An Experimental Investigation of Space Weathering Processes of Regoliths on Primitive Carbonaceous Asteroids

Changes in surface composition, microstructure, and optical reflectance in the near-surface region of the Murchison meteorite after solar-wind type ion irradiation


Project 4 - Image 1 .png

Solar-wind type radiation processing using laboratory H and He ion irradiation and characterization of irradiation effects by X-ray photoelectron spectroscopy (Task 1 relevance) Task 1 Summary and Objectives. This task will focus on ion irradiation of the Murchison CM2 carbonaceous chondrite using both 1 keV H+ and 4 keV He+ ions with a range of total fluences, from 1015 to 1018 ions/cm2, simulating relevant energies and exposure timescales for solar wind effects on airless bodies. We will determine the detailed changes in surface morphology, chemical composition, and microstructure of the samples in response to ion irradiation using surface analysis and electron beam techniques. We will correlate these changes with features in laboratory reflectance spectra over UV-IR wavelengths. Background. The effects of solar wind irradiation on carbonaceous materials will be investigated by irradiation experiments on chips of the Murchison CM2 carbonaceous chondrite. Murchison was selected because its spectral reflectance characteristics are similar to the spectral data from asteroid Bennu. Preliminary proof-of-concept results on a chip of Murchison irradiated with 4 keV He+ to a total fluence of 1018 cm-2 indicate amorphization and vesiculation of matrix phyllosilicates and a loss of OH inferred by a reduction in the band depth of the 3 µm OH/H2O feature observed with Fourier-transform infrared spectroscopy (FTIR) analyses. We observed that the irradiated matrix phyllosilicates underwent oxidative reduction with an increase in Fe2+/Fe3+ from loss of O through preferential sputtering, however, we did not observe the production of npFe0 grains in response to irradiation. UVa Project Plan. We will build on this previous work by fully characterizing samples of Murchison by X-ray photoelectron spectroscopy (XPS) before and after irradiation by 1 keV/amu H+ and He+ ions to various fluences. We may also investigate changes in spectral properties across Visible-NIR wavelengths using in situ reflectance (UVa) or ex situ diffuse reflectance (JSC or Univ. Winnipeg), and correlate these findings to alterations in the chemical and microstructural characteristics of the samples observed by TEM (measurement taken by PI and JSC team). This work will provide a comprehensive and thorough analysis of the response of carbonaceous materials to solar wind ion irradiation.

PI: M. Thompson (Purdue University)

Co-I/UVa PI: C.A. Dukes (Research Scientist)

UVa Contributors: C. A. Dukes

Publications and Proceedings:

D. Laczniak, Thompson, M., Christoffersen, R., Dukes, C., Clemett, S., Morris, R., & Keller, L., Investigating Space Weathering Effects on Carbonaceous Asteroids Using High-flux and Low-flux Ion Irradiation of the Murchison Meteorite, Microscopy & Microanalysis, 27(S1), 2538-2541, (2021) doi:10.1017/S143192762100903X

D. Laczniak, Thompson, M., Christoffersen, R., Dukes, C. A., Clemett, S., Morris, R., & Keller, L., Characterizing spectral, microstructural, and chemical effects of solar- wind irradiation on carbon-rich asteroids: Coordinated analysis of H+ and He+-irradiated Murchison carbonaceous chondrite, Icarus 364, 114479, (2021) https://doi.org/10.1016/j.icarus.2021.114479

Laczniak, D., Thompson, M., Dukes, C., Morris, R., Clemett, S., Keller, L., & Christoffersen, R., Investigating Space Weathering Effects Using Coordinated Analysis of a H - and He -Irradiated Carbonaceous Chondrite, Microscopy and Microanalysis, 26(S2), 2598-2601 (2020) doi:10.1017/S143192762002214X

D. L. Laczniak, M. S. Thompson, R. Christoffersen, C.A. Dukes, R. V. Morris, and L. P. Keller, Understanding the role of ion flux in solar wind space weathering: low flux H+ and He+ irradiation of the Murchison meteorite, 53rd LPSC Abstract# XXXX (2022)

Thompson, M. S., Laczniak, D. L., Morris, R. V., Clemett, S. J., Loeffler, M. J., Dukes, C. A., Trang, D., Keller, L. P., and Christoffersen, R., Understanding the Space Weathering of Returned Samples through Coordinated Analysis. Royal Astronomical Society Meeting Conference on the Analysis of Returned Extraterrestrial Samples (2021)

Glotch T. D., Thompson M. S., Dukes C. A., Loeffler M. J., Micro-FTIR Imaging and Spectroscopy of Experimentally Space-Weathered CM Chondrite Murchison, 52nd LPSC Abst# 1458 (2021)

D. L. Laczniak, M. S. Thompson, R. Christoffersen, C. A. Dukes, S. J. Clemett, R. V. Morris, and L. P. Keller, Understanding Space Weathering of Carbonaceous Asteroids through H+ and He+ Ion Irradiation of the Murchison Meteorite, 52nd LPSC Abst# 2361 (2021)

M.S. Thompson, D.L. Laczniak, M.J. Loeffler, C.A. Dukes, S.J. Clemett, R.V. Morris, T.D. Glotch, R. Christoffersen, L.P. Keller, Understanding the Space Weathering of Returned Samples through Coordinated Analysis, Goldschmidt2021 • Lyon, France • 4 - 9 July (2021)

D.L. Laczniak, M. S. Thompson, R. Christoffersen, C.A. Dukes, S. J. Clemett, R.V. Morris, and L.P. Keller, Investigating Space Weathering Effects on Carbonaceous Asteroids Using High-flux and Low-flux Ion Irradiation of the Murchison Meteorite, Microscopy & Microanalysis 2021• Pittsburgh, PA (2021)

D. L. Laczniak, M. S. Thompson, C. A. Dukes, R. V. Morris, S. J. Clemett, L.P. Keller, and  R. Christoffersen, Preparing for C-complex asteroid sample return: Investigating space weathering effects using coordinated analysis of a He+ and H+ irradiated carbonaceous chondrite, 51st LPSC, Abst#2667 (2020)

M.S. Thompson, D.L. Laczniak, R.V. Morris, S.J. Clemett, M.J. Loeffler, C.A. Dukes, D. Trang, L.P. Keller, R. Christoffersen and D.G. Agresti, The Effects of Space Weathering on the Orginaic and Inorganic Compounds of a Carbonaceous Chondrite: Implications for Returned Samples from Hayabusa2 and Osiris-Rex, Asteroid Science in the Age of OSIRIS-REx and Hayabusa2, Nov., Tucson, AZ (2019)

Laczniak, D. L., Thompson, M. S., Dukes, C. A., Morris, R. V., Clemett, S. J., Keller, L. P., & Christoffersen, R., Coordinated Analysis of an Ion Irradiated Carbonaceous Chondrite, 82nd Annual Meeting of The Meteoritical Society, 7-12 July, 2019 in Sapporo, Japan. LPI Contribution No. 2157, id.6434 (2019)

Laczniak, D. L.; Thompson, M. S.; Dukes, C. A.; Morris, R. V.; Clemett, S. J.; Keller, L. P.; Christoffersen, R., Coordinated Analysis of an Ion Irradiated Carbonaceous Chondrite Suggests Complex Space Weathering Effects, 50th Lunar and Planetary Science Conference, 18-22 March at The Woodlands, Texas. LPI Contribution No. 2132, id.1972 (2019)