Redefining Life: Integrating Biology, Chemistry, and Planetary Science in Modern Astrobiology

Redefining Life: Integrating Biology, Chemistry, and Planetary Science in Modern Astrobiology

JelangJelku D. Sangma^1,2,3

¹Department of Food Science and Nutrition, University of Agricultural Sciences, GKVK, Bangalore, Karnataka, 560065, India

²AICRP-WIA, ICAR (CIWA), Bhubaneswar, College of Community Science, Central Agricultural University, Tura, Meghalaya - 794005, India

³Eudoxia Research University, 256 Chapman Road STE 105-4, New Castle, USA

Corresponding Author Email: jelang.jelku3@gmail.com

DOI : https://doi.org/10.51470/CHE.2026.07.01.01

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1. Introduction

For centuries, life was assumed to be a uniquely Earth-bound phenomenon. Biological sciences developed under the assumption that terrestrial life forms represented universal biological principles. However, modern discoveries in microbiology, planetary science, and astrochemistry challenge this assumption. Organisms thriving in deep oceans, acidic lakes, frozen deserts, and radioactive environments demonstrate that life adapts far beyond previously assumed limits [1]. Astrobiology now seeks to understand life as a cosmic phenomenon rather than a planetary exception. The discipline combines biology, chemistry, geology, astronomy, and planetary science to explore how life emerges, survives, and evolves in diverse environments. Discoveries of organic molecules in meteorites, water reservoirs on distant planetary bodies, and potentially habitable exoplanets have significantly expanded the scope of this field [2]. Modern astrobiology must therefore reconsider fundamental questions: What defines life? Can life exist with chemistries different from Earth’s? Are biological processes universal or Earth-specific? Addressing these questions requires integrating multiple scientific domains to construct a broader framework for life detection and interpretation.

2. Historical Perspective on the Definition of Life

Traditional definitions describe life as systems capable of metabolism, growth, reproduction, and evolution. These criteria function well for Earth organisms but become problematic in boundary cases such as viruses, prions, or artificial life systems.Viruses, for instance, lack independent metabolism yet evolve and replicate within host cells. Dormant spores may remain inactive for millennia but still qualify as living once reactivated. Synthetic biology further complicates definitions as researchers create artificial cells and genetic systems with life-like properties.Astrobiology challenges definitions further by considering non-terrestrial possibilities. Life elsewhere may not use DNA, proteins, or even water as solvents [3]. Thus, defining life strictly based on terrestrial biology risks overlooking unfamiliar but functional life systems, modern perspectives increasingly define life as self-sustaining chemical systems capable of Darwinian evolution. This broader framework accommodates both Earth life and hypothetical alternative biological systems.

3. Chemical Foundations of Life

Chemistry forms the bridge between non-living matter and biological systems. Understanding how simple molecules transition into complex biological structures remains central to astrobiology.Prebiotic chemistry research shows that amino acids, nucleotides, and lipid precursors can form under conditions resembling early planetary environments. Laboratory simulations demonstrate that energy sources such as lightning, ultraviolet radiation, hydrothermal activity, and meteorite impacts can drive organic synthesis.Meteorites and interstellar clouds contain complex organic compounds, suggesting that organic chemistry is widespread in the universe. These findings support the hypothesis that life’s building blocks may naturally arise wherever suitable conditions exist.Important questions remain regarding how molecular systems achieve self-replication, compartmentalization, and metabolism [4]. Competing hypotheses propose RNA-first models, metabolism-first pathways, or lipid world scenarios, each suggesting alternative routes toward biological complexity.Understanding these chemical processes helps identify planetary environments where life could potentially originate.

4. Planetary Environments and Habitability

Habitability traditionally focused on the circumstellar “habitable zone,” where liquid water can exist on planetary surfaces. However, discoveries within our own solar system suggest that habitable environments may exist beyond this narrow definition [5]. Subsurface oceans beneath icy crusts, hydrothermal systems, and underground reservoirs may sustain microbial ecosystems shielded from hostile surface conditions. Such environments expand the concept of habitability to include worlds far from their stars.

Factors influencing planetary habitability include:

• Availability of liquid solvents
• Energy sources for metabolism
• Chemical nutrients
• Environmental stability
• Protection from harmful radiation

Planetary atmospheres, geological activity, and magnetic fields influence long-term biological potential. Exoplanet observations increasingly reveal worlds with varied compositions, raising the possibility of life in environments unlike Earth.

5. Extremophiles and Expanding Biological Limits

Research on extremophiles—organisms thriving in extreme environments—has profoundly reshaped our understanding of life’s resilience. Microbes have been discovered in environments characterized by high temperature, extreme acidity, intense pressure, salinity, or radiation.These organisms demonstrate that life adapts to conditions once thought incompatible with biology. Some microbes survive deep underground without sunlight, relying entirely on chemical energy sources. Others persist in frozen or highly saline conditions [6].Such discoveries imply that extra-terrestrial environments previously dismissed as sterile may indeed support life. Studying extremophiles therefore provides models for potential extra-terrestrial ecosystems.

6. Biosignatures and Life Detection Strategies

Detecting extra-terrestrial life requires identifying reliable biosignatures—indicators of biological activity. These may include atmospheric gases, chemical imbalances, mineral structures, or molecular patterns unlikely to arise through non-biological processes.

Potential biosignatures include:

• Oxygen-methane disequilibrium in planetary atmospheres
• Organic molecular complexity
• Microfossil structures
• Isotopic fractionation patterns
• Surface pigments or biological textures

Abiotic processes may mimic biological signals, complicating interpretation. Modern astrobiology therefore emphasizes multiple lines of evidence before claiming biological detection [7]. Future missions aim to analyze planetary atmospheres, surface chemistry, and subsurface samples to improve biosignature identification.

7. Emerging Technologies in Astrobiology

Technological advances enable increasingly sophisticated exploration strategies. Modern astrobiology benefits from:

• High-resolution space telescopes detecting exoplanet atmospheres
• Robotic planetary missions conducting in-situ analysis
• Miniaturized life-detection instruments
• AI-driven data analysis
• Advanced molecular sequencing tools

Sample return missions and autonomous planetary probes promise unprecedented insights into planetary chemistry and potential biosignatures. Simultaneously, laboratory research simulates extra-terrestrial conditions to test biological survival limits.Technological innovation remains central to discovering life beyond Earth.

8. Philosophical and Scientific Implications

Redefining life carries profound philosophical and scientific implications. Discovering alternative life forms would challenge assumptions about biology, evolution, and humanity’s place in the universe [8]. Even without extraterrestrial discovery, astrobiology transforms biology into a planetary and cosmic science, emphasizing life’s adaptability and interconnectedness with environmental systems. This interdisciplinary field also influences climate science, planetary protection policies, and future human space exploration strategies.

9. Future Directions in Astrobiology Research

Future astrobiology research will focus on integrating planetary exploration, laboratory simulations, and theoretical modeling. Key goals include refining biosignature detection, understanding prebiotic chemistry pathways, and assessing planetary habitability across diverse environments.Interdisciplinary collaboration between molecular biologists, chemists, planetary scientists, and astronomers will be essential. Advances in synthetic biology may also help construct experimental life models to test hypotheses about alternative biological systems [9]. As exploration technologies improve, humanity moves closer to answering one of science’s most profound questions: Is life unique to Earth, or is it a universal phenomenon?

10. Conclusion

Modern astrobiology is redefining life by integrating biology, chemistry, and planetary science into a unified framework. Discoveries of extremophiles, organic chemistry in space, and potentially habitable planetary environments demonstrate that life may arise and persist under conditions far broader than once assumed. An expanding definitions of life and developing new detection strategies, astrobiology transforms our understanding of biology from a planet-centered science into a universal inquiry. An interdisciplinary research and technological progress promise to reveal whether life exists elsewhere, ultimately reshaping humanity’s understanding of its place in the cosmos.

References

1. Knuuttila, T., &Loettgers, A. (2017). What are definitions of life good for? Transdisciplinary and other definitions in astrobiology. Biology & Philosophy, 32(6), 1185-1203.
2. National Academies of Sciences, Medicine, Division on Engineering, Physical Sciences, Space Studies Board, & Committee on Astrobiology Science Strategy for the Search for Life in the Universe. (2019). An Astrobiology Strategy for the Search for Life in the Universe. National Academies Press.
3. Cottin, Hervé, Julia Michelle Kotler, Kristin Bartik, H. James Cleaves, Charles S. Cockell, Jean-Pierre P. De Vera, Pascale Ehrenfreund et al. “Astrobiology and the possibility of life on earth and elsewhere….” Space Science Reviews 209, no. 1 (2017): 1-42.
4. Santos, C. M. D., Alabi, L. P., Friaça, A. C., & Galante, D. (2016). On the parallels between cosmology and astrobiology: a transdisciplinary approach to the search for extraterrestrial life. International Journal of Astrobiology, 15(4), 251-260.
5. Frank, A., Kleidon, A., & Alberti, M. (2017). Earth as a hybrid planet: the Anthropocene in an evolutionary astrobiological context. Anthropocene, 19, 13-21.
6. Caporael, L. R. (2018). Astrobiology as Hybrid Science: Introduction to the Thematic Issue. Biological Theory, 13(2), 69-75.
7. Forde, V. (2024). Astrophysical Preservation of Terrestrial Life on Mars Through a Sphericalist, Esoteric Futurist Approach (Doctoral dissertation, Liverpool John Moores University (United Kingdom)).
8. Dick, S. J. (2020). Critical issues in the history, philosophy, and sociology of astrobiology. In Space, time, and aliens: collected works on cosmos and culture (pp. 655-693). Cham: Springer International Publishing.
9. Visconti, G. (2021). Astrobiology and development of human civilization. In Climate, Planetary and Evolutionary Sciences: A Machine-Generated Literature Overview (pp. 215-261). Cham: Springer International Publishing.
10. Amilburu, A., Moreno, Á., & Ruiz-Mirazo, K. (2021). Definitions of life as epistemic tools that reflect and foster the advance of biological knowledge. Synthese, 198(11), 10565-10585.

Dr. JelangJelku D. Sangma did schooling from St. Mary’s School, Tura. Class 12 Science, St. Mary’s College, Shillong, and B.Sc. Community Science from College Community Science, Central Agricultural University (Imphal), Tura, Meghalaya. Secured an ICAR seat for M.Sc. at Professor Jayashankar Telangana State Agricultural University, Hyderabad, and an ICAR seat for Ph.D. at the University of Agricultural Sciences, GKVK, Bangalore. Recipient of UGC NET JRF, cleared ASRB NET. “Development of Foxtail malt mix” got selected for Dr. APJ Abdul Kalam, Best Innovation Award category in the 24th World Congress on Clinical Nutrition with 1st Congress on Medical Food and Nutrition in 2021. International Innovation Program for Post-Doctoral Fellow, Eudoxia Research University, USA and India. ID No.: ERU/IIP-PDF/REG/2024/293. Worked as Young Professional II, AICRP-WIA ICAR (CIWA), Bhubaneswar at College of Community Science, Central Agricultural University (Imphal), Tura, Meghalaya for a period of 1 year.