the individual level. Since each agent can be assigned unique traits, preferences, and rules of interaction, it is possible to capture nuanced variations in behaviors and responses across a population. Through iterative simulations, ABM enables researchers to examine how differences in agent attributes influence emergent dynamics, revealing patterns not readily discerned using more traditional analytical or equation based modeling techniques. Applications have spanned a variety of domains ranging from crowd behavior and social network analysis to market trends and information diffusion demonstrating ABM’s flexibility and utility for understanding complex, adaptive systems [44].

Beyond broad social or economic systems, ABM has proven valuable in examining the internal dynamics of teams and workgroups, particularly when individual differences and personality traits are significant factors. By modeling agents as team members with distinct cognitive capabilities, communication patterns, or motivational profiles, ABM allows researchers to explore how these differences shape overall group outcomes.

Van Veen [45] applied ABM to study how various information aggregation mechanisms influence group decision-making. Agents were equipped with human-like reasoning abilities and exposed to different communication strategies, cognitive constraints, and levels of informational diversity. The findings revealed that approaches encouraging comprehensive information sharing such as random information dissemination and instructed dissent substantially improved decision quality. This underscores the importance of communication protocols and information flow in steering teams toward more effective outcomes.

In another study, Bergner et al. [46] used ABM to investigate how individual cognitive and noncognitive traits such as talkativeness, agreeableness, and critical thinking affected team performance. Their simulations showed that teams with higher average agreeableness and talkativeness achieved greater consensus and demonstrated improved collective performance. Although an increase in critical thinking initially reduced consensus, it still contributed modestly to performance improvements. These results highlight the delicate balance between fostering agreeable, communicative team environments and encouraging critical, rigorous thinking.

Perišić [47] further illustrated ABM’s capacity to evaluate how diversity in cognitive processes and interaction styles supports team adaptation. In simulating product development teams facing evolving challenges, the study found that more cognitively diverse teams were better at learning, adjusting strategies, and sustaining performance under changing conditions. Such insights emphasize the inherent value of cultivating a variety of cognitive profiles and communication behaviors within teams to enhance resilience and flexibility.

1.1.4 Applying ABM to long-duration space missions.

The complexity of long-duration space missions poses unique challenges for both individual crew members and the team as a whole. Factors such as prolonged isolation, confined habitats, communication delays, and psychological stressors demand robust analytical frameworks capable of capturing the intricate interplay between environmental conditions, individual personality traits, and collective behaviors. Among the available computational approaches, ABM has become a practical tool for examining how team processes unfold under spaceflight conditions. Rather than claiming to replace operational planning, these models offer structured experiments that reveal how differences in individual traits, coping styles, and interaction rules can accumulate into patterns at the team level. The value of this work lies in providing a systematic evidence base complementary to analog studies that helps mission planners and researchers anticipate potential risks and evaluate strategies to support crews. In this sense, ABM contributes not as a stand-alone decision system but as an analytic lens that extends what can be learned from empirical studies of long-duration missions [22,48].

In the context of space exploration, computational simulations have been employed to study various mission-critical factors. Parisi et al. [49] simulated anomalies observed in ISS and Apollo missions, focusing on how communication delays influence decision-making processes in Mars-like conditions. Their results revealed that signal latency can disrupt ground-crew coordination and shift tactical responsibilities toward the crew, thereby impacting team cohesion, stress management, and mission performance.

Mohanty et al. [50] examined how habitat design affects well-being and performance by simulating different spatial configurations and internal layouts. Their work highlighted how design features such as spatial arrangement, privacy levels, and resource allocation can either mitigate or exacerbate interpersonal tensions and stress, ultimately influencing team morale and efficiency.

Similarly, Orasanu et al. [51] investigated the relationship between individual stress responses and team performance in isolated, high-risk environments. Integrating physiological and psychological stress models into their simulations allowed them to demonstrate how variability in stress tolerance shaped in part by personality traits and physiological indicators directly affects group cohesion, communication, and operational efficiency. Such findings underscore the importance of identifying stress indicators and implementing countermeasures, such as targeted training and support systems, to maintain team health and high performance levels during extended missions.

While ABM offers significant advantages in modeling complex human systems, it is not without limitations. Current simulations often focus on a limited set of variables or shorter timeframes and may lack comprehensive psychological frameworks that consider the long-term evolution of personality traits, cultural factors, and dynamic coping mechanisms. As research progresses, incorporating these additional dimensions alongside improved calibration against empirical data can enhance the predictive accuracy and reliability of ABM. Ultimately, refining these models will better prepare astronauts and mission planners to anticipate psychological and social challenges, thus supporting sustained team effectiveness during the most demanding exploration endeavors.

2.4.1 Modeling stress and performance.

Agents’ stress and performance levels are dynamically updated at each simulation step based on individual factors, team interactions, and mission events. The modeling approach integrates psychological theories and empirical findings relevant to long-duration missions. Understanding the stress-performance relationship is crucial for comprehending how astronauts cope with mission demands.

Stress is modeled as a cumulative measure, influenced by various factors that represent distinct sources of stress for each agent. These components include task-related stress, social interactions, personality traits, environmental conditions, and fatigue due to workload and sleep deprivation.

The Personality Factor (PF_i) accounts for individual susceptibility to stress, influenced by neuroticism (N_i) and conscientiousness C_i. Agents with higher neuroticism experience greater stress, while higher conscientiousness mitigates stress. The personality factor is given by:

(1)

This factor serves as a baseline modifier for the overall stress level, reflecting the inherent psychological resilience or vulnerability of each agent [57].

Event stress (ES_i) captures stress due to task demands. It is calculated as the ratio of the number of tasks assigned to an agent (NT_i) to the average number of tasks across all agents :

(2)

This metric reflects the cognitive and workload pressures experienced by agents as they complete mission-critical tasks [60,61].

Time pressure (TP_i) represents stress caused by time constraints. It is defined as the ratio of the time required for tasks assigned to an agent to the total available working time :

(3)

Higher time pressure indicates a lack of sufficient time to complete tasks, leading to increased stress [62].

Social stress (SS_i) results from social interactions within the team. This stress is influenced by conflict levels (CL_i), social support units (SSU_i), and agreeableness (A_i). The equation for social stress is:

(4)

Agents with higher agreeableness and greater social support experience reduced social stress, while conflict increases stress levels [63,64,70].

Environmental Stress reflects stress induced by the environmental conditions of the mission, such as habitat constraints and external threats. It is modeled as a constant value with minor fluctuations, representing relatively stable yet persistent environmental challenges:

(5)

This reflects the assumption that stress from environmental factors, such as confinement, isolation, and monotony, remains relatively stable over time with minor fluctuations. Research has shown that in environments like space habitats or Antarctic stations, individuals often adapt to persistent environmental stressors, leading to a consistent level of stress [4].

Agents’ sleep hours, represented as Sleep Hours (SH_i), are adjusted dynamically based on stress levels. Higher stress leads to reduced sleep quality and duration. The equation for sleep hours ensures that sleep does not fall below a minimum operational limit of 4 hours:

(6)

This adjustment reflects the impact of stress on agents’ ability to recover from fatigue [71,72].

Effective Fatigue (EF_i) is derived from sleep deprivation and cumulative workload. It is calculated as:

(7)

where (CW_i) represents the cumulative workload of the agent. Effective fatigue quantifies the physical and cognitive exhaustion resulting from sustained work under stress [60,66].

The Overall Stress (S_i) level combines all these factors, weighted according to their relative importance. The equation is:

(8)

The weights sum to 1, ensuring a balanced contribution of stress components. The overall stress level is clamped between 0 and 1 to maintain validity [60,61].

Performance (P_i) is modeled as a function of stress, following the Yerkes-Dodson law. Performance peaks at an optimal stress level and decreases as stress deviates from this point:

(9)

Here, determines the sensitivity of performance to stress deviations, and the relationship captures the trade-off between stress and efficiency [67,68].

Team dynamics are also influenced by Team Cohesion , which is derived from the balance between average social support units and conflict levels within the team:

(10)

Team cohesion affects overall team resilience and performance, ensuring that the agents operate cohesively despite stressors [9,69].

Fig 2 illustrates the stress-performance modeling framework, showing how individual, environmental, and social factors collectively influence stress and performance outcomes. Table 3 summarizes the Eqs. and their descriptions, providing an overview of the modeling approach used in the simulation.

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Fig 2. Stress-performance modeling framework.

https://doi.org/10.1371/journal.pone.0332496.g002

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Table 3. Stress and performance modeling equations.

https://doi.org/10.1371/journal.pone.0332496.t003

3.1.1 Homogeneous teams.

Homo–Skill + Personality case is composed of members with similar personality traits and functional skills, the team exhibited the lowest overall outcomes among all tested configurations. As shown in Fig 3, final stress levels reached 0.96, the highest observed in this scenario, while health dropped to 0.39 and performance remained low at 0.39. The uniformity in both psychological and functional profiles may have limited the team’s ability to respond flexibly to prolonged stress exposure. With fewer differences in coping strategies or task approaches, the team might have struggled to adapt as challenges accumulated over time.

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Fig 3. Final Avg. for Homo-Team (500 Days).

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3.1.2 Time-based metrics – Homogeneous team.

Fig 4 presents the average trajectories of stress, performance, and health over the 500-day mission for homogeneous teams (Homo–Skill + Personality) across three personality trait profiles. In the Balanced Personality condition, stress escalated rapidly and leveled off near (0.85). Performance declined sharply over time, stabilizing around (0.2), while health dropped below (0.1) by the final phase. This uniform configuration may also have lacked the psychological diversity needed to buffer cumulative stress, contributing to accelerated declines in both functioning and well-being.

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Fig 4. Avg. Metrics for Homo-Team (500 days).

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In contrast, the High Conscientiousness and Low Neuroticism condition showed a slower and lower rise in stress, remaining near (0.65) toward the end. Performance declined gradually and stayed above (0.4) for most of the mission. Health remained high during the first three-quarters of the timeline and only dropped significantly after day 400, ending just above (0.2), suggesting this trait profile may support greater long-term stability and adaptive functioning under sustained isolation.

The High Extraversion and High Agreeableness team showed an early rise in stress, plateauing near (0.75). Performance declined at a rate similar to the Balanced group but with slightly higher values toward the end, settling near (0.25). Health deteriorated steadily after day 100 and approached the lower range by mission completion.

Taken together, these patterns suggest that homogeneous teams composed of individuals with Balanced Personality traits may be most vulnerable to performance and health degradation, while teams with High Conscientiousness and Low Neuroticism may better withstand the psychological demands of long-duration missions.

3.1.3 Heterogeneous teams.

In heterogeneous teams, outcomes varied depending on the combination of personality traits and skill diversity applied under each scenario.

Fig 5 presents the final average values for stress, performance, and health across the three heterogeneous configurations. In the High Conscientiousness and Low Neuroticism scenario, the hetero-skill + personality team achieved the most favorable results, with the lowest stress (0.58), highest performance (0.58), and highest health (0.78). The hetero-personality team showed moderate stress (0.71), performance (0.52), and health (0.74). The hetero-skill team had the highest stress (0.79), and lower performance (0.44) and health (0.47).

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Fig 5. Final Avg. for Hetero Team (3 Cases, 500 days).

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Under the Balanced Personality scenario, all heterogeneous teams showed elevated stress and reduced performance and health. The hetero-skill + personality team had stress at 0.82, with performance and health at 0.43 and 0.47, respectively. The hetero-skill team had similar stress (0.79), identical performance (0.44), and health (0.47). The hetero-personality team had the highest stress (0.85), with slightly lower performance (0.42) and health (0.45).

In the High Extraversion and High Agreeableness scenario, the hetero-personality team showed the best overall outcomes, with the lowest stress (0.65), highest performance (0.49), and health (0.47). The hetero-skill + personality team had slightly higher stress (0.80), with performance at (0.44) and health at (0.46). The hetero-skill team exhibited the highest stress (0.83), with performance and health at (0.43) and (0.44), respectively.

These findings suggest that the hetero-skill + personality configuration may offer more favorable outcomes in high-conscientiousness settings and could remain comparatively resilient across different personality conditions. In contrast, hetero-skill teams alone appeared to experience consistently elevated stress and reduced performance, potentially reflecting limited psychological adaptability.

3.1.4 Time-based metrics – Heterogeneous team.

Fig 6 illustrates the evolution of average stress, performance, and health over the 500-day mission across three personality trait scenarios. Each row corresponds to one heterogeneous team configuration hetero-skill + personality, hetero-personality, and hetero-skill while each column represents one of the core metrics.

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Fig 6. Avg. Metrics for Hetero-Team (3 Cases, 500 days).

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In the High Conscientiousness and Low Neuroticism scenario, the hetero-skill + personality configuration appeared to perform more favorably across the three metrics. It showed the lowest average stress (0.36), relatively high performance (0.69), and the most stable health levels (0.92). The hetero-personality team followed closely with stress around (0.43), performance near (0.63), and health approaching (0.88). In contrast, the hetero-skill team exhibited higher stress (0.56), with moderately lower performance (0.54) and health (0.62).

For the Balanced Personality scenario, all configurations experienced more pronounced declines in health and performance, while stress increased over time. The hetero-skill + personality team showed average stress near (0.53), performance around (0.56), and health at approximately (0.64). The hetero-personality team followed with stress around (0.59), performance near (0.52), and health at (0.57). The hetero-skill configuration exhibited slightly higher stress (0.58), with performance and health declining to around (0.52) and (0.61), respectively. These patterns could reflect reduced psychological buffering effects when personality traits are more moderate.

In the High Extraversion and High Agreeableness condition, the hetero-personality team appeared to achieve the most favorable average outcomes: stress remained lower (0.51), while performance and health were higher (0.58) and (0.67), respectively. The hetero-skill + personality team also maintained relatively stable metrics, with stress near (0.48), performance at (0.61), and health around (0.72). The hetero-skill configuration recorded higher stress (0.59) and comparatively lower performance (0.51) and health (0.56). These results imply that under socially expressive trait profiles, personality diversity may play a more critical role in sustaining team performance and well-being than functional diversity alone.

3.2.1 Homogeneous teams.

Fig 7 presents the individual stress, performance, and health metrics for astronauts in the homogeneous team configured with similar skill and personality profiles (Homo–Skill + Personality). Stress levels increased consistently across all six astronauts, beginning near (0.35–0.45) and rising above (0.85) for most by the end of the mission. Several individuals approached near-maximal stress during the final quarter, reflecting a shared vulnerability to prolonged exposure.

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Fig 7. Homo team – balanced personality.

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Performance followed a gradual downward trend, starting around (0.70) and declining below (0.50) after day (250). By the mission’s end, all agents converged within a narrow range between (0.42) and (0.47), indicating a uniform loss in task efficiency over time.

Health deteriorated more rapidly and earlier than the other metrics. Most astronauts experienced a steep decline between days (50) and (150), with values falling below (0.40) and stabilizing between (0.25) and (0.35) for the remainder of the mission. Few signs of recovery were evident after the initial drop.

These patterns point to a narrow range of behavioral responses in the team. With shared psychological and functional profiles, the group exhibited little divergence in stress adaptation or functional resilience. The absence of heterogeneity in both skill and personality may have constrained the team’s ability to distribute load or recover under stress, contributing to mission-long degradation across all agents.

3.2.2 Heterogeneous teams.

Fig 8 displays individual stress, performance, and health metrics over the 500-day mission for heterogeneous teams configured with (1) hetero-personality, (2) hetero-skill, and (3) hetero-skill + personality.

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Fig 8. Hetero team – Balanced personality (3 Cases).

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In the hetero-personality condition (bottom row), stress gradually increased for all astronauts, ending between (0.70) and (0.88). Performance declined steadily across the mission, with most agents converging around (0.42–0.46) by the final phase. Health showed wider variability some astronauts experienced early declines below (0.45) after day (200), while others maintained moderate health levels near (0.50) into the final third of the mission. This spread may reflect the benefits of trait-based heterogeneity in enabling diverse coping responses.

In the hetero-skill configuration (middle row), stress increased at a slightly faster rate than in the personality-based case, with most agents nearing or exceeding (0.85). Performance dropped more sharply during the second half of the mission, with end values commonly between (0.46) and (0.50). Health deteriorated earlier by day (300), nearly all astronauts had dropped below (0.50).

The hetero-skill + personality configuration (top row) showed the most favorable balance. Stress levels rose moderately and remained more evenly distributed across individuals, typically ranging from (0.60) to (0.80) by mission end. Performance declined more gradually and ended closer to (0.48–0.52) for most astronauts. Health also followed a more stable trajectory, with several agents maintaining values near or above (0.55) for much of the mission, even as others declined after day (250).

These individual patterns reinforce the value of integrating both psychological and functional diversity. Teams structured with hetero-skill + personality appeared better able to maintain performance and withstand long-term stressors, likely due to a wider range of adaptive strategies and complementary contributions among crew members.

3.2.3 Comparison.

Under the Balanced Personality condition, heterogeneous teams outperformed the homogeneous team across both average outcomes and individual level trajectories. Teams configured with hetero-personality and hetero-skill + personality exhibited comparatively lower stress, better performance retention, and more stable health throughout the mission.

The homogeneous team ended up with the highest final stress value (0.96), and the lowest performance (0.39) and health (0.39) scores. This pattern of decline was also evident in individual trajectories, where all six agents exhibited nearly identical degradation curves, particularly sharp early declines in health and converging stress levels above (0.85) by the final phase. Minimal intra-team variability suggested a lack of buffering capacity and resilience under cumulative stress.

Among the heterogeneous teams, the hetero-personality group ended with slightly lower stress (0.85), marginally better performance (0.42), and health (0.45) values. The hetero-skill team showed similar outcomes, with stress at (0.79), performance at (0.44), and health at (0.47). The hetero-skill + personality team concluded with stress at (0.82), performance at (0.43), and health at (0.47). While the final values across heterogeneous teams were close, their individual-level patterns revealed smoother declines and greater within team variability, indicating the presence of diverse coping responses and recovery behaviors.

Individual trajectories in heterogeneous teams displayed more varied stress and health adaptations, with some astronauts preserving functional capacity longer than others. In contrast, the homogeneous team showed limited divergence across all agents, reinforcing the interpretation that shared psychological and functional traits may constrain adaptive flexibility in prolonged, high-demand environments.

Taken together, these results suggest that incorporating both psychological and functional heterogeneity, especially in combination, may offer a more robust defense against cumulative stress and performance degradation in long-duration missions. However, the magnitude of this benefit appears contingent on the specific personality trait configurations. In particular, teams characterized by higher conscientiousness and lower neuroticism tended to experience slower stress accumulation and more resilient functional trajectories over time.

Although the simulation does not aim to forecast operational outcomes directly, it provides a structured platform to examine how specific team compositions influence group dynamics over time. These findings may contribute to the design of more adaptive crew selection strategies and inform mission planning for extended spaceflight scenarios.