The Martian environment, characterized by extreme aridity, frigid temperatures, and a lack of atmospheric oxygen, presents a formidable challenge for potential terraforming endeavors. This review article synthesizes current research on utilizing algae as biocatalysts in the proposed terraforming of Mars, assessing their capacity to facilitate Martian atmospheric conditions through photosynthetic bioengineering. We analyze the physiological and genetic traits of extremophile algae that equip them for survival in extreme habitats on Earth, which serve as analogs for Martian surface conditions. The potential for these organisms to mediate atmospheric change on Mars is evaluated, specifically their role in biogenic oxygen production and carbon dioxide sequestration. We discuss strategies for enhancing algal strains' resilience and metabolic efficiency, including genetic modification and the development of bioreactors for controlled growth in extraterrestrial environments. The integration of algal systems with existing mechanical and chemical terraforming proposals is also examined, proposing a synergistic approach for establishing a nascent Martian biosphere. Ethical and ecological considerations concerning introducing terrestrial life to extra-planetary bodies are critically appraised. This appraisal includes an examination of potential ecological feedback loops and inherent risks associated with biological terraforming. Biological terraforming is the theoretical process of deliberately altering a planet's atmosphere, temperature, and ecosystem to render it suitable for Earth-like life. The feasibility of a phased introduction of life, starting with microbial taxa and progressing to multicellular organisms, fosters a supportive atmosphere on Mars. By extending the frontier of biotechnological innovation into space, this work contributes to the foundational understanding necessary for one of humanity's most audacious goals-the terraforming of another planet.
Terraforming Mars toward sustainable life-supporting ecosystems poses unprecedented challenges. Extremophilic microbes, which thrive in Earth's most extreme environments, offer promising biological strategies for initial Mars colonization providing tools for resource mobilization and atmospheric engineering. This review synthesizes experimental evidence on microbial survival Mars-simulated conditions, highlights the ecological roles of extremophilic microbial consortia in biogeochemical cycling. We further discuss cutting-edge synthetic biology approaches to enhance microbial resilience. Yet, we emphasize the need to shift focus from single-species assessments to complex, synergistically interacting microbial communities, which may hold the key to establishing self-sustaining extraterrestrial biospheres. Finally, we consider planetary protection, ethical concerns, and future research priorities to responsibly perform Mars terraforming.
The poor fertility of Martian regolith, due to its lack of organic matter (OM) and nitrogen (N), limits its suitability as a plant substrate. While compost amendment enhances short-term fertility, the mechanisms underlying long-term OM stabilization, particularly through interactions with iron (Fe) minerals, remain poorly understood. This study explores OM fractionation and Fe mineral transformations in Mojave Mars Simulant (MMS-1), both pure (R100) and amended with compost (R70C30), across two consecutive cropping cycles (potato followed by Vicia faba). Following Vicia faba cultivation, total C increased 12-fold in R70C30 (18.8 g kg-1) compared to R100 (1.6 g kg-1), with a 140 % increase in amended and 90 % in pure regolith relative to post-potato levels. Both particulate organic matter (POM) and mineral-associated organic matter (MAOM) also increased substantially: POM-C rose 7-fold, while MAOM-C increased by 947 %, suggesting the formation of organo-mineral complexes. MAOM also exhibited a 447 % rise in total N and the lowest C/N ratio (∼9), consistent with more microbially processed and stabilized OM. Fe speciation via Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) revealed compost-driven enrichment of ferrihydrite and hematite, with distinct mineral profiles across POM and MAOM fractions. EXAFS further identified lepidocrocite and magnetite, phases undetected by XANES, highlighting the complementary role of reactive and crystalline Fe minerals in stabilizing OM in mineral matrices. These findings underscore the potential of organic amendments and leguminous crops to promote biologically functional, nutrient-rich substrates from Martian regolith simulants, offering critical insights for in situ resource utilization in space agriculture.
Over the last two centuries, great advances have been made in microbiology as a discipline. Much of this progress has come about as a consequence of studying the growth and physiology of individual microbial species in well-defined laboratory media; so-called "axenic growth". However, in the real world, microbes rarely live in such "splendid isolation" (to paraphrase Foster) and more often-than-not, share the niche with a plethora of co-habitants. The resulting interactions between species (and even between kingdoms) are only very poorly understood, both on a theoretical and experimental level. Nevertheless, the last few years have seen significant progress, and in this review, we assess the importance of polymicrobial infections, and show how improved experimental traction is advancing our understanding of these. A particular focus is on developments that are allowing us to capture the key features of polymicrobial infection scenarios, especially as those associated with the human airways (both healthy and diseased).
The widespread growth of higher plants on Mars following ecopoiesis has often been invoked as a method of generating atmospheric oxygen. However, one issue that has been overlooked in this regard is the fact that terrestrial plants do not thrive under conditions of low oxygen tension. A review of the relevant botanical literature reveals that the high oxygen demands of root respiration could limit the introduction of most plants on Mars until after terraforming has raised the atmospheric pO2 to 20-100 mbar. A variety of physiological strategies are discussed which, if it is possible to implement them in a genetically engineered plant specifically designed for life on Mars, might allow this problem to be overcome.
One of the most difficult tasks in terraforming Mars is the release into the atmosphere of CO2 bound by the surface of Mars. Even if a sufficiently dense CO2 atmosphere can be created by appropriate technology, the maintenance of CO2 concentration remains a problem. As Mars lacks plate tectonics as well as active volcanism, an Earth-like carbon cycle cannot be reproduced there. We suggest that Matteia sp., a lime-boring cyanobacterium isolated from Negev desert rocks, be used to dissolve carbonate rocks both for initial release of CO2 and in design of a Martian carbon cycle.
Understanding how hypobaria can affect net photosynthetic (P (net)) and net evapotranspiration rates of plants is important for the Mars Exploration Program because low-pressured environments may be used to reduce the equivalent system mass of near-term plant biology experiments on landers or future bioregenerative advanced life support systems. Furthermore, introductions of plants to the surface of a partially terraformed Mars will be constrained by the limits of sustainable growth and reproduction of plants to hypobaric conditions. To explore the effects of hypobaria on plant physiology, a low-pressure growth chamber (LPGC) was constructed that maintained hypobaric environments capable of supporting short-term plant physiological studies. Experiments were conducted on Arabidopsis thaliana maintained in the LPGC with total atmospheric pressures set at 101 (Earth sea-level control), 75, 50, 25 or 10 kPa. Plants were grown in a separate incubator at 101 kPa for 6 weeks, transferred to the LPGC, and acclimated to low-pressure atmospheres for either 1 or 16 h. After 1 or 16 h of acclimation, CO(2) levels were allowed to drawdown from 0.1 kPa to CO(2) compensation points to assess P (net) rates under different hypobaric conditions. Results showed that P (net) increased as the pressures decreased from 101 to 10 kPa when CO(2) partial pressure (pp) values were below 0.04 kPa (i.e., when ppCO2 was considered limiting). In contrast, when ppCO(2) was in the nonlimiting range from 0.10 to 0.07 kPa, the P (net) rates were insensitive to decreasing pressures. Thus, if CO(2 )concentrations can be kept elevated in hypobaric plant growth modules or on the surface of a partially terraformed Mars, P (net) rates may be relatively unaffected by hypobaria. Results support the conclusions that (i) hypobaric plant growth modules might be operated around 10 kPa without undue inhibition of photosynthesis and (ii) terraforming efforts on Mars might require a surface pressure of at least 10 kPa (100 mb) for normal growth of deployed plant species.
Synthetic biology, the design and synthesis of synthetic biological systems from DNA to whole cells, has provided us with the ultimate tools for space exploration and colonisation. Herein, we explore some of the most significant advances and future prospects in the field of synthetic biology, in the context of astrobiology and terraforming.
Mars is bitterly cold and dry, but robotic spacecraft have returned abundant data that indicate Mars once had a much warmer and wetter climate in the past. These data, the basis of the search for past or present life on Mars, suggest the possibility of returning Mars to its previous climate by global engineering techniques. Greenhouse gases, such as perfluorocarbons, appear to be the best method for warming Mars and increasing its atmospheric density so that liquid water becomes stable. The process of making Mars habitable for terrestrial organisms is called terraforming or planetary ecosynthesis. The process of introducing terrestrial ecosystems to Mars can be compared with a descent down a high mountain. Each drop in elevation results in a warmer, wetter climate and more diverse biological community. Beginning with a polar desert, the sequence of ecosystems passes through tundra, boreal forest, and temperate ecosystems where moisture determines the presence of desert, grassland, or forest. This model suggests a sequence for the introduction of ecosystems to Mars and the communities to search for potential colonizing species for Mars.
The primitive characteristics of the cyanobacterium Chroococcidiopsis suggest that it represents a very ancient type of the group. Its morphology is simple but shows a wide range of variability, and it resembles certain Proterozoic microfossils. Chroococcidiopsis is probably the most desiccation-resistant cyanobacterium, the sole photosynthetic organism in extreme arid habitats. It is also present in a wide range of other extreme environments, from Antarctic rocks to thermal springs and hypersaline habitats, but it is unable to compete with more specialized organisms. Genetic evidence suggests that all forms belong to a single species. Its remarkable tolerance of environmental extremes makes Chroococcidiopsis a prime candidate for use as a pioneer photosynthetic microorganism for terraforming of Mars. The hypolithic microbial growth form (which lives under stones of a desert pavement) could be used as a model for development of technologies for large-scale Martian farming.
The environmental conditions on present‑day Mars are far outside the range tolerated by known complex terrestrial life. Conceptual climate studies have suggested that, in hypothetical terraforming scenarios, artificially enhancing the greenhouse effect could restore Mars to more habitable surface conditions. Early colonizing terrestrial life on a warming Mars would plausibly consist of lichens and high‑alpine or high‑arctic plants. Here, we consider a later, more demanding step and investigate the thermal conditions under which the first tree could, in principle, grow on the Martian surface. Based on empirical treeline studies, we adopt thermal thresholds for a representative high‑elevation conifer: a growing season of at least 110 sols during which daily minimum temperatures exceed -6 °C, daily means exceed 6 °C, and daily maxima remain below 40 °C. In addition to liquid water and suitable substrates, O₂ at ~1 hPa and non‑toxic CO₂ levels are likely required; however, these non‑thermal constraints are not explicitly modelled and make the temperature thresholds necessary but not sufficient for tree viability. We use a high‑resolution surface energy balance model of Mars, assuming a pure CO₂ atmosphere with prescribed grey infrared opacity and neglecting the coupled water cycle, full atmospheric dynamics, photochemistry, and surface radiation, to estimate spatio‑temporal thermal windows for potential tree growth as a function of CO₂ surface pressure and additional greenhouse forcing. For a 100 hPa CO₂ atmosphere, near‑surface temperatures satisfying the treeline thresholds first appear when the added grey infrared opacity is ~ 0.39 optical depths. In our simulations, these thermal criteria are initially met not in the tropics (±25°), but in the low‑lying Hellas Basin. As either the CO₂ surface pressure or the imposed grey opacity is increased beyond the values required to open the thermal window, large regions of the southern hemisphere subsequently become thermally overheated and thus unsuitable for tree growth. In this sense, the thermal windows identified in our simulations mark conditions under which temperature would no longer be the primary limiting factor for tree growth, assuming that other essential environmental constraints (such as water availability, radiation environment, substrate properties, and atmospheric composition) are satisfied. We emphasize that this study deals with temperature only, which is an important factor in tree growth on Mars. Other factors that affect tree growth, including water, CO₂ limits, O2 limit, UV and ionizing radiation, and soil nutrients and microbial population, are not considered explicitly here.
Intergenerational justice is the core principle supporting the legacy of benefit toward future generations, including the perpetuation of species and their genetic diversity, as a key component of biospheric sustainability. Thirty percent of Earth's terrestrial habitats are now undergoing protection, biodiversity hotspots are being targeted, and there is increasing community awareness and engagement in conservation. However, the impending sixth mass extinction threatens to drive many species to extinction in the wild, irrespective of these interventions. Earth's biosphere is now undergoing terraforming through ecosystem destruction and modification, urbanization, and agriculture. Therefore, transformative cultural, political, and economic incentives are needed to maximize the legacy of the Earth's biodiversity and biospheric sustainability toward future generations. Reproduction and advanced biotechnologies can perpetuate species and their genetic diversity while also contributing to human and animal health and agricultural production. Advanced reproduction biotechnologies, including genetic engineering and synthetic biology, provide a new horizon for biospheric management, through the de-extinction of ancient species, restoring recently lost species, and maintaining the genetic diversity of extant species through wildlife biobanking. More extensive and inclusive conservation breeding programs and wildlife biobanking resources/facilities are desperately needed to perpetuate more than 3,000 Critically Endangered terrestrial/freshwater species; a goal fully attainable for amphibians and smaller fishes through global inclusion of stakeholders including private caregivers, plausible for freshwater mussels and crayfish, in development for reptiles and birds, and applicable for many mammals. As this capacity develops, many otherwise neglected species that are losing their natural habitat can be perpetuated solely in biobanks, thus enabling the more efficient utilization of resources toward meaningful field conservation primarily through habitat protection. The full potential of reproduction and advanced biotechnologies includes the development of artificial wombs to address the human population crisis and to avoid surrogacy mismatching during species restoration or de-extinction. The use of advanced reproduction biotechnologies for direct human benefit, for species management, and for biospheric sustainability, are subject to evolving ethical and legal frameworks, particularly regarding genetic engineering, transhumanism, and the de-extinction of ancient species.
A big-budget flop about terraforming Mars had a ground-aerial robot team predating Perseverance and Ingenuity.
In natural ecosystems, large-scale structure and function arise from the spatial coordination of local habitat shaped by environmental pressures. Replicating such multiscale organization in synthetic systems-where emergent form and function are governed solely by material composition-remains a fundamental challenge in design and engineering. Here, we developed an experimental, analytical, and computational framework to create self-organizing material patterns-Terraforms-using a ternary mixture of clay, water, and binder subjected to uniform mechanical pressure. These networked patterns form instantaneously at material interfaces and exhibit 3D scale-free organization, positioned between random and regular configurations, mimicking diverse ecological patterns, with planar symmetry and microtopographic fractality. Systematic variation of relative material proportions (RMPs) revealed a critical regime-50% clay, 15-20% water, and 30-35% binder-with a water-to-binder (W/B) ratio close to the Pacioli golden ratio (1.62), yielding Pareto-optimal patterns. Within this regime, network structures minimize eco-stress, maximize hygroscopic capacity, and enhance systemic stability, thereby enabling their quantification. Transitions between pattern topologies follow gradients in the W/B ratio, consistent with a Fibonacci sequence, marking metastable states between disorder and order. Identical W/B ratios can produce distinct topologies, indicating multistability under fixed composition. In Terraforms, the W/B ratio governs short- and long-range bonding, analogous to ecological interactions, while clay acts as a foundational agent, comparable to habitat-forming species. Our results show that complex, functionally optimized network structures can emerge solely from material interactions dictated by RMPs, without systemic control, biological processes, or environmental heterogeneity. These findings establish design rules for programmable, nature-inspired materials with transformative potential for eco-functional infrastructure, ecosystem restoration, and the creation of integrated natural-built environments with deliberately engineered functions - a process we term ecological terraforming.
More than 500 million years ago, a streptophyte algal population established a foothold on land and started terraforming Earth through an unprecedented radiation. This event is called plant terrestrialization and yielded the Embryophyta. Recent advancements in the field of plant evolutionary developmental biology (evo-devo) have propelled our knowledge of the closest algal relatives of land plants, the zygnematophytes, highlighting that several aspects of plant cell biology are shared between embryophytes and their sister lineage. High-throughput exploration determined that routes of signaling cascades, biosynthetic pathways, and molecular physiology predate plant terrestrialization. But how do they assemble into biological programs, and what do these programs tell us about the principal functions of the streptophyte cell? Here, we make the case that streptophyte algae are unique organisms for understanding the systems biology of the streptophyte cell, informing on not only the origin of embryophytes but also their fundamental biology.
In the era of deep space exploration, extremophile research represents a key area of research w.r.t space survival. This review thus delves into the intriguing realm of 'Space and Astro Microbiology', providing insights into microbial survival, resilience, and behavioral adaptations in space-like environments. This discussion encompasses the modified behavior of extremophilic microorganisms, influencing virulence, stress resistance, and gene expression. It then shifts to recent studies on the International Space Station and simulated microgravity, revealing microbial responses that impact drug susceptibility, antibiotic resistance, and its commercial implications. The review then transitions into Astro microbiology, exploring the possibilities of interplanetary transit, lithopanspermia, and terraforming. Debates on life's origin and recent Martian meteorite discoveries are noted. We also discuss Proactive Inoculation Protocols for selecting adaptable microorganisms as terraforming pioneers. The discussion concludes with a note on microbes' role as bioengineers in bioregenerative life support systems, in recycling organic waste for sustainable space travel; and in promoting optimal plant growth to prepare Martian and lunar basalt. This piece emphasizes the transformative impact of microbes on the future of space exploration.
Earth's biodiversity is increasingly threatened and at risk. We propose a passive lunar biorepository for long-term storage of prioritized taxa of live cryopreserved samples to safeguard Earth's biodiversity and to support future space exploration and planet terraforming. Our initial focus will be on cryopreserving animal skin samples with fibroblast cells. An exemplar system has been developed using cryopreserved fish fins from the Starry Goby, Asterropteryx semipunctata. Samples will be expanded into fibroblast cells, recryopreserved, and then tested in an Earth-based laboratory for robust packaging and sensitivity to radiation. Two key factors for this biorepository are the needs to reduce damage from radiation and to maintain the samples near -196° Celsius. Certain lunar sites near the poles may meet these criteria. If possible, further testing would occur on the International Space Station prior to storage on the Moon. To secure a positive shared future, this is an open call to participate in this decades-long program.
Extremophiles, throughout evolutionary time, have evolved a plethora of unique strategies to overcome hardships associated with the environments they are found in. Modifying their genome, showing a bias towards certain amino acids, redesigning their proteins, and enhancing their membranes and other organelles with specialised chemical compounds are only some of those strategies. Scientists can utilise such attributes of theirs for a plethora of biotechnological and astrobiological applications. Moreover, the rigorous study of such microorganisms regarding their evolution and ecological niche can offer deep insight into science's most paramount inquiries such as how life originated on Earth and whether we are alone in the universe. The intensification of studies involving extremophiles in the future can prove to be highly beneficial for humanity, even potentially ameliorating modern problems such as those related to climate change while also expanding our knowledge about the complex biochemical reactions that ultimately resulted in life as we know it today.