The evolution of the early solar system

14-236-LunarGrailMission-OceanusProcellarum-Rifts-Overall-20141001_800wThe Department of Earth Science and Engineering at Imperial College has found that sampling the dark, basaltic plains of our Moon may reveal the organic matter present in our early solar system.

Between 4.2 and 3.7 billion years ago, the inner solar system underwent an intense bombardment of asteroids. Previous analysis of meteorites indicates that this bombardment both generated organic compounds and delivered them to planetary surfaces. Some of these compounds, such as amino acids, nucleo-bases and carboxylic acids are the building blocks of life.

Records of Earth’s organic chemistry before 3.8 billion years ago has been completely obliterated by violent volcanic activity and movement of tectonic plates, which generated so much heat and pressure that all of Earth’s oldest rocks have been severely altered. These alterations make it impossible to interpret the ancient terrestrial environment using material from Earth.

Moon_names.svgIn order to understand the conditions that gave rise to the life-generating capacity of Earth, we require a record of the materials that were circulating and impacting Earth during the early phases of land, ocean and atmosphere formation. During this early period, the moon would have been subject to the same delivery of organic compounds as Earth. Thus an archive of organic material could remain buried in the loose, heterogeneous dust and rock covering the moon, intercalated with larva flows from the early lunar volcanoes.

This study, published in Astrobiology, simulated the lunar environment 3.8 billion years ago. A synthetic material that resembles rocky dust from the moon (modelled on lunar samples such as those brought back by Apollo 11) was studied in response to the effects of heating by overlying lava flows. The experiment demonstrated that early lunar conditions appeared to promote polymerisation of organic molecules, thus allowing them to be stable enough to persist on the moon for us to study them, billions of years later.

These findings reveal the lunar conditions that would have allowed the preservation of early organic molecules in the solar system. Analysing material from the moon will therefore facilitate understanding of the early conditions present in our solar system

Charlotte Mykura is a second year PhD student studying epigenetics

Images: Oceanus Procellarum (The Ocean of Storms),  a broad region covered in dark mare basalt; The major maria and craters of the Moon (Wikimedia Commons)

Citation: Matthewman, R. et al. (2015) The Moon as a Recorder of Organic Evolution in the Early Solar System: A Lunar Regolith Analog Study. Astrobiology, 15(2): 154-168. doi:10.1089/ast.2014.1217.

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