Organic Matter in Cometary Environments

McKay, Adam; Roth, Nathan X.

doi:10.3390/life11010037

Cited by 12 publications

(3 citation statements)

References 155 publications

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“…Instead, they may come from the initial endowment (presumed to be analogous to comets or carbonaceous chondrites), or from thermogenesis of complex organic materials (McKay et al 2012;Peter et al 2023). All of the three abovementioned species have been found in comets and carbonaceous chondrites (Breger et al 1972;Pizzarello 2012;McKay & Roth 2021). After the exogenic delivery of these organics, they would be subject to hydrolytic degradation, with a reaction half-life time of HCN that was estimated to be less than 10 5 yr at 0°C (Stribling & Miller 1987;Miyakawa et al 2002;Glein et al 2008).…”

Section: The Sources Of Thermodynamically Unfavorable But Possibly De...mentioning

confidence: 99%

The Potential for Organic Synthesis in the Ocean of Enceladus

Liu,

Xu,

Zhang

et al. 2024

ApJ

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The Cassini spacecraft detected a soup of organics in the plume of Saturn’s moon Enceladus. Those compounds could provide building blocks for the potential emergence or sustenance of microbial life in Enceladus’ subsurface ocean. However, the sources and stabilities of organics in Enceladus’ ocean are still poorly understood. Here, we perform nonequilibrium thermodynamic calculations to assess the energetics of abiotic synthesis for a broad spectrum of small organic molecules under both cold oceanic and hydrothermal conditions on Enceladus. Most of the organics that we studied are thermodynamically favorable to synthesize at micromolal dissolved concentrations over wide ranges of pH (8.5–11) and redox conditions. This suggests that many of the organic compounds detected by Cassini may be derived from reactions of CO2 and H2. However, some widely assumed precursors of biomolecules, such as formaldehyde, hydrogen cyanide, and acetylene, are found to be unstable and therefore unfavorable to be synthesized. We found that higher temperatures also seem to favor the synthesis of organic species under Enceladus hydrothermal conditions. Detection of thermodynamically unstable species in the plume might reflect artifacts introduced during high-speed spacecraft flybys and/or active synthesis via degradation of primordial chondritic organics, or biological activities.

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Section: The Sources Of Thermodynamically Unfavorable But Possibly De...mentioning

confidence: 99%

The Potential for Organic Synthesis in the Ocean of Enceladus

Liu,

Xu,

Zhang

et al. 2024

ApJ

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“…Comets contain a number of nitrogen-containing species, including HCN, HNC, HNCO, CH 3 CN, HC 3 N, and NH 2 CHO [ 56 , 57 ]. Furthermore, N 2 has been detected for the first time in situ in comet 67P/Churyumov–Gerasimenko by ROSINA/Rosetta [ 58 ].…”

Section: Nitrogenmentioning

confidence: 99%

Sources of Nitrogen-, Sulfur-, and Phosphorus-Containing Feedstocks for Prebiotic Chemistry in the Planetary Environment

Todd

2022

Life

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Biochemistry on Earth makes use of the key elements carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur (or CHONPS). Chemically accessible molecules containing these key elements would presumably have been necessary for prebiotic chemistry and the origins of life on Earth. For example, feedstock molecules including fixed nitrogen (e.g., ammonia, nitrite, nitrate), accessible forms of phosphorus (e.g., phosphate, phosphite, etc.), and sources of sulfur (e.g., sulfide, sulfite) may have been necessary for the origins of life, given the biochemistry seen in Earth life today. This review describes potential sources of nitrogen-, sulfur-, and phosphorus-containing molecules in the context of planetary environments. For the early Earth, such considerations may be able to aid in the understanding of our own origins. Additionally, as we learn more about potential environments on other planets (for example, with upcoming next-generation telescope observations or new missions to explore other bodies in our Solar System), evaluating potential sources for elements necessary for life (as we know it) can help constrain the potential habitability of these worlds.

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“…Here, we have hypothesized an environment relatively rich in H, CN, CO and unsaturated organic substrates as observed in patches on 67P/Churyumov-Gerasimenko and other comets. [47][48][49] In the 2 nd reaction step, H addition, one propene molecule must be replaced by an atomic H resulting in a 1e À change. The total reaction is energetically favored by DG = À39.6 kcal mol À1 with a barrierless addition of H to the Ni center (see ESI †).…”

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confidence: 99%