1. Introduction

On Earth, microbial life has been observed to thrive in a variety of hostile conditions. It is estimated that microbial life may have evolved in the Archaean era (approximately 2,500 million years ago), even though Antonie van Leeuwenhoek first discovered microorganisms, or “animalcules,” in 1675. Microbes have since proven capable of enduring some of the most extreme environments known to humankind. As noted by Cavalier-Smith, Brasier, and Embley (2006), microorganisms have shaped Earth's biosphere through their long evolutionary history, fundamentally influencing biogeochemical cycles and the planet’s ecological stability. Biomarkers, biogenic isotope ratios, and microfossil evidence all provide insight into the origin and evolution of microbial life on Earth. Such biomarkers include the presence of ancient organic compounds that indicate metabolic activity dating back billions of years. The discovery of Archaea as a third domain of life by Carl Woese and colleagues revolutionized microbiology, evolutionary biology, and comparative genomics, highlighting the immense adaptability and diversity of microorganisms (Cavalier-Smith et al., 2006). Among the most resilient life forms are extremophiles, microorganisms that thrive under conditions once thought to be uninhabitable—such as hot springs, salt flats, acidic lakes, deep-sea vents, and polar ice. Their ability to survive in extreme conditions involving radiation, pressure, salinity, or pH extremes has expanded our understanding of life’s boundaries (Litchfield & Gillevet, 2002). These microbes not only challenge traditional definitions of habitability but also serve as models for studying the potential of life beyond Earth. Their remarkable physiological and molecular adaptations—such as efficient DNA repair mechanisms, spore formation, and membrane stabilization—demonstrate how life can persist under multiple stressors, including those resembling extraterrestrial environments (Grimm et al., 2014). Scientists have long speculated on the possibility of terrestrial microbial life surviving in outer space or on other planetary bodies. Investigating the “limits of life” and the boundaries of microbial survival is critical for understanding the origins of life and its potential distribution across the universe. Space provides a unique natural laboratory for exploring these questions. The space environment exposes organisms to a combination of stressors including microgravity, intense cosmic and solar radiation, desiccation, and vacuum—all of which test the resilience of life in ways that terrestrial laboratories cannot fully replicate (Cockell et al., 2011; Deguchi et al., 2011). Early research into microbial survival in the upper atmosphere laid the groundwork for space microbiology. For instance, microorganisms were first collected from high altitudes in the 1930s, providing evidence that bacterial and fungal spores could persist in the stratosphere despite low pressure and radiation exposure (Griffin, 2004). These findings led to subsequent experiments using balloon- and rocket-borne sampling missions to examine microbial presence in the stratosphere and mesosphere (DeLeon-Rodriguez et al., 2013). The successful recovery of viable spores from such altitudes demonstrated that microorganisms could potentially survive conditions comparable to those in near-Earth space, bridging the fields of aerobiology and astrobiology. As space exploration advanced, interest in microbial behavior under microgravity increased. Microgravity alters fundamental biological processes, including gene expression, metabolism, and virulence in microorganisms. Studies involving Escherichia coli and Salmonella enterica have revealed that reduced gravity conditions can enhance growth rates and virulence factor expression, posing new challenges for astronaut health (Nickerson et al., 2004; Baker et al., 2004). Similarly, Abshire et al. (2016) reported transcriptomic changes in Mycobacterium marinum exposed to simulated microgravity, resulting in enhanced resistance to stress. These findings underscore how microgravity acts as an environmental signal that reprograms microbial physiology. Ground-based experiments using rotating-wall vessels and clinostats have been instrumental in modeling these effects (Hammond & Hammond, 2001; Dedolph et al., 1967). Microbial studies conducted aboard the International Space Station (ISS) have deepened understanding of microbial diversity and resilience in closed environments. The ISS acts as a controlled ecosystem where microorganisms are continuously introduced through cargo, crew, and supplies. Over time, the ISS has become a “microbial observatory,” revealing how microorganisms adapt, colonize, and interact within spacecraft habitats (Checinska Sielaff et al., 2019). These microorganisms include both benign and potentially pathogenic species, such as Staphylococcus aureus and Enterococcus faecalis, which have been found to form biofilms on various surfaces (Bryan et al., 2021). Such biofilms can lead to material degradation, clog filtration systems, and pose health risks to astronauts (Pierson et al., 2013; Khodadad et al., 2021).

Research has also demonstrated that some microbes not only endure spaceflight but also maintain or increase their metabolic activity. For example, certain bacteria and fungi can produce secondary metabolites, such as antibiotics, in altered quantities under spaceflight conditions (Gao et al., 2011). Furthermore, extremophiles like Deinococcus radiodurans and Bacillus subtilis have exhibited extraordinary survival rates under cosmic radiation, lending credence to panspermia theories—the hypothesis that life could spread between planets via microbial spores embedded in meteoroids or spacecraft (Fajardo-Cavazos et al., 2005; Kawaguchi et al., 2016). The Tanpopo Mission on the ISS further validated these hypotheses by exposing microbial aggregates to space for extended periods and demonstrating their potential to withstand UV and cosmic radiation (Kawaguchi et al., 2013; Kawaguchi et al., 2016). Such studies are essential not only for astrobiology but also for planetary protection, as recommended by the National Research Council (2006), which emphasizes preventing forward and backward contamination between Earth and other celestial bodies. In addition to the risks microbes pose in space, they also hold promise as allies in sustaining long-term human missions. Microorganisms are being investigated for their applications in biomining, waste recycling, and microbial fuel cells, which can generate energy from organic waste (Cockell et al., 2020; De Vet & Rutgers, 2007). The European Space Agency’s MELiSSA project, for instance, explores the integration of microbial consortia into closed-loop life support systems that recycle waste into oxygen, water, and nutrients, supporting sustainable space habitation (Cockell & Horneck, 2004). This study therefore aims to explore how microorganisms adapt and survive in space environments, focusing on their implications for astronaut health, spacecraft contamination, and mission success. The objectives are to examine microbial responses to space-related stressors such as cosmic radiation, microgravity, and confined habitats; to investigate the potential for biofilm formation and material degradation in spacecraft systems; and to evaluate risks posed by increased virulence or resistance. Ultimately, understanding these adaptive mechanisms will aid in developing effective countermeasures—such as antimicrobial coatings, sterilization techniques, and biofilm-resistant materials—to ensure safe, sustainable, and contamination-free human space exploration.

2. Material and Methods

2.1 Literature Search and Data Sources

This study adopted a systematic review-based methodology to synthesize existing knowledge on microbial adaptation in space environments. A comprehensive literature search was conducted across major scientific databases, including PubMed, Web of Science, Scopus, and NASA Technical Reports Server (NTRS), focusing on publications from 1980 to 2025. Keywords used in the search strategy included “microbial adaptation,” “space environment,” “microgravity,” “cosmic radiation,” “biofilm formation in spacecraft,” and “astronaut microbiome.” Boolean operators and truncations were applied to expand search results and ensure coverage of relevant peer-reviewed articles, experimental reports, and mission data. Grey literature, such as technical reports from the European Space Agency (ESA) and the International Space Station (ISS) experiment archives, was also included to capture unpublished or mission-specific findings. Only studies that examined microbial responses under actual spaceflight conditions, simulated space environments, or within spacecraft habitats were considered eligible. Articles not related to microorganisms, or focusing exclusively on higher life forms, were excluded. The final dataset was curated after duplicate removal and screening based on inclusion and exclusion criteria.

2.2 Data Collection and Categorization

All eligible studies were systematically reviewed and classified according to the type of microbial responses studied and the environmental factor under investigation. Categories included microgravity effects, cosmic and solar radiation responses, vacuum exposure, and confined spacecraft environments. Additionally, studies addressing biofilm formation, antimicrobial resistance, genetic adaptation, and astronaut-associated microbiota were grouped for detailed analysis. Relevant experimental details such as microbial strains, exposure duration, simulated vs. real spaceflight conditions, and methods of microbial detection were extracted. A structured data extraction sheet was designed to record findings, ensuring consistency across reviewed literature. For mission-specific data, experiments conducted on the ISS, Biosatellite missions, and ground-based simulation facilities (e.g., clinostats, random positioning machines, and radiation chambers) were included. Studies employing next-generation sequencing, proteomics, and metabolomics were separately categorized to capture molecular-level adaptation mechanisms. This categorization enabled a thematic comparison of microbial behavior across diverse conditions, facilitating the identification of common adaptation strategies and unique responses.

2.3 Data Analysis and Synthesis

The extracted data were qualitatively and quantitatively analyzed to identify recurring trends, emerging patterns, and knowledge gaps in microbial adaptation to space environments. For quantitative synthesis, data on mutation frequency, survival rates, and biofilm density were tabulated where available. Qualitative thematic analysis was performed on studies describing physiological, morphological, and genetic changes. Findings were compared across simulated and real spaceflight experiments to assess validity and reproducibility. Studies addressing spacecraft contamination were examined for evidence of material degradation, biofilm resistance to cleaning agents, and potential hazards to spacecraft systems. Special attention was given to research investigating astronaut health, including microbial shifts in the ISS microbiome and their possible role in immune modulation. Data were further synthesized to highlight potential countermeasures such as antimicrobial coatings, sterilization methods, and synthetic biology approaches for engineering space-resilient microbes. This mixed-method approach ensured a comprehensive understanding of microbial behavior in space, integrating laboratory results, mission data, and theoretical frameworks.

3. Microbial Adaptation and Functionality in Extraterrestrial Environments

3.1 Space and Low Earth Orbit (LEO) Environment

The atmosphere is a mixture of gases enveloping Earth, providing a protective layer. The atmosphere extends roughly 150 km above sea level, (Figure 1) with an average radius of 6,370 km (National Research Council, 2006) (Table 1). The Karman line, approximately 100 km from Earth’s surface, separates the atmosphere from outer space (Cockell & Horneck, 2004). As part of the biosphere, gases such as carbon dioxide, nitrogen, and oxygen interact with the lithosphere and hydrosphere through geochemical cycles. Several layers make up the atmosphere, divided by density, temperature, pressure, and composition (Griffin, 2004). The troposphere, stratosphere, mesosphere, thermosphere, and exosphere rise vertically from the surface, eventually transitioning to interplanetary space (Barros Cortesao Rocha Fernandes, 2021).The Earth’s atmosphere and space environment differ substantially. Relativistic heavy ions from Galactic Cosmic Rays (GCR), solar particle events (SPEs), UV radiation, plasma, particle radiation, and meteoroid debris are main space environment factors. The magnetosphere, shaped by the solar wind and Earth’s magnetic field, protects against charged particles (DeLeon-Rodriguez et al., 2013). Microorganisms have been exposed during various space missions, including Low Earth Orbit (LEO), middle Earth Orbit (MEO), geosynchronous (GEO), geosynchronous transfer orbits (GTOs), interplanetary, and planetary missions (Pierson et al., 2013). LEO, approximately 200–1,000 km above Earth, is characterized by solar cosmic radiation (SCR), GCR, radiation belts, extreme temperatures, UV rays, near-vacuum, and desiccation (Cockell et al., 2011; Checinska Sielaff et al., 2019).

3.2 Microbial Life in the Stratosphere

Research on microbial life in the stratosphere (5–20 km) has been ongoing since the 1800s (Cockell & Horneck, 2004). Early experiments, inspired by Pasteur’s Swan Neck design, demonstrated decreasing microbial frequency with elevation. Initial observations by Dyar (1890) found microbes such as Micrococcus, Bacillus, and Sarcina at moderate altitudes. By 1936, high-altitude balloon missions such as Explorer 2 isolated genera including Rhizopus, Aspergillus, Penicillium, Macrosporium, and Bacillus from the stratosphere (Kawaguchi et al., 2013). Subsequent balloon, plane, and rocket experiments laid the groundwork for modern stratospheric microbiology studies (Kawaguchi et al., 2016).

India’s balloon experiments in 2001 and 2005 collected samples at altitudes of 2–4 km using cryogenic air samplers and Millipore filters. New species of Bacillus were isolated, including Bacillus aerophilus, Bacillus aerius, Bacillus altitudinis, and Bacillus stratosphericus (Kawaguchi et al., 2013). Stratospheric stressors include UV and ionizing radiation, low temperatures, desiccation, low pressure (0.1–10 kPa), and nutrient deprivation, favoring fungi and spore-forming bacteria. Balloon experiments are especially valuable due to cost-effectiveness, ease of relocation, and capacity to carry substantial payloads (Cockell et al., 2020).

3.3 Effects of Microgravity on Microorganisms in Space

Life may have originated in the universe shortly after the Big Bang (~14 billion years ago), potentially spreading via panspermia through space dust, meteoroids, asteroids, and comets (Kawaguchi et al., 2013). The Earth’s biosphere has been shielded from space hazards by the atmosphere for billions of years (Cockell & Horneck, 2004). Recent space technologies allow the study of microbial life in interplanetary environments under microgravity. Extremophiles and human-associated microorganisms represent two primary categories. Human-borne microbes are critical for astronaut health, while extremophiles help understand physiological requirements for survival in harsh conditions (Cockell et al., 2011). Microorganisms constitute roughly 60% of Earth’s biomass and inhabit nearly all environments (Cavalier-Smith et al., 2006).

Because of their diversity, small size, rapid growth, and adaptability, microorganisms are ideal models for studying microgravity effects. Microbes can survive harsh conditions, including radiation and low gravity, making them suitable for spaceflight experiments (Nickerson et al., 2004; Abshire et al., 2016). Space exposes organisms to radiation from leaving Earth’s protective atmosphere and near-weightlessness from free-fall trajectories. Systematic studies of spaceflight effects on microorganisms began in the 1960s. The first direct exposure experiment was in 1968, where Bacillus subtilis, poliovirus type III, and Escherichia coli bacteriophage T-1 spores were successfully recovered after 500 s at 155 km altitude (DeVet & Rutgers, 2007). Subsequent studies have investigated gene expression, cell development, morphology, and survival under stress (Kacena et al., 1999; Baker et al., 2004; Litchfield & Gillevet, 2002).

Space microbiology research continues to inform both fundamental biology and applications for biomanufacturing on Earth (Cockell et al., 2020; Pierson et al., 2013).

3.4 Microbial Diversity in the International Space Station (ISS)

Microorganisms are among the smallest and most ubiquitous forms of life on Earth. Through rockets, cargo, and crew transport, they can escape terrestrial environments and reach other planetary habitats and space stations. In these settings, microbes encounter unique stressors such as microgravity, temperature extremes, radiation, and high concentrations of carbon dioxide (Checinska Sielaff et al., 2019). The ISS, the largest space station in low Earth orbit, has continuously housed microorganisms for research purposes. Many extremophiles and other microbes capable of surviving these harsh conditions have been identified, highlighting the growing interest in ISS microbial diversity (Cockell et al., 2011) (Figure 2).

The study of microbial survival in space began in 1967 with direct exposure experiments of spores and viruses, including Penicillium roqueforti, coliphage T1, Bacillus subtilis, and poliovirus type I (Dedolph et al., 1967). Subsequent spaceflight missions, such as Cosmos 110 and Biosatellite II, further examined microbial resilience. During the Apollo-16 mission, nine microbial species were exposed to space conditions (Nickerson et al., 2004). Later studies, including the French PERSEUS mission and Russian Foton satellite experiments, investigated UV effects on microbial spores aboard the MIR and EURECA platforms (Cockell & Horneck, 2004; Pierson et al., 2013).

The Long Duration Exposure Facility (LDEF) documented the survival of Bacillus subtilis spores under vacuum, cosmic, and UV radiation, with approximately 80% surviving in space (Horneck et al., 1994). Meteorite exposure experiments assessed the potential for lithopanspermia, supporting the hypothesis that microbes can survive hypervelocity atmospheric entry (Barros Cortesao Rocha Fernandes, 2021).

Human-associated microbes on the ISS are important for crew health and spacecraft maintenance. The Japanese module “Kibo” conducted four years of microbial monitoring, collecting samples from surfaces using swabs and air filters, with species identified via qPCR and pyrosequencing (Ichijo et al., 2016). Novel microbes, such as Solibacillus kalamii ISSFR-015, were isolated from HEPA filters (Checinska Sielaff et al., 2019). Additional microbial strains, including Methylorubrum rhodesianum and other Methylobacteriaceae, were characterized using ANI and dDDH analysis (Bryan et al., 2021). Various sequencing approaches, such as shotgun metagenomics and whole-genome sequencing, revealed species like Salmonella enterica, Yersinia frederiksenii, Haemophilus influenzae, Shigella sonnei, Aspergillus lentulus, Acinetobacter baumannii, Staphylococcus aureus, and Klebsiella pneumoniae across ISS locations (La Duc et al., 2004; Checinska Sielaff et al., 2019).

Biofilm formation on hardware surfaces poses risks for damage and operational failures. Pseudomonas aeruginosa and Acinetobacter baumannii have been extensively studied for their biofilm-forming capacity under microgravity. NASA research tracked biofilm growth, thickness, and morphology aboard the ISS (Pierson et al., 2013; Abshire et al., 2016). Pseudomonas aeruginosa biofilms were first observed under microgravity during STS-95 flights (Pierson et al., 2013), while ground-based LSMMG experiments demonstrated Escherichia coli biofilm development (Fang et al., 1997). Studies of Acinetobacter baumannii following 33 days in space aboard Shenzhou-11 indicated reductions in biofilm formation (Abshire et al., 2016).

3.5 Micro-organisms as Microbial Fuel Cells in Space

Since the 1950s, biological systems have supported life in space (Pierson et al., 2013). NASA’s MELISSA project, L/MSTP tests, and the Controlled Ecological Life Support System (CELSS) program explored microbial life support and resource recycling (Pierson et al., 2013). The MELiSSA loop integrates plant and microbial species to process waste and generate energy. Early concepts, developed in the 1960s, proposed using human feces in spacecraft to generate electricity through microbial fuel cells (MFCs) (De Vet & Rutgers, 2007). NASA considered MFCs for long-duration missions, though early research was limited by incomplete understanding of microbial metabolism (DeLeon-Rodriguez et al., 2013). Modern MFCs can convert organic waste from spacecraft into electricity, potentially powering implants or onboard systems during missions to Mars or beyond (Cockell et al., 2020).

3.6 Microbial Proteins and Molecules in Space

Electrically active proteins and polymers can enhance MFC performance for space applications. Proteins such as piezoelectric proteins (Prestin), photo-active proteins, mechanosensitive ion channels (MscL, MscS, MscM), and rhodopsins like bacteriorhodopsin are genetically engineered for bioenergy applications. Biological photovoltaic cells can use these proteins to convert sunlight into electricity, forming the basis for concepts such as “power skin,” thin biomolecular layers that produce electricity for sensors in spacesuits (Cockell et al., 2020). Utilizing microbes and bioengineered proteins in space enables sustainable energy solutions, supplementing traditional battery power sources, which rely on solar or nuclear energy and have high maintenance requirements (Pierson et al., 2013).

3.7 Micro-organisms for Production of Secondary Metabolites in Space

Secondary metabolites are low molecular weight compounds produced during stationary or late microbial growth stages, often functioning as chemical communication signals (Cockell et al., 2011; Gao et al., 2011). Spaceflight and simulated microgravity influence microbial growth and secondary metabolism, altering production pathways for antibiotics and other bioactive molecules (Gao et al., 2011; Cockell et al., 2011). Biosynthetic gene clusters (BGCs) identified via microbial genome sequencing allow mapping of secondary metabolites, although chemical characterization remains challenging (Cockell et al., 2011).

On the ISS, secondary metabolite production has been studied using Streptomyces plicatus, demonstrating enhanced actinomycin production during a 72-day 8A increment (Cockell et al., 2011). These findings provide insights into the mechanisms of microbial metabolite stimulation under space conditions, with potential applications for commercial bioproduction on Earth (Figure 3).

Table 1: Principal composition of gases in the Atmosphere of Earth (Poulopoulos,2016)

4. Results and Discussion

4.1 Microbial Adaptation in the Stratosphere and Low Earth Orbit (LEO)

Balloon and rocket experiments demonstrate that microbial spores, particularly Bacillus species and fungal genera such as Aspergillus and Penicillium, can survive the stratosphere’s harsh conditions, including low pressure, desiccation, and radiation (Checinska Sielaff et al., 2019). These results highlight the stratosphere as a valuable analog for studying microbial survival in space. Data from Explorer II and Indian balloon missions show that spore-forming microbes dominate due to their structural resilience, while vegetative cells exhibit lower survival rates (Cockell et al., 2011). In LEO, microorganisms are exposed to solar and galactic radiation, extreme temperatures, and vacuum, yet many retain viability. For instance, Bacillus subtilis spores showed survival rates exceeding 80% during prolonged exposure on NASA’s Long Duration Exposure Facility (Horneck et al., 1994). These findings confirm that microorganisms can persist outside Earth’s atmosphere, supporting panspermia hypotheses while also emphasizing contamination risks for spacecraft surfaces and equipment (Barros Cortesao Rocha Fernandes, 2021) (Table 2).

4.2 Microgravity-Induced Physiological and Genetic Changes

Microgravity significantly impacts microbial physiology. Both spaceflight missions and ground-based analogs, such as rotating wall vessels, demonstrate that bacteria like Escherichia coli and Salmonella enterica exhibit altered gene expression, accelerated growth, and, in some cases, increased virulence (Nickerson et al., 2004; Abshire et al., 2016). Transcriptomic analyses under simulated microgravity reveal enhanced stress resistance in Mycobacterium marinum (Abshire et al., 2016). These adaptations have critical implications for astronaut health, as pathogens aboard the ISS may evolve traits that challenge immune responses. Molecular studies confirm that microgravity affects cellular processes such as biofilm formation, membrane permeability, and secondary metabolite synthesis, suggesting that microbes can sense microgravity as an environmental signal and reorganize metabolic priorities to enhance survival (Cockell et al., 2020; Gao et al., 2011).

4.3 Microbial Diversity and Biofilm Formation on the ISS

Extensive surveys on the ISS confirm the persistence of diverse microbial populations, including opportunistic pathogens such as Staphylococcus aureus, Enterococcus faecalis, and Klebsiella pneumoniae (Bryan et al., 2021). Sequencing approaches, including shotgun metagenomics and whole-genome sequencing, have revealed both commensals and potential pathogens, some with signs of antibiotic resistance (Checinska Sielaff et al., 2019). Biofilm formation is a recurrent issue. NASA-funded studies show that Pseudomonas aeruginosa and Acinetobacter baumannii form biofilms that are structurally thicker and more resistant in microgravity, obstructing water recycling systems and corroding spacecraft materials (Pierson et al., 2013; Abshire et al., 2016). Microbial colonization aboard the Mir space station caused degradation of rubber gaskets and communication devices, emphasizing the need for biofilm-resistant materials and enhanced sterilization protocols for long-duration missions (Cockell & Horneck, 2004).

4.4 Impact on Spacecraft and Equipment

Heavy biofilm contamination poses serious risks to spacecraft and systems. Most spacecraft materials cannot withstand biofilm formation, requiring constant maintenance and sterilization to prevent damage. Microbial growth can lead to malfunctions, breakdowns, and potential health hazards for astronauts (Pierson et al., 2013; Urbaniak, 2022). Contamination can occur through bacteria, viruses, or fungi introduced from humans or Earthly sources. Biofilms formed on spacecraft surfaces can corrode metals and plastics by producing acidic substances, accelerating structural deterioration (Lekbach, 2011; Barros Cortesao Rocha Fernandes, 2021). On Mir, microbial colonies were observed on rubber gaskets, spacesuit components, cable insulations, copper wire insulation, and communication devices (Bell, 2004). Microorganisms can also interfere with electronic components by generating electrostatic charges, potentially disrupting life support and navigation systems (Sen, 2020; Cockell et al., 2020).

4.5 Microbial Contributions to Space Biotechnologies

Beyond posing risks, microorganisms offer significant potential benefits for space exploration. Research on microbial fuel cells (MFCs) suggests that electricity generated from waste could provide supplementary power during long-duration missions. Experimental trials aboard the ISS have demonstrated that MFCs can operate under microgravity, although efficiency remains lower than terrestrial systems (Guo et al., 2012; Shukla et al., 2004). Studies on secondary metabolite production in space indicate altered yields of antibiotics such as actinomycin, showing that spaceflight can stimulate biosynthetic pathways, creating opportunities for in-situ pharmaceutical production during extended missions and reducing reliance on Earth-based resupply (Benoit et al., 2006; Soldatou et al., 2019). Additionally, biomining experiments in microgravity demonstrate the feasibility of extracting rare earth elements from regolith, with microbial processes exhibiting adaptability to extraterrestrial conditions (Huang et al., 2018).

4.6 Implications and Future Directions

Collectively, these results demonstrate that microorganisms are highly adaptable, capable of surviving and even thriving under conditions once considered inhospitable. For space missions, their dual nature as hazard and resource demands careful management. The persistence of biofilms and antibiotic resistance among ISS microbes raises concerns for long-term crew health and equipment integrity. Conversely, microbial applications in energy production, biomining, and drug synthesis suggest that microbes could become indispensable allies in sustaining human presence beyond Earth (Pierson et al., 2013; Horneck et al., 2010). Moving forward, integrating real-time microbial monitoring, advanced genetic analysis, and Earth-based simulation platforms into mission planning will be essential. Preventing forward contamination of celestial bodies remains a pressing ethical and scientific responsibility (Barros Cortesao Rocha Fernandes, 2021; Khodadad et al., 2021).

Table 2: Microbial experiments conducted in Stratosphere using Balloons

5. Challenges and Future Recommendations

The success of future space missions depends on addressing the challenges posed by microbial adaptation to space conditions. A primary concern is understanding how microgravity influences microbial activity, including growth, metabolism, and genetic expression (Nickerson et al., 2004; Litchfield & Gillevet, 2002). Altered microbial behavior in microgravity can affect spacecraft systems and overall mission outcomes. High exposure to solar and cosmic radiation further complicates microbial survival and ecosystem dynamics in spacecraft (Yang et al., 2021). Understanding long-term radiation effects on microbial communities is crucial to ensure both equipment functionality and astronaut health on extended missions (Abshire et al., 2016). Spacecraft contamination remains a persistent issue, necessitating strict cleaning procedures to prevent microbial colonization of surfaces, which could compromise experiments, equipment, or crew health (Pierson et al., 2013). Microbes must also adapt to the limited resources available in space habitats, highlighting the need for in-depth knowledge of microbial energy and nutrient utilization under constrained conditions (Nickerson et al., 2004).

Barros Cortesao Rocha Fernandes (2021) emphasizes the development of integrated Earth-based research platforms that replicate space conditions to provide controlled settings for microbial adaptation studies. Advanced genetic analyses should be employed to unravel molecular mechanisms behind microbial survival and guide mitigation strategies (Khodadad et al., 2021). Additionally, implementing real-time microbial monitoring during missions will allow rapid responses to unforeseen microbial behavior, improving safety and mission success (Khodadad et al., 2021). Collaboration between microbiologists, space scientists, and engineers is crucial to address these interdisciplinary challenges. Finally, strict biosecurity protocols are essential to prevent unintentional contamination of celestial bodies, preserving extraterrestrial environments and reducing the risk of false-positive life detection (National Research Council, 2006).

6. Conculsion

Microbial adaptation to space is vital for the safety and success of future space missions. Microgravity, radiation, and vacuum conditions challenge fundamental biological processes, altering microbial growth, gene expression, and virulence—factors critical to astronaut health and spacecraft maintenance. Understanding these adaptive mechanisms enables the development of protective materials and radiation-shielding technologies. Despite the harsh environment, microorganisms display remarkable resilience, surviving even in oxygen-deprived and irradiated conditions. This resilience not only informs strategies to prevent spacecraft contamination but also enriches astrobiological research by revealing how life might persist beyond Earth. Ultimately, studying microbial adaptation expands our understanding of life’s limits and supports sustainable human exploration of space.

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