About this Research Topic
In the quest to know whether extraterrestrial life exists elsewhere in the universe, it is critical to be able to distinguish abiotic signatures from biomediated signatures. However, we have few standards for truly abiotic environmental processes, and our perspective is overwhelmed by an “Earth bias” in which every near-surface nook and cranny has been exploited by life. The question stands: Do we even know what an “abiotic” habitable planet would look like?
New challenges in astrobiology require that the science community clarifies what constitutes a biosignature, whether from extant or past life. Biosignatures are similar to the biomarkers used in medical fields, although often in the geological record the original physical evidence of life may be altered, degraded, obscured, or missing. In particular, most sedimentary processes at the Earth’s surface are mediated (passively or actively) by microbial communities that are present in the different stages of sediment burial and formation. Microbially-mediated dissolution, precipitation, and transformation of minerals are either directly controlled by microorganisms or induced by biochemical reactions that take place outside the cell or the community. Some rocks appear to lack biosignatures until examined at extremely high magnification. This underscores the importance of determining reliable biosignature criteria across multiple nested scales and in context. Studies can include effects of microbial communities on sedimentary archives with small-scale approaches involving organic matter characterization (biomarkers), isotope biogeochemistry and “-omics” methods, up to larger-scale approaches involving the context of water-rock-biota interactions. Additional studies utilize chemical experiments to better establish abiotic standards.
The issue of differentiating biological from abiologically mediated processes is a core scientific question that is enhanced by the development of new, highly interdisciplinary research approaches and current technologies: higher resolution elemental, isotopic, and mineral imaging and detection; planetary exploration via orbiting and landed spacecraft; and emerging cyberinfrastructure databases and visualization tools. This Research Topic aims to better constrain the interdependency between the physical-chemical planetary processes and biological evolution across a range of timescales. A goal of the proposed volume is to address the origin, structure and evolution of Earth-like planets, and to identify the best approaches to detect biosignatures and organics in planetary systems. Understanding the interplay between life and its planetary environment on Earth will allow for a more informed search for life on other planets. Understanding the origin of life on Earth will answer a very profound question that resonates strongly with the general public: “Where do we all come from?”. We welcome contributions covering these challenging topics.
This stimulating Research Topic demands collaborations across traditional research areas of earth science, biology, chemistry, planetary science, mathematical approaches, and astronomy, in order to establish a long-term, cross-disciplinary network of excellent scientists all over the world. Thus, the combination of the driving questions of life origins with new technologies and collaborative approaches will surely advance the expanding field of astrobiology.
Keywords: search for life, planets, biosignatures, biomarker, chemical reactions
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.