Atmospheric entry heating of micrometeorites at Earth and Mars: implications for the survival of organics

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Title: Atmospheric entry heating of micrometeorites at Earth and Mars: implications for the survival of organics
Authors: Wilson, A
Genge, M
Krzesińska, A
Tomkins, A
Item Type: Journal Article
Abstract: The atmospheric entry heating of micrometeorites (MMs) can significantly alter their pre-existing mineralogy, texture and organic material. The degree of heating depends predominantly on the gravity and atmospheric density of the planet on which they fall. For particles falling on Earth the alteration can be significant, leading to the destruction of much of the pre-entry organics, however, the weaker gravity and thinner atmosphere of Mars enhances the survival of MMs and increases the fraction of particles that preserve organic material. This paper investigates the entry heating of MMs on the Earth and Mars in order to examine the micrometeorite population on each planet and give insights into the survival of extraterrestrial organic material. The results show that particles reaching the surface of Mars experience a lower peak temperature compared to Earth and, therefore, experience less evaporative mass loss. Of the particles which reach the surface, 68.2% remain unmelted on Mars compared to only 22.8% on Earth. Due to evaporative mass loss, unmelted particles that reach the surface of Earth are restricted to sizes <70 µm whereas particles >475 µm survive unmelted on Mars. Approximately 10% of particles experience temperatures below ~800 K, i.e. the sublimation temperature of refractory organics found in MMs. On Earth this fraction is significantly lower with less than 1% expected to remain below this temperature. Lower peak temperatures coupled with the larger sizes of particles surviving without significant heating on Mars suggests a much higher fraction of organic material surviving to the martian surface.
Issue Date: Sep-2019
Date of Acceptance: 7-Jun-2019
DOI: 10.1111/maps.13360
ISSN: 1086-9379
Publisher: Wiley
Start Page: 1
End Page: 19
Journal / Book Title: Meteoritics and Planetary Science
Volume: 54
Issue: 9
Copyright Statement: © The Meteoritical Society, 2019. This is the accepted version of the following article: Wilson, A. P., Genge, M. J., Krzesińska, A. M. and Tomkins, A. G. (2019), Atmospheric entry heating of micrometeorites at Earth and Mars: Implications for the survival of organics. Meteorit Planet Sci, 54: 1-19, which has been published in final form at
Sponsor/Funder: Science and Technology Facilities Council (STFC)
Science and Technology Facilities Council (STFC)
Funder's Grant Number: ST/M003167/1
Keywords: Science & Technology
Physical Sciences
Geochemistry & Geophysics
0201 Astronomical and Space Sciences
0402 Geochemistry
0403 Geology
Geochemistry & Geophysics
Publication Status: Published
Embargo Date: 2020-07-15
Online Publication Date: 2019-07-15
Appears in Collections:Faculty of Engineering
Earth Science and Engineering

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