Abstract DGP2026-86

When planetary surfaces interact with volatiles – a spectral and mineralogical study

T. Michalik (1), C. Hamann (1), A. Maturilli (2)

(1) Museum für Naturkunde Berlin, Invalidenstr. 43, 10115 Berlin, Germany (2) Deutsches Zentrum für Luft- und Raumfahrt e.V., Rutherfordstr. 2, 12489 Berlin, Germany

Reflectance spectroscopy is one of the most important tools to characterize planetary surfaces remotely. In this study, we investigate how interaction with volatiles under the influence of heat can alter spectral properties of differentiated planetary surface materials.

Many solar system objects are rich in volatile-bearing species, like for example carbonaceous chondrites or C-type asteroids. Thus, when impact events produce heat, mineralogical/chemical changes might be occurring due to the release of (previously bound) volatiles.

We present reflectance spectra in ultra-violet, visible and near-infrared wavelengths of unheated and heated plagioclase, hypersthene and the carbonaceous chondrite slabs as well as granular mixtures of those three. We heated these materials to 600 °C for two weeks in air and in vacuum.

All heated materials that were heated in presence of either air or carbonaceous materials show a significant increase in reflectance in the UV, VIS and NIR wavelength ranges. While this research is still ongoing, we found that very small crystals formed on the surface of the plagioclase surfaces. Upcoming analysis include microprobe analysis and transmission electron microscopy in order to understand the induced spectral changes on a mineralogy level.

Local features with elevated albedos occur on various bodies like planets, asteroids and moons. In many cases, they provoke the interest of scientists due to their unknown origin. On Mercury for example, the so-called ‘hollows’ show higher reflectances than their surroundings [1]; as do the lunar swirls on the moon [2] and some pitted impact deposits [3] as well as the so-called ‘orange material’ [4] on the asteroid Vesta.

Many studies focus on the effects of shock during an impact event. Yet shock commonly causes the darkening of a spectrum and weakening of absorption bands. With heat, it appears to be the other way round as reflectance can increase significantly. We certainly need more insight into the combined effects during an impact and on the material’s reflectance patterns.

References

[1] Blewett et al. (2011) Science 333, p. 1856. 10.1126/science.1211681

[2] Kramer et al. (2011) JGR 119, E00G18. 10.1029/2010JE003729

[3] Michalik et al. (2021) Icarus 369, 114633. 10.1016/j.icarus.2021.114633

[4] Le Corre et al. (2013) Icarus 226, p. 1568. 10.1016/j.icarus.2013.08.013