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.

 

Impact Crater Geometry 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: Any planetary surface is subject to impact cratering [1], and impact craters are the dominating landform on many objects in the Solar System that have a solid surface [2]. The sizes and shapes of the resulting impact craters (Fig. 1A shows part of Mercury’s surface with different impact crater morphologies) depend on several factors such as the speed and mass of the incoming bolides, and the mechanical properties of the target substrate. For example, as a rule of thumb a larger impactor will create a bigger crater. The size and cross-sectional shape of the crater will also depend on the target material (e.g., sand or solid rock) and its stratigraphy (e.g., whether the target material is layered or not). The analysis of impact crater geometry can therefore yield insights about the nature of the crater-forming impact and the geology of the planetary surface. 

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 LaserAltimeter [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 accumulate a database of craters on Mercury based on the best currently available data sets. In this master thesis, you will measure the cross-sectional geometry (Fig. 1B shows several key morphometric parameters) of impact craters on Digital Elevation Models (DEM) based on stereo images collected by the MESSENGER mission of NASA [5]. For each crater, you will automatically determine 180 individual topographic profiles (in a 1° azimuthal spacing) through the crater center, applying existing GIS software that was specifically designed for this task. Together with the profile and the geographic location of the crater center, you will also record additional (meta)data such as the degradation state of the crater and the geologic unit in which it is located. You will also compare the results (e.g., the depth to diameter relationship of the craters) to findings on the other terrestrial planets (Fig. 1C shows a comparison to the other 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. Melosh, H.J., Impact Cratering – A Geologic Process. Oxford Univ Press. New York, 1989.
2. Osinski, G. R. and E. Pierazzo, Impact Cratering – Processes and Products. Wiley-Blackwell, Chichester, 2013.
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.

Morphometry of Irregularly Shaped Small Planetary Bodies: Comparison and Evaluation of Mapping Tools for Asteroids and Comets

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

Short description: Recent space missions to small planetary bodies, such as asteroids and comets, have discovered a wealth of morphology. Due to their small size, the shape and morphology of their surface features, including amongst others craters, boulders, dust, and linear features, are divers and complexly connected to the physical environment they form in (e.g. low gravitational pull, environment of space surrounding it, extreme local temperature variations). Thus, the surface features offer the opportunity to learn more about the environment present on small planetary bodies. To understand the effect that the environment has on the formation and evolution of the various surface features on different planetary bodies, it is necessary to precisely measure their size, distribution, orientation, and other physical parameters. However, this is challenging given the complexly shaped, irregular bodies and a variety of different tools to map small planetary bodies.

This master thesis will apply commonly used tools (e.g. QGIS, Small Body Mapping Tool, Meshalb) to measure morphologic parameters of surface features on small bodies. The aim is to access the applicability of these tools, conduct sample measurements and compare measurements of the same body using different tools. Ultimately, a judgement on the different tools’ reliability and applicability is desired.

References/Suggested reading:

• Murdoch N, Sanchez P, Schwartz SR, Miyamoto H. Asteroid Surface Geophysics. In: Michel P, DeMeo F, Bottke WF, editors. Asteroids IV. Tucson, Arizona, USA: University of Arizona Press; 2015
• https://sbmt.jhuapl.edu/

Start: Autumn 2023

Prerequisites/qualification:

• Experience with mapping tools would be useful
• Interest in asteroids, comets and space missions