Organic material in meteorites and the link to the origin of life

Abstract

Abstract. Life requires specific conditions that have been, so far, only proven to meet on Earth. Though the chemical elements required to form living organism (C, H, N, O, S, etc) are widespread in the universe, the molecules that are crucial for Life, like nucleobases or amino acids, may not be so ubiquitous. The question of the formation of small and complex molecules is highly relevant to understand the process of Life origin. Carbonaceous chondrites are a class of meteorites rich in organic compounds and host potential precursors for the emergence of Life (organic matter and water). They could have been the source of complex molecules on the early Earth. This contribution will describe the main properties of the organic matter recovered from carbonaceous chondrites. However, the isotopic and molecular record of organic compounds is faded by secondary processes that occurred on the parent body of these meteorites. This results in complex signatures that raise multiple questions about the origin of organic compounds in the Solar System.

Macromolecular organic compounds from the depths of Enceladus

“…% insoluble organic carbon 58 . This insoluble organic matter (IOM) 59,60,61,62,63 is considered partly of primordial origin, i.e. inherited from the interstellar medium, and partly modified due to early hydrothermal processing on carbonaceous chondrite parent bodies.…”

“…It is macromolecular, and most of the carbon is incorporated in small aromatic structures, with about 20 to 30 % of the carbon constituting aliphatic bonds. The maximum length is 7 carbon atoms for aliphatic bridges between aromatic units, and 4 carbon atoms for the side chains with a free end 60,61 . Functional groups containing O, N, and S are also abundant (see figure 2 in Remusat, 2014 61 ).…”

Thermal metamorphic history of Antarctic CV3 and CO3 chondrites inferred from the first- and second-order Raman peaks of polyaromatic organic carbon

“…Some chondrites, especially carbonaceous chondrites, contain up to 4 wt.% organic carbon in the form of soluble and insoluble organic matter, the latter comprising about ~80% of the total organic carbon (Remusat, 2014). Secondary processes such as thermal metamorphism, aqueous alteration, brecciation, and impact shock can modify the organic content of chondrites (Botta and This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.…”

Zhamanshin astrobleme provides evidence for carbonaceous chondrite and post-impact exchange between ejecta and Earth’s atmosphere

“…Large-scale planetary collisions and smaller impacts are important processes that may add to the chemical makeup of the bodies in the Solar System and shape the planetary surfaces by forming variably sized craters, layers of impact ejecta, and shock deformation features. Some meteorites, in particular carbonaceous chondrites, contain high concentrations of organic matter and volatiles like water, and are considered to potentially bear on the emergence of oceans and life 1 . The identification of projectile types for impacts is thus central for tracing the origin and aftermath of collisions.…”