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This article discusses the formation of organic molecules in interstellar and circumstellar environments and their transport, or not, to protostellar disks.
We consider the chemistry occurring in protoplanetary disks and its possible contribution to the organic inventory of primitive solar system bodies. First, we outline the main physical and chemical processes associated with the formation of solar-type stars and their accretion disks. We then summarise the current observational status of protoplanetary disks and review chemical models of them. Finally,...
The present census of the galactic planetary population shows that planets exist outside the Solar System. But the empirical evidence is still insufficientt estimate the overall preconditions for the diversity and abundance of habitats that planets may provide in our galaxy. Detecting planets is still centered around giant planets in orbits with periods comparable and less than Jupiter’s around nearby...
Elemental carbon is formed in stars at the end of their life cycle and is ejected in the interstellar medium. Through a review of the elemental forms of carbon, it is possible to have a clearer picture of the formation and the evolution of this element in space, its ability to build complex molecular and macromolecular species, and its basis for the subsequent formation, under prebiotic conditions,...
In the Solar System three types of atmospheric environments can be found: the highly oxidized Earth-like atmospheres, the mildy reduced atmospheres of Titan, Pluto and Triton, and the highly reduced atmospheres of the giant planets. In the terrestrial atmospheres carbon, the most abundant element in the Universe after hydrogen, helium and oxygen, is mostly combined with oxygen to form carbon dioxide...
Interpretations of telescopic observations show that H2O ice is ubiquitous on surfaces throughout many regions of the outer Solar System. Additionally, carbon-bearing molecular material is emerging as a major component in the outer Solar System, where it appears entrained in H2O ice on comets and many planetary satellites, and in the more volatile N2 ice on Triton and Pluto. Complex macromolecular...
By delivering prebiotic molecules to the Earth, comets could have played a role in the early phases of the development of life on our planet. In order to explore this possibility, we present here an assessment of the molecular content of comets. The current methods of investigations — by both in situ analysis and remote sensing — are reviewed. The present status of our knowledge of the composition...
The recent discovery of a large number of Solar System bodies that orbit the Sun beyond Neptune has opened new possibilities to study primordial matter and processes in the early solar nebula. Indeed, Kuiper Belt objects are the most primitive solid bodies in the solar system. Due to their intrinsic faintness and remoteness, these objects are very diffcult to study, and progress is slow. I will review...
Interplanetary Dust Particles are amongst the most pristine materials of the Solar System that can be studied here on Earth. The study of these primitive particles gives a lot of information about the evolution of our Solar system and about the delivery of (pre-)biotic material on Earth. Although the sample size of IDPs is small, typically 10−9 gram, this does not prevent the study of them and several...
Because of the paucity of geologic samples dating back to the early Earth, trying to unveil the nature of the prebiotic terrestrial environment is as frustrating as it is fascinating. An understanding of the characteristics of this period in our planet’s history is, however, crucial to studies of the origin of Life. Recent progress in astrophysics, geochemistry and simulation of planetary accretion...
The evidence for early life and its initial evolution on Earth is linked intimately with the geological evolution of the early Earth. The environment of the early Earth would be considered extreme by modern standards: hot (50–80°C), volcanically and hydrothermally active, anoxic, high UV flux, and a high flux of extraterrestrial impacts. Habitats for life were more limited until continent-building...
On earth, organic matter of biological origin is subjected to various alteration processes, dominated by oxidation and thermal metamorphism due to deep burial, typically a result of plate-tectonic processes. Other alteration processes unrelated to the oxidizing atmosphere and plate tectonics include impact metamorphism, irradiation and thermal degradation of dissolved organic species. The implications...
The macromolecular carbonaceous material contained in the meteorites of Orgueil, Murchison and Tagish Lake, and in an early Archean chert from the Warrawoona Group (Australia) was analyzed by Electron Paramagnetic Resonance. The meteoritic macromolecular material distinguishes itself from its terrestrial counterpart by the presence of diradicaloids (alkyl polysubstituted aromatic moieties bearing...
Astrobiology is an emerging interdisciplinary science that investigates experimentally the origin of life on the Earth and its distribution in the Universe. It encompasses scientific disciplines from astronomy to geology, chemistry, paleontology, biology and ecology with the goal to understand — to name only a few examples — the formation of solar systems (through detection of extrasolar planetary...
We discuss the role of formamide, a product of hydrolysis of hydrogen cyanide (HCN), as precursor of relevant components of nucleic acids in prebiotic conditions and describe the efficient synthesis of purine, adenine, cytosine, thymine, and 5-hydroxymethyluracil. The remarkable formation of some purine acyclonucleosides is also reported, providing a possible solution to the problem of the elusive...
The two other solar system bodies thought to be most compatible with “life as we know it” are the planet Mars and Europa, a natural satellite of the planet Jupiter. These worlds appear to harbor the potential for past and/or present-day liquid water, biologically useful energy sources, and a significant and rich organic chemistry. Such traits are under active investigation both through ongoing, targeted,...
The first part of this chapter contains a brief history of some of the key events leading to initiation of NASA’s Astrobiology program in the late 1990s. The perspective taken is than of a non-specialist and emphasis is placed on policy issues rather than key scientific discoveries. A basic conclusion that can be drawn from the circumstances surrounding the initiation of the program is that a combination...
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