Caveats to Exogenous Organic Delivery from Ablation, Dilution, and Thermal Degradation

Mehta, Chris; Perez, Anthony; Thompson, Glenn; Pasek, Matthew A.

doi:10.3390/life8020013

Cited by 18 publications

(14 citation statements)

References 49 publications

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“…not sufficiently large to protect gases from escaping the mineral matrix (Sears 1975;Shingledecker 2014;Mehta et al 2018). Additionally, it could be possible that the Aguas Zarcas meteorite chip we obtained for this work was from a more degassed portion of the Aguas Zarcas parent body.…”

Section: Abundance and Molecular Distribution Of Carbonyl Compoundsmentioning

confidence: 99%

Extraterrestrial organic compounds and cyanide in the CM2 carbonaceous chondrites Aguas Zarcas and Murchison

Aponte

Simkus

Elsila

et al. 2020

Meteorit & Planetary Scien

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Evaluating the water‐soluble organic composition of carbonaceous chondrites is key to understanding the inventory of organic matter present at the origins of the solar system and the subsequent processes that took place inside asteroid parent bodies. Here, we present a side‐by‐side analysis and comparison of the abundance and molecular distribution of aliphatic amines, aldehydes, ketones, mono‐ and dicarboxylic acids, and free and acid‐releasable cyanide species in the CM2 chondrites Aguas Zarcas and Murchison. The Aguas Zarcas meteorite is a recent fall that occurred in central Costa Rica and constitutes the largest recovered mass of a CM‐type meteorite after Murchison. The overall content of organic species we investigated was systematically higher in Murchison than in Aguas Zarcas. Similar to previous meteoritic organic studies, carboxylic acids were one to two orders of magnitude more abundant than other soluble organic compound classes investigated in both meteorite samples. We did not identify free cyanide in Aguas Zarcas and Murchison; however, cyanide species analyzed after acid digestion of the water‐extracted meteorite mineral matrix were detected and quantified at slightly higher abundances in Aguas Zarcas compared to Murchison. Although there were differences in the total abundances of specific compound classes, these two carbonaceous chondrites showed similar isomeric distributions of aliphatic amines and carboxylic acids, with common traits such as a complete suite of structural isomers that decreases in concentration with increasing molecular weight. These observations agree with their petrologic CM type‐2 classification, suggesting that these meteorites experienced similar organic formation processes and/or conditions during parent body aqueous alteration.

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Section: Abundance and Molecular Distribution Of Carbonyl Compoundsmentioning

confidence: 99%

Extraterrestrial organic compounds and cyanide in the CM2 carbonaceous chondrites Aguas Zarcas and Murchison

Aponte

Simkus

Elsila

et al. 2020

Meteorit & Planetary Scien

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show abstract

“…The infall of carbonaceous meteorites and their associated organic compounds could have also contributed prebiotic compounds to the early oceans. But the survival of extraterrestrial organic molecules, mainly in the form of interplanetary dust particles (IDPs), during atmospheric passage and heating is a major concern [10,11]. As was the case with prebiotic compounds made directly on Earth, oceanic extraterrestrial compounds accumulation could have been limited by hydrothermal circulation if it existed.…”

Section: Introductionmentioning

confidence: 99%

Exposed Areas Above Sea Level on Earth >3.5 Gyr Ago: Implications for Prebiotic and Primitive Biotic Chemistry

Bada

Korenaga

2018

Life

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How life began on Earth is still largely shrouded in mystery. One of the central ideas for various origins of life scenarios is Darwin’s “warm little pond”. In these small bodies of water, simple prebiotic compounds such as amino acids, nucleobases, and so on, were produced from reagents such as hydrogen cyanide and aldehydes/ketones. These simple prebiotic compounds underwent further reactions, producing more complex molecules. The process of chemical evolution would have produced increasingly complex molecules, eventually yielding a molecule with the properties of information storage and replication prone to random mutations, the hallmark of both the origin of life and evolution. However, there is one problematic issue with this scenario: On the Earth >3.5 Gyr ago there would have likely been no exposed continental crust above sea level. The only land areas that protruded out of the oceans would have been associated with hotspot volcanic islands, such as the Hawaiian island chain today. On these long-lived islands, in association with reduced gas-rich eruptions accompanied by intense volcanic lightning, prebiotic reagents would have been produced that accumulated in warm or cool little ponds and lakes on the volcano flanks. During seasonal wet–dry cycles, molecules with increasing complexity could have been produced. These islands would have thus been the most likely places for chemical evolution and the processes associated with the origin of life. The islands would eventually be eroded away and their chemical evolution products would have been released into the oceans where Darwinian evolution ultimately produced the biochemistry associated with all life on Earth today.

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“…Atmospheric entry of bolides, however, can have deleterious effects on bolide size and composition. Hills and Goda (1993) demonstrated that large objects ablate as they decelerate through the atmosphere, and Mehta et al (2018) reported that *60 to >99% of the object's mass could be lost to ablation. Even so, because comets dissipate energy at high altitude, the blast wave is weaker (Hills and Goda, 1993), which may allow for the survival of organics.…”

Section: Discussionmentioning

confidence: 99%

Cometary Glycolaldehyde as a Source of pre-RNA Molecules

2020

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Over 200 molecules have been detected in multiple extraterrestrial environments, including glycolaldehyde (C 2 (H 2 O) 2 , GLA), a two-carbon sugar precursor that has been detected in regions of the interstellar medium. Its recent in situ detection on the nucleus of comet 67P/Churyumov-Gerasimenko and through remote observations in the comae of others provides tantalizing evidence that it is common on most (if not all) comets. Impact experiments conducted at the Experimental Impact Laboratory at NASA's Johnson Space Center have shown that samples of GLA and GLA mixed with montmorillonite clays can survive impact delivery in the pressure range of 4.5 to 25 GPa. Extrapolated to amounts of GLA observed on individual comets and assuming a monotonic impact rate in the first billion years of Solar System history, these experimental results show that up to 10 23 kg of cometary GLA could have survived impact delivery, with substantial amounts of threose, erythrose, glycolic acid, and ethylene glycol also produced or delivered. Importantly, independent of the profile of the impact flux in the early Solar System, comet delivery of GLA would have provided (and may continue to provide) a reservoir of starting material for the formose reaction (to form ribose) and the Strecker reaction (to form amino acids). Thus, comets may have been important delivery vehicles for starting molecules necessary for life as we know it.

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Caveats to Exogenous Organic Delivery from Ablation, Dilution, and Thermal Degradation

Cited by 18 publications

References 49 publications

Extraterrestrial organic compounds and cyanide in the CM2 carbonaceous chondrites Aguas Zarcas and Murchison

Extraterrestrial organic compounds and cyanide in the CM2 carbonaceous chondrites Aguas Zarcas and Murchison

Exposed Areas Above Sea Level on Earth >3.5 Gyr Ago: Implications for Prebiotic and Primitive Biotic Chemistry

Cometary Glycolaldehyde as a Source of pre-RNA Molecules

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