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From Meteorites to OSIRIS-REx

par Caroline CHAMPENOIS - publié le

Mercredi 30 mai- 14h00 - service 252.

Jason P. Dworkin

NASA Goddard Space Flight Center, (Greenbelt,USA).

abstract :
Meteorites : Meteoritic organic compounds trace the history of the solar system ; from quiescent to violent. Species or their precursors were formed in the temperature and radiation extremes of the interstellar medium, the collapse of the protosolar nebula into our solar system, and the environment within fragmented planetessimals before they arrive on Earth to be collected and analyzed. Analyses of primitive carbonaceous chondrites over the last five decades have revealed a major insoluble organic component, as well as a complex and highly diverse suite of soluble organic molecules that includes aliphatic and aromatic hydrocarbons, carboxylic acids, hydroxy acids, N-heterocycles, sugar acids, polyols, amino acids, amines, and many other molecules that have not yet been identified.
Comparing a suite of compounds across meteorite petrology revels correlations with the meteorite parent body, suggesting that thermal and aqueous alteration in primitive asteroids played an important role in the formation and destruction organics, including amplification of L-amino acids that may have contributed to the origin of homochirality in life on Earth. Amino acids are the best studied example [1]. Amino acids are useful, not just because of their obvious relevance to the origin of life and habitability, but the can be employed to elucidate the chemical pathways that were active in a particular meteorite’s parent body [2].

OSIRIS-REx : The OSIRIS-REx mission (Origins, Spectral Interpretation, Resource Identification, and Security Regolith Explorer) is the third NASA New Frontiers mission. It launched September 8, 2016. The primary objective of the mission is to return at least 60 g of “pristine” material from the B-type near-Earth asteroid (101955) Bennu, which is spectrally similar to organic-rich CI or CM meteorites [3, 4]. The study of these samples will advance our understanding of materials available for the origin of life on Earth or elsewhere. The spacecraft will rendezvous with Bennu in 2018 and spend at least a year characterizing the asteroid before executing a maneuver to recover a sam¬ple of regolith in the touch-and-go sample acquisition mechanism (TAGSAM). The TAGSAM head and sample are stowed in the sample return capsule (SRC) and returned to Earth in 2023 for distribution, world-wide analysis, and archiving for future scientists.

References :
[1] Elsila, J.E., et al. (2016) ACS Central Science, 2, 370-379.
[2] Aponte, J.C., et al., (2017) ACS Earth and Space Chemistry, 1, 3-13.
[3] Lauretta D. S. et al. (2017) Space Sci. Rev. 212, 925–984.
[4] Clark et al. (2011) Icarus 216, 462-475.

Contact : Grégoire Danger et Alexander Ruf


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