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.