In search of the RNA world on Mars

Mojarro, Angel; Lin, Jin; Szostak, Jack W.; Head, J. W.; Zuber, M. T.

doi:10.1111/gbi.12433

Cited by 15 publications

(17 citation statements)

References 133 publications

(259 reference statements)

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“…Alternately, the detection of remnants of ferrocyanide-rich environments on Mars ( e.g. , ferrocyanide salt deposits) might inform our understanding of the prevalence of such systems on early Earth (Sasselov et al , 2020 ; Mojarro et al , 2021 ).…”

Section: Discussionmentioning

confidence: 99%

UV Transmission in Natural Waters on Prebiotic Earth

et al. 2021

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Ultraviolet (UV) light plays a key role in surficial theories of the origin of life, and numerous studies have focused on constraining the atmospheric transmission of UV radiation on early Earth. However, the UV transmission of the natural waters in which origins-of-life chemistry (prebiotic chemistry) is postulated to have occurred is poorly constrained. In this work, we combine laboratory and literature-derived absorption spectra of potential aqueous-phase prebiotic UV absorbers with literature estimates of their concentrations on early Earth to constrain the prebiotic UV environment in marine and terrestrial natural waters, and we consider the implications for prebiotic chemistry. We find that prebiotic freshwaters were largely transparent in the UV, contrary to assumptions in some models of prebiotic chemistry. Some waters, such as high-salinity waters like carbonate lakes, may be deficient in shortwave (≤220 nm) UV flux. More dramatically, ferrous waters can be strongly UV-shielded, particularly if the Fe 2+ forms highly UV-absorbent species such as . Such waters may be compelling venues for UV-averse origin-of-life scenarios but are unfavorable for some UV-dependent prebiotic chemistries. UV light can trigger photochemistry even if attenuated through photochemical transformations of the absorber ( e.g. , production from halide irradiation), which may have both constructive and destructive effects for prebiotic syntheses. Prebiotic chemistries that invoke waters that contain such absorbers must self-consistently account for the chemical effects of these transformations. The speciation and abundance of Fe 2+ in natural waters on early Earth is a major uncertainty and should be prioritized for further investigation, as it played a major role in UV transmission in prebiotic natural waters.

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Section: Discussionmentioning

confidence: 99%

UV Transmission in Natural Waters on Prebiotic Earth

et al. 2021

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“…Criouet et al (2021) infer from previous experimental work on hydrochar that further diagenetic alteration of these structures could render them hollow and thus even more similar to fossil bacteria. The viability of an RNA world on early Mars has been exploredand broadly supportedin light of geochemical considerations (Mojarro et al 2021), but, in any case, similar spheroids can very probably result from many other organic precursors. Indeed, similarly robust hollow hydrocarbon spheroids <1-50 μm in diameter were recovered from deep groundwater in the Witwatersrand Basin of South Africa, where they appear to have formed through the abiotic reorganization of thermally altered (ultimately biogenic) organic matter (Wanger et al 2012).…”

Section: Other Organic Biomorphsmentioning

confidence: 99%

False biosignatures on Mars: anticipating ambiguity

McMahon

Cosmidis

2021

JGS

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It is often acknowledged that the search for life on Mars might produce false positive results, particularly via the detection of objects, patterns or substances that resemble the products of life in some way but are not biogenic. The success of major current and forthcoming rover missions now calls for significant efforts to mitigate this risk. Here, we review known processes that could have generated false biosignatures on early Mars. These examples are known largely from serendipitous discoveries rather than systematic research and remain poorly understood; they probably represent only a small subset of relevant phenomena. These phenomena tend to be driven by kinetic processes far from thermodynamic equilibrium, often in the presence of liquid water and organic matter, conditions similar to those that can actually give rise to, and support, life. We propose that strategies for assessing candidate biosignatures on Mars could be improved by new knowledge on the physics and chemistry of abiotic self-organization in geological systems. We conclude by calling for new interdisciplinary research to determine how false biosignatures may arise, focusing on geological materials, conditions and spatiotemporal scales relevant to the detection of life on Mars, as well as the early Earth and other planetary bodies.Thematic collection: This article is part of the Astrobiology: Perspectives from the Geology of Earth and the Solar System collection available at: https://www.lyellcollection.org/cc/astrobiology-perspectives-from-geology-of-earth-and-solar-system

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“…Because of the multitude of biochemicals that make up a living system, it is envisioned that ponds and streams must undergo changes that bring together different ingredients. Although most PCE experiments are conducted at circumneutral pH, there are some which benefit or begin from a more acidic, or more basic, environment [14,33]. RNA stability increases with acidic pH and with Mg 2+ rather than Fe 2+ in solution [16].…”

Section: Planetary Settingsmentioning

confidence: 99%

“…Could life have arisen on Mars? [9][10][11][12][13][14][15][16]. A hallmark of a biosphere of Life is its ability to adapt its forms such that it has species and strains of organisms which variously are able to survive and even sometimes prosper in nearly all conceivable aqueous environments.…”

Section: Introductionmentioning

confidence: 99%

Origin of Life on Mars: Suitability and Opportunities

Clark

Kolb

Steele

et al. 2021

Life

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Although the habitability of early Mars is now well established, its suitability for conditions favorable to an independent origin of life (OoL) has been less certain. With continued exploration, evidence has mounted for a widespread diversity of physical and chemical conditions on Mars that mimic those variously hypothesized as settings in which life first arose on Earth. Mars has also provided water, energy sources, CHNOPS elements, critical catalytic transition metal elements, as well as B, Mg, Ca, Na and K, all of which are elements associated with life as we know it. With its highly favorable sulfur abundance and land/ocean ratio, early wet Mars remains a prime candidate for its own OoL, in many respects superior to Earth. The relatively well-preserved ancient surface of planet Mars helps inform the range of possible analogous conditions during the now-obliterated history of early Earth. Continued exploration of Mars also contributes to the understanding of the opportunities for settings enabling an OoL on exoplanets. Favoring geochemical sediment samples for eventual return to Earth will enhance assessments of the likelihood of a Martian OoL.

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In search of the RNA world on Mars

Cited by 15 publications

References 133 publications

UV Transmission in Natural Waters on Prebiotic Earth

UV Transmission in Natural Waters on Prebiotic Earth

False biosignatures on Mars: anticipating ambiguity

Origin of Life on Mars: Suitability and Opportunities

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