Search Results (262)

Viruses are abundant and widespread in extreme marine environments, such as sea ice, hydrothermal vents, and ocean trenches. They occur at temperatures up to 122 °C and down to −30 °C and pressures exceeding 100 MPa. Their distribution in these environments is closely correlated with that of their extremophile hosts, which are mostly bacteria, archaea, and microeukaryotes. Viruses have been shown to be capable of long-term survival in conditions simulating interstellar conditions. However, for them to reproduce, they would still need a host. Many recent astro-biological investigations have focused on habitability, specifically the ability of a planet to support the activity of at least one lifeform. The most likely candidates for extraterrestrial habitability in our solar system are the sea ice moons of Jupiter and Saturn, namely Europa and Enceladus. These are both thought to contain subsurface oceans of liquid water and potentially access to the necessary elements for microbial growth. If microorganisms were to be detected in these extraterrestrial environments, viruses might also be found coexisting with their host cells. Full article

Methanogens, or methanogenic archaea (MA), are among the most ancient and widely distributed microorganisms, characterized by a unique metabolism that generates methane (CH₄) as the terminal product of anaerobic respiration. Their ability to grow and/or survive across a wide range of environmental conditions has made methanogens key contributors to biogeochemical cycles throughout most of Earth’s history. Most importantly, these oxygen-sensitive microorganisms have regulated the climate since the early Archean and impacted biogeochemical cycles throughout Earth’s history by producing the potent greenhouse gas, CH₄, while consuming H₂, CO₂, and small organic molecules. Hence, methanogens are attributed a key role in the start and end of several Proterozoic glaciations and mass extinction events. Their specific roles in the long-term carbon cycle that focus on CH₄ production are well-established, but, in contrast, only very few studies report on interactions with CaCO₃ and long-term carbon storage. Methanogens evolved early during Earth’s history, likely during the Archaean Eon, in layered benthic microbial communities called microbial mats. When lithified, these mats form microbialites that represent some of the earliest evidence of life in the fossil record, dating back >3.5 Gy. Methanogens are an integral part of contemporary microbial mats and have been identified both in the anoxic and oxic zones of these sedimentary ecosystems; however, their adaptations to apparently unfavorable oxic conditions and their role in the precipitation of carbonate in mats are unclear. In addition to an important role in the evolution of our planet by producing CH₄, methanogens may also produce a biosignature that could be relevant for astrobiology research. This review will discuss the diversity, physiology, and ecology of methanogens in detail to clarify their role in some of the major biogeochemical processes and ecological climatic events through the fluctuating environmental conditions on Earth through geologic time. Full article

This study presents a quantitative, scenario-based framework for analyzing humanity’s potential progression along the Kardashev scale, with emphasis on the transition to Type I (planetary-scale) and Type II (stellar-scale) civilization status. Using humanity as an empirical reference case, we integrate four coupled dimensions of civilizational development: energy utilization, information processing capacity, large-scale construction mass, and population dynamics, modeled through historical data, empirical trends, and physically motivated growth constraints. Energy availability is characterized using global energy production records and insolation statistics for potentially habitable exoplanets, explicitly acknowledging observational biases toward cooler host stars. Information processing growth is constrained by thermodynamic limits and observed trends in global data generation, while construction mass and population evolution are described using exponential and logistic growth models, respectively. These components are combined into a composite Civilization Development Index (CDI), a weighted logarithmic metric designed to track multi-scale civilizational advancement and tested through sensitivity analyses. Under optimistic assumptions of uninterrupted technological growth and absence of civilization-scale catastrophes, the framework suggests that humanity could reach Type I civilization status on the order of the 23rd century, while Type II status represents a substantially longer-term outcome extending into the third millennium or beyond. These timescales should be interpreted as lower bounds, as catastrophic events, sociopolitical constraints, or resource bottlenecks could significantly delay or prevent such transitions. By explicitly delineating assumptions, uncertainties, and physical constraints, this work provides a structured baseline for studies of long-term civilizational trajectories and the factors governing the emergence or absence of advanced technological civilizations. Full article

Recent findings demonstrate that concentrated sulfuric acid supports rich organic chemistry, including the stability of the canonical DNA bases adenine, thymine, guanine and cytosine. Yet, due to full protonation in concentrated sulfuric acid, these bases may not pair as effectively as they do in water. We are therefore motivated to study nucleic acid bases that pair via hydrophobic and van der Waals interactions instead of canonical hydrogen bonding. Here, we investigate the stability of 14 selected, commercially available alternative nucleobases in concentrated sulfuric acid to evaluate their potential for forming DNA-like polymers in this solvent. The reactivity of compounds 1–14 have not been previously investigated in concentrated sulfuric acid. We incubate the selected compounds in 98% and 81% w/w sulfuric acid and monitor their stability using ¹H and ¹³C NMR spectroscopy over 3 weeks at room temperature. In 98% w/w sulfuric acid, six bases—benzo[c][1,2,5]thiadiazole (1), 2,2′-bipyridine (2), 1,1′-biphenyl (3), 1-methoxy-3-methylbenzene (MMO2) (7) and 1-chloro-3-methoxybenzene (ClMO) (13), and 2,4-difluorotoluene (14)—remain soluble and stable with no detectable degradation. A few compounds show non-destructive reactivity, like sulfonation (compound 3) or H/D exchange (compounds 7, 13, 14). The other compounds react rapidly or are insoluble in 98% w/w sulfuric acid. In 81% w/w sulfuric acid, only compounds 1 and 2 remain stable and soluble, while other selected compounds are insoluble or unstable. Our findings identify a subset of alternative bases stable in concentrated sulfuric acid, advancing efforts towards the design of an example genetic-like polymer in this unusual solvent. Our work further highlights sulfuric acid’s potential for supporting complex organic chemistry, with implications for astrobiology, planetary science of Venus and synthetic biology. Full article

Since the dawn of civilization, humanity has looked to the sky, seeking to expand knowledge beyond Earth’s boundaries. The last eight decades have witnessed remarkable progress in space exploration, paving the way for increasingly longer space journeys and the establishment of human settlements on the Moon and Mars. These achievements have been made possible by advances in multiple scientific disciplines, including the rise of space medicine, astropharmacy, astrobiology, and astrobotany, each addressing how biological and technological systems adapt to extraterrestrial environments. Nevertheless, the space environment remains profoundly inhospitable to human life, making the protection of health and the assurance of long-term sustainability a key strategic goal in space exploration programs. Within this multidisciplinary framework, the potential role of medicinal plants remains underexplored. Historically central to healthcare, medicinal plants provide a vast repertoire of bioactive compounds and molecular scaffolds, many of which have inspired modern drugs. This review explores how medicinal plants could contribute to human well-being beyond Earth—not only as sources of therapeutic agents to mitigate spaceflight-induced ailments but also as biomanufacturing platforms for on-demand production of pharmaceuticals. Ultimately, medicinal plants could continue to play a pivotal role in supporting human health, also in space, but it poses new challenges and requires further scientific and technological advances. Full article

Ensuring a sustainable source of nutritious food is critical for long-duration space missions. Thai landrace rice 466HM exhibits high nutritional value and stress resilience, making it a promising candidate for space cultivation, yet its response to low Earth orbit (LEO) conditions remains poorly understood. This study compared rice grains maintained under terrestrial conditions with grains stored aboard the Shijian-19 (SJ-19) reusable satellite, orbiting at ~336 km for 13.5 days under microgravity (2⁻⁷ × 10⁻⁷g) and an absorbed radiation dose of ~0.153 rad (Si). Volatile compound profiling, texture analysis of cooked grains, and simulated gastrointestinal digestion followed by peptide mass fingerprinting were performed. LEO-exposed rice grains exhibited a 1.67-fold increase in adhesiveness compared to Earth-based rice (p < 0.01), while hardness remained unchanged between the two groups (p > 0.05), alongside distinct alterations in flavor-related volatile compounds and peptide profiles. Principal component analysis revealed clear separation between Earth and LEO-exposed samples, indicating microgravity-associated shifts in digestible peptide composition. Cytotoxicity assessment using MTT assays in HT-29 and HepG2 cells confirmed the safety of both rice types. These findings demonstrate that orbital conditions influence the compositional, functional, and sensory attributes of rice, providing insights relevant to space agriculture and astronaut nutrition. Full article

Space conditions offer new insights into fundamental biological and molecular mechanisms. The study aimed to evaluate the enzymatic activity of proteinase K (PK) under extreme conditions relevant to space environments: simulated microgravity, hypergravity, and gamma radiation. PK activity was tested using azocasein (AZO) as a chromogenic substrate, with enzymatic reactions monitored spectrophotometrically at 450 nm. A rotating wall vessel (RWV) simulated microgravity, centrifugation at 1000× g (3303 rpm) generated hypergravity, and gamma radiation exposure used cesium-137 as the ionizing source. PK activity showed no remarkable changes under microgravity after 16 or 48 h; however, higher absorbance values after 96 h indicated enhanced AZO proteolysis compared to 1 g (Earth gravity) controls. In hypergravity, low PK concentrations exhibited slightly increased activity, while higher concentrations led to reduced activity. Meanwhile, gamma radiation caused a dose-dependent decline in PK activity; samples exposed to deep-space equivalent doses showed reduced substrate degradation. PK retained enzymatic activity under all tested conditions, though the type and duration of stress modulated its efficiency. The results suggest that enzyme-based systems may remain functional during space missions and, in some cases, exhibit enhanced activity. Nevertheless, their behavior must be evaluated in a context-dependent manner. These findings may be significant to advance biotechnology, diagnostics, and the development of enzyme systems for space applications. Full article

Melanin pigments are ubiquitous biopolymers across diverse life forms and play multifaceted roles in cellular defense and environmental adaptation. The specialized neuromelanin in human brains accumulates mainly within catecholaminergic neurons of the substantia nigra and locus coeruleus, serving as a crucial modulator of brain homeostasis, metal detoxification, and oxidative stress responses. The intricate processes of human melanogenesis, encompassing both cutaneous and neuronal forms, are governed by complex genetic networks. Concurrently, melanin in fungi (synthesized through distinct genetic pathways) confers remarkable resistance to environmental stressors, including ionizing radiation. Recent advancements in omics technologies—including transcriptomics, proteomics, metabolomics, and epigenomics—have profoundly enhanced our understanding of neuromelanin’s molecular environment in health, aging, and neurodegenerative conditions such as Parkinson’s disease (PD), Alzheimer’s disease (AD), and other neurological disorders. This article reviews the genetic underpinnings of human melanogenesis and fungal melanogenesis, explores the convergent and divergent evolutionary pressures driving their functions, and synthesizes the rapidly accumulating omics data to elucidate neuromelanin’s critical, and often dual, role in human brain pathology. Moreover, we discuss the intriguing parallels between neuromelanin and fungal melanin, highlighting radioprotection and its potential implications for neuroprotection and astrobiology, with a special emphasis on the need to investigate neuromelanin’s potential for radioprotection in light of fungal melanin’s remarkable protective properties. Full article

Propylene oxide is the first and only chiral molecule to have been observed in the interstellar medium. Given the mechanisms for forming chiral species, which are important for astrobiology in understanding the origins of life, we report here an experimental and theoretical investigation into the electronic structure of propylene oxide and its evolution from the methylation and epoxidation of ethene. Here, electron momentum spectroscopy is used as an orbital-imaging technique to probe experimental orbital momentum distributions. These are directly compared with theoretical orbital momentum distributions calculated at the equilibrium geometry, and those calculated by considering the vibrational motion of the propylene oxide target. This allows us to identify which molecular orbitals are sensitive to specific vibrational normal modes, thereby facilitating understanding and controlling chemical reactivity. By extending our investigation to include intermediate species along the evolution of ethene through methylation and epoxidation, we can develop an understanding of how the orbital electronic structure evolves through this series of important chemicals. Full article

Following recommendations from the 2023–2032 Planetary Science and Astrobiology Decadal Survey, we propose a novel Uranus exploration mission that is centered on using constellations of small spacecraft to observe the Uranus system. Using the method of patched conics and system-level design, we present a Pre-Phase A mission concept to launch a 4500 kg spacecraft on a Jupiter–Uranus gravity assist transfer trajectory with a transfer time of six years, having the spacecraft arrive at Uranus in 2039 after launching in 2033. To maintain the quality of data collection while minimizing mass, we propose that the spacecraft will be composed of a carrier spacecraft with a 3848 kg wet mass, which would be used primarily for communications and orbital transfers, and a constellation of CubeSats with a combined wet mass of 640 kg, which would house the instrumentation. In this paper, we discuss the feasibility of the proposed mission concept and we demonstrate that a CubeSat constellation mission to Uranus can be not only viable but also a fuel and cruise time optimization opportunity, delivering 16 exploration spacecraft to Uranus in six years. Full article

A high-level ab initio characterization and formation of diaminomethane (DAM), the simplest geminal diamine, is presented to support its spectroscopic detection and astrochemical relevance in the interstellar medium. The C_2v DAM conformer is identified as the global minimum, while C₁ DAM and C₂ DAM represent higher-energy local minima. The proposed reaction pathways are exothermic and proceed without activation barriers. Simulated infrared spectrum reproduces accurate key spectral signatures with several vibrational modes exhibiting strong IR intensities (>80 km mol⁻¹), particularly in the 800–3000 cm⁻¹ range and band shapes. Dipole moments and accurate rovibrational spectroscopic parameters, including rotational constants, anharmonic vibrational frequencies, quartic and sextic distortion constants, and nuclear quadrupole coupling constants are reported to assist with high-resolution spectroscopic identification. This study provides significant theoretical benchmarks for its formation and offers guidance for future laboratory spectroscopy and molecular searches in interstellar environments. Full article

One key objective of astrobiology is to investigate and discover if other planetary bodies are habitable. The determination of whether an environment is habitable to known life requires measuring liquid water, CHNOPS elements, other nutrients, and energy supplies. Here we investigate the potential for a single instrument capable of sampling these key indicators: a ‘Total Habitability Instrument’. The proposed instrument would be capable of deployment in diverse environments and provide an integrated set of measurements that together allow for the assessment of the habitability of an environment of interest, such as those of the Moon or Mars. We explore existing and potential technological developments that would enable the construction of such an instrument, with a focus on soft systems, which are inspired by nature in their design, and microfluidics. This paper considers a multidisciplinary approach to the design and sensing requirements of a Total Habitability Instrument that would be capable of gathering and processing samples and be deployable by both robotic and human explorers on all planetary bodies, allowing for the mapping of habitability over large areas of our Solar System and beyond. Full article

Soil contamination is a major contemporary issue. In light of increasing efforts to align seedling production with the sustainable use and preservation of soil resources, this study aimed to explore the potential of selected plant-growth-promoting bacteria as natural alternatives to mineral fertilizers, a major soil pollutant in the forestry sector. The experiment involved inoculating one-year-old sessile oak (Quercus petraea) seedlings with multiple single bacterial treatments and a consortia derived from sessile oak rhizosphere and monitoring their effects on plant physiological parameters such as chlorophyll, carotenoid, and nitrogen content, along with selected parameters of the rapid chlorophyll a fluorescence induction curve (an OJIP curve). The results indicated that the selected bacterial strains improved specific plant physiological parameters at certain points during the monitoring period; however, further research is necessary to draw statistically significant conclusions. Although these bacteria did not directly enhance photosynthetic parameters, their potential remains evident and could be harnessed through improved application methods. Future studies should focus on identifying site conditions that support the proliferation of the introduced bacterial populations. Full article

Cells of Serratia liquefaciens were grown on trypticase soy agar (TSA) for 28 d under Martian conditions of 7 mbar, 0 °C, and CO₂-enriched anoxic atmospheres (called Mars low-PTA conditions). Earth controls were maintained for 24 h at 1013 mbar, 30 °C, and a standard pN₂/pO₂ gas composition. Cells were harvested at either 24 h or 28 d from TSA surfaces and processed for SEM and TEM imaging. Cells of S. liquefaciens grown under Earth conditions were uniform in shape and size, averaging approximately 1.25 µm in length and 0.5 µm in width. Fimbriae were observed on 10–20% of cells grown under Earth conditions. Key features of low-PTA grown cultures were (1) cells exhibited swollen blunt ends at sites of cell division tapering to unusually constricted points on the distal ends of progeny cells, (2) cell division appeared disrupted with division planes occurring at odd angles often forming right-angle oriented daughter cells, (3) some cells failed to form divisional planes resulting in long spiral and oddly shaped cells measuring up to 6–8 µm in length, and (4) fimbriae were lacking. Cell walls were found to be approx. 17% thinner when cells were grown in low-PTA environments compared to lab-standard conditions. Full article

Unidentified Anomalous Phenomena (UAP) observations have been reported from ancient times to today, but their true nature remains uncertain. In this paper we propose a rating scale designed to separate “signal” from “noise” in assessing UAP sighting reports. Our intention is that this will help professionals and laypeople alike distinguish cases that warrant further investigation from easily explainable false alarms. We categorize UAP sighting reports according to the quality of their evidence, considering such factors as number of observers, amount and quality of supporting evidence, especially physical evidence, and perhaps most importantly, whether UAP witnesses have made some effort to find an ordinary explanation for what they saw or experienced and whether the evidence has been subject to expert analysis. Full article