Fault scaling on Mercury – Preparing for ESA’s BepiColombo Mission

Suggested by: Ernst Hauber (Ernst.Hauber@dlr.de), Deutsches Zentrum für Luft- und Raumfahrt (DLR)

Short description: The surfaces of all terrestrial planets (Earth and Moon, Mars, Venus, and Mercury) display evidence for brittle deformation (Fig. 1A: Faulting offsets layers in this rock outcrop; Image: Cornell University), i.e. their crusts and lithospheres have been shear-fractured by faulting [1]. The analysis of fault populations (as part of structural geology) is key to reconstruct the tectonic history of a planet, i.e. the sequence of events that caused tensional and compressional stresses, leading to extensional and contractional faulting, respectively. Contractional faults on Mercury are of particular importance in planetary geology: When Mercury cooled down in its early history, its volume decreased and, correspondingly, its surface area decreased, too, which resulted in the formation of thrust (=contractional) faults [2]. Their quantitative geometric analysis (Fig. 1B: Key geometric parameters of faults; from Fossen (2010)) can, therefore, constrain models of the thermal and interior evolution of Mercury (Fig. 1C: Perspective view of Carnegie Rupes, a prominent contractional fault on Mercury cutting a large impact crater; Image: NASA).  

The BepiColombo mission of ESA (European Space Agency) [3] will arrive at Mercury, the innermost planet in the Solar System, at the end of 2025. Among the onboard instruments, a laser altimeter, BELA (BepiColombo Laser Altimeter [4]; led by the German Aerospace Center, DLR and the University of Bern), will very precisely measure the topography of the surface. To maximize the science return of the mission, and in preparation of BELA’s operations, we will test the performance of BELA and assess the expected improvements in the measurements of fault geometry. In this master thesis, you will measure the fault displacement at several cross-sections along its length (Fig. 1B) and determine the position and amount of the maximum displacement (D_max). You will use existing Digital Elevation Models (DEM, based on stereo images collected by the MESSENGER mission of NASA [5]) and simulated BELA observations and compare your results to previous measurements of D_max. Based on these results, you will predict the expected improvement of thermal evolution models. You will also compare the results (e.g., the relationship of D_max to the fault length, L) to findings for the other terrestrial planets (Fig. 1D shows a comparison between extensional faults on various terrestrial planets). You will work in close contact with the BELA instrument team and will have the opportunity to present your data to international team meeting(s).

References, suggested reading:

1. Watters, T. R. and R. A. Schultz, Planetary Tectonics. Cambridge Uni. Press, Cambridge, 2010.
2. Byrne, P. K. et al., The Tectonic Character of Mercury, in: Solomon, S. C. et al. (Eds) Mercury – The View after MESSENGER, pp. 249-286, Cambridge University Press, Cambridge, 2018.
3. Benkhoff, J., Murakami, G., Baumjohann, W. et al. BepiColombo - Mission Overview and Science Goals. Space Science Reviews, 217, 90, https://doi.org/10.1007/s11214-021-00861-4, 2021.
4. Thomas, N., Hussmann, H., Spohn, T. et al. The BepiColombo Laser Altimeter. Space Science Reviews, 217, 25, https://doi.org/10.1007/s11214-021-00794-y, 2021.
5. Preusker, P. et al., Toward high-resolution global topography of Mercury from MESSENGER orbital stereo imaging: A prototype model for the H6 (Kuiper) quadrangle. Planetary and Space Science, 142, pp. 26-37, https://doi.org/10.1016/j.pss.2017.04.012, 2017.

Links:

• ESA - BepiColombo
• BELA - BepiColombo - Cosmos (esa.int)
• Startseite - DLR Portal
• MESSENGER | NASA

Start: ASAP

Prerequisites/qualification:
You have a working knowledge of remote sensing techniques and are able to work with a GIS system. An interest in geology is not necessary, but would help.