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| Titel |
Experimental Space Weathering: A coordinated LIBS, TEM, VIS and NIR/MIR study |
| VerfasserIn |
Aleksandra N. Stojic, Sergey Pavlov, Kathrin Markus, Andreas Morlok, Richard Wirth, Iris Weber, Anja Schreiber, Harald Hiesinger, Martin Sohn, Heinz - Wilhelm Huebers |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250133973
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| Publikation (Nr.) |
 EGU/EGU2016-14644.pdf |
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| Zusammenfassung |
| We conducted pulsed infrared laser irradiation experiments, in order to simulate space
weathering triggered modifications of planetary surfaces not protected by an enveloping
atmosphere [1,2], e.g., Mercury. Our work is embedded in the framework of the
BepiColombo space mission to Mercury [3]. The MErcury Radiometer and Thermal
Infrared Spectrometer (MERTIS), an onboard spectrometer will deliver surface
data in the range of 7 – 14 μm once it reaches orbit in 2024 [4]. Space weathering
effects known from other Solar System bodies are likely to be very prominent on
Mercury due to its proximity to the Sun, the lack of a protective atmosphere and
its weak magnetic field [5]. Space weathering effects, e.g., implantation of solar
wind in regolith material, sputtering and (micro) meteorite impacts modify the
planetary surface and thus, therefrom obtained spectral data in the VIS/NIR range
considerably (e.g., reddening and darkening of spectra) [6−9]. We expect modifications
induced by space weathering, known from the VIS/NIR range also to show in the mid
infrared range, probably by amorphisation or similar still unknown effects [2,10].
Our approach is therefore threefold: a) alter analog material artificially by pulsed
laser experiments, b) investigate altered analog material spectrally (VIS/NIR and
MIR range) and c) conduct transmission electron microscopy (TEM) studies on
selected weathered grains to better understand the nanostratigraphy developed by
irradiation and its impact on the resulting infrared spectra. Here, we report on results
obtained from the first set of experiments. Characteristic upper mantle minerals were
taken as analog material, Mg-rich olivine and pyroxene, were ground into a powder
(< 160 μm), slightly compressed into pellets and subsequently irradiated under
high vacuum conditions (∼ 10−6 mbar) with a pulsed (∼ 8ns) infrared laser at a
fluence of ∼ 2 Jcm−2. From the irradiated pellet surfaces, VIS/NIR and MIR spectra
were obtained and selected grains were chosen from which TEM samples were
obtained.
[1] Domingue et al. (2014) Space Sci Rev. 121-214. [2] Pieters (1998) Int Geol Rev.
981–989. [3] Benkhoff et al. (2010) Planet Space Sci. 2–20. [4] Hiesinger et al.
(2010) Planet Space Sci. 144–165. [5] Noble et al. (2003) Sol Syst Res. 31–35. [6]
Yamada et al. (1999) Earth, Planets Sp. 1255–1265. [7] Brucato et al. (2003) Earth,
Moon, and Planets. 307-314. [8] Sasaki et al. (2003) Adv Sp Res. 2537–2542. [9]
Brunetto et al. (2007) Icarus. 381–393. [10] Morlok et al. (2016) Icarus. 352-368. |
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