RNA World

Ayukawa, Shotaro; Enomoto, Toshihiko; Kiga, Daisuke

doi:10.1007/978-981-13-3639-3_6

Cited by 5 publications

(3 citation statements)

References 41 publications

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“…Abiotic nucleic acids have never been detected in natural environments; however, experiments suggest that nucleic acids could be synthesized in these environments [26].…”

Section: Nuclear Acidsmentioning

confidence: 99%

Comparative study of methods for finding extraterrestrial life based on solar system exploration and the role of microscopy in it

Enya¹,

Ymagishi²,

Kobayashi³

et al. 2023

SPIE Future Sensing Technologies 2023

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We present a comparative study of methods with a table summarizing them in searching extraterrestrial life. This work represents an update and improvement of our previous publication. In these works, microorganisms are supposed to be the object of extraterrestrial life exploration. We selected several characteristics and molecules which can be detected and analyzed in searching for extraterrestrial life. We also evaluated the search technique which targets those characteristics and molecules from several points of view. In this revision, “Generality for terrestrial microorganism” and “Source of false positives” were resolved into sub-issues and described in detail. We also introduced new issues, i.e., “Possible meaning of negative detection” and “Science objectives other than life search.” We classified life in space into three types: Earth life, Earth-independent life (life that emerged from non-life independently of Earth life), and Earth-kin life (extraterrestrial life sharing a common ancestor life with Earth life). All the methods which are effective in detecting Earth life are potentially useful for the detection of Earth-kin life. In contrast, their applicability is not guaranteed for Earth-independent life. The three major conclusions of the previous article were re-evaluated and confirmed to remain unchanged: (i) there is no realistic single detection method which can conclude on the discovery of life independent of Earth, (ii) there is no single best method which is superior to the other methods in all respects, and (iii) there is no single method which can distinguish between Earth life and life independent of Earth. Subsequently, we discussed the combination of the detection methods and dividing extraterrestrial microorganism search into multiple steps: the survey and- detection step and the analysis-and-conclusion step. We also emphasized the importance of imaging; even with not enough resolution for observing the detailed morphology of a microbial cell, it is highly worthwhile to distinguish whether the detected molecules are concentrated at micron size or diffused thinly. Of course, high-resolution imaging provides information with regard to the morphology of microorganisms. Accordingly, imaging is necessary for both the survey-and-detection and the analysis-and-conclusion steps. To realize a space exploration mission or instrument for extraterrestrial life search, not only in scientific but programmatic sense, it is important to design it so that scientific results can be obtained even if no life is found. The studies included in this article primarily supposed Mars as a target; however, they are valid for a wide variety of planets of the solar system, as well as their moons and small objects.

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“…Abiotic nucleic acids have never been detected in natural environments; however, experiments suggest that nucleic acids could be synthesized in these environments [26].…”

Section: Nuclear Acidsmentioning

confidence: 99%

Comparative study of methods for finding extraterrestrial life based on solar system exploration and the role of microscopy in it

Enya¹,

Ymagishi²,

Kobayashi³

et al. 2023

SPIE Future Sensing Technologies 2023

View full text Add to dashboard Cite

show abstract

“…Abiotic nucleic acids have never been detected in natural environments. However, laboratory experiments suggest that abiotic synthesis of nucleic acids could exist (Ayukawa et al ., 2019 ). The possibility of a nonbiological origin should, therefore, be considered.…”

Section: Targeted Characteristics and Detection Techniquesmentioning

confidence: 99%

A Comparative Study of Methods for Detecting Extraterrestrial Life in Exploration Missions to Mars and the Solar System II: Targeted Characteristics, Detection Techniques, and Their Combination for Survey, Detection, and Analysis

Enya,

Yamagishi,

Kobayashi

et al. 2023

Astrobiology

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We present a comparative study of the methods used in the search for extraterrestrial microorganism life, including a summary table where different life-detection techniques can be easily compared as an aid to mission and instrument design aimed at life detection. This is an extension of previous study, where detection techniques for a series of target characteristics and molecules that could constitute a positive life detection were evaluated. This comparison has been extended with a particular consideration to sources of false positives, the causes of negative detection, the results of detection techniques when presented regarding terrestrial life, and additional science objectives that could be achieved outside the primary aim of detecting life. These additions address both the scientific and programmatic side of exploration mission design, where a successful proposal must demonstrate probable outcomes and be able to return valuable results even if no life is found. The applicability of the life detection techniques is considered for Earth life, Earth-independent life (life emerging independently from that on Earth,) and Earth-kin life (sharing a common ancestor with life on Earth), and techniques effective in detecting Earth life should also be useful in the detection of Earth-kin life. However, their applicability is not guaranteed for Earth-independent life. As found in our previous study, there exists no realistic single detection method that can conclusively determine the discovery of extraterrestrial life, and no method is superior to all others. In this study, we further consider combinations of detection techniques and identify imaging as a valuable addition to molecule detection methods, even in cases where there is insufficient resolution to observe the detailed morphology of a microbial cell. The search for extraterrestrial life is further divided into a survey-and-detection and analysis-and-conclusion step. These steps benefit from different detection techniques, but imaging is necessary for both parts.

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“…For instance, which was first: Proteins or nucleic acids? The consensus is that nucleic acids were probably the first biomolecules, specifically RNA in what is commonly known as the “RNA world hypothesis” ( Cech, 2012 ; Gesteland et al, 1999 ), since RNA is both a catalyst and a repository of genetic information making it candidate for the first biopolymers ( Ayukawa et al, 2019 ; Neveu et al, 2013 ; Orgel, 2004 ).…”

Section: Introductionmentioning

confidence: 99%