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Micrometeoritic Contribution of Volatile Organics to Earth-Like Atmospheres

By Alice Pevyhouse


Earth accretes 30 million kg/yr of extraterrestrial material, mostly in the form of large micrometeorites (diameter ~ 200 µm). Entry velocities of these particles range from 11.2 km/s to 70 km/s. Micrometeorites are small enough to ensure that they are completely melted and partially evaporated during atmospheric entry. Such strong heating has typically been inferred to cause complete destruction of the organic content of the particles in this size range. Earlier work by Kress et al. (2002) showed that volatile organics, including CH4 and small-functionalized polycyclic aromatics, are evolved from flash-heated micrometeorite-analogs. Contribution of ablated organics to atmospheric chemistry depends in part on the rate of compound degradation due to solar Lyman-alpha (lambda = 121.5 nm). The rate of degradation is a function of the total amount of planetary atmosphere an organic compound is released under. Results show volatile organics are released between 86 - 122 km for particles entering at an 80 deg angle of entry and initial velocity of 12 km/s. Exposure to UV radiation at this altitude range will degrade released organics before they are vertically mixed deeper

Topics: Physics; Astronomy and Astrophysics
Publisher: SJSU ScholarWorks
Year: 2010
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