Valantinas, Adomas (2022). Bright and Dusty Regions of Mars: New Insights from Experiments and Orbital Color Imaging. (Thesis). Universität Bern, Bern
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22valantinas_a.pdf - Thesis Available under License Creative Commons: Attribution (CC-BY 4.0). Download (9MB) | Preview |
Abstract
This thesis investigates active geologic processes and dust composition on Mars using orbital observations and laboratory measurements. The Colour and Stereo Surface Imaging System (CaSSIS) on the ExoMars Trace Gas Orbiter provided new insights into slope streak formation, tropical frost deposits, and the mineralogy of Martian dust. Multi-angular CaSSIS observations revealed that dark slope streaks are rougher and composed of larger particles than surrounding terrains. Some dark streaks were observed to brighten over decadal timescales, suggesting they undergo structural changes rather than rapid dust deposition. Early morning CaSSIS images detected ephemeral frost deposits on high-altitude volcano calderas in the tropics. Thermal modeling indicated these frosts can remain stable for a few hours after sunrise due to the unique thermal conditions atop the volcanoes. Spectral analysis of CaSSIS data from bright, dusty regions indicated ferrihydrite, a hydrated iron oxide, as the dominant iron oxide phase in Martian dust. This suggests cold, icy conditions persisted on Mars for billions of years, preventing crystallization into more stable iron oxides. The presence of amorphous ferrihydrite in dust implies liquid water activity in the last stages of watery Mars. Overall, this work demonstrates the value of CaSSIS observations for studying active surface processes and compositional properties of Mars. The results provide new constraints on recent climate conditions and geologic activity on Mars.
| Item Type: | Thesis |
|---|---|
| Dissertation Type: | Cumulative |
| Date of Defense: | 28 November 2022 |
| Subjects: | 500 Science > 520 Astronomy 500 Science > 530 Physics 600 Technology > 620 Engineering |
| Institute / Center: | 08 Faculty of Science > Physics Institute |
| Depositing User: | Sarah Stalder |
| Date Deposited: | 23 Jul 2024 15:49 |
| Last Modified: | 13 Oct 2024 09:18 |
| URI: | https://boristheses.unibe.ch/id/eprint/5317 |
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