Simulating Space Weathering in the Transmission Electron Microscope via Dynamic in Situ Heating and Helium Irradiation of OlivineThe chemical composition, microstructure, and optical properties of grains on the surfaces of airless bodies are predominantly altered by micrometeorite impacts and solar wind irradiation. These processes drive space weathering and result in the formation of features including chemically-altered, amorphous grain rims, Fe nanoparticles (npFe), and vesiculated grain textures. These characteristics have been identified in returned samples from the surfaces of the Moon and asteroid Itokawa. In order to advance our understanding of the formation of these microstructural and chemical features in returned samples, we have simulated space weathering processes for a variety of materials via laboratory experiments. These experiments include ion irradiation to simulate solar wind exposure and laser irradiation and in situ heating to simulate micrometeorite impacts. While these experiments have provided considerable insight into the formation mechanisms of many space weathering features, they are predominantly static and typically performed separately. Here we present results from the simulated space weathering of olivine grains via He irradiation and dynamic heating, both performed in situ inside the transmission electron microscope (TEM). These experiments allow for the real-time observation of chemical and microstructural changes resulting from the superposed effects of ion irradiation and pulsed heating.
Document ID
20190002732
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Thompson, M. S. (Purdue Univ. West Lafayette, IN, United States)
Haenecour, P. (Arizona Univ. Tucson, AZ, United States)
Howe, J. Y. (Hitachi High Technologies America Inc. Irving, TX, United States)
(University of Toronto Toronto, Ontario, Canada)
Laczniak, D. L. (Purdue Univ. West Lafayette, IN, United States)
Zega, T. J. (Arizona Univ. Tucson, AZ, United States)
Hu, J. (Argonne National Lab. Lemont, IL, United States)
Chen, W. (Argonne National Lab. Lemont, IL, United States)
Keller, L. P. (ARES Corp. Houston, TX, United States)
Christoffersen, R. (Jacobs Technology, Inc. Houston, TX, United States)