tomkelompa

Tomke Lompa

Museum für Naturkunde Berlin

Doctoral Student

 

Large impact basins are prominent landforms on the Moon and remnants of the late accretion phase when the early Earth-Moon system has formed (time markers). With the use of remote sensing data (LRO mission (topographic data) and GRAIL mission (gravity measurements)) we want to obtain a full inventory of lunar impact basins. We perform numerical simulations to investigate the lunar basin formation process (e.g. modification processes, distribution and mixing of ejected material and impact melt), and use remote sensing data to constrain our models. To consider the state of lunar environment (hot/cold Moon) we include information about the thermal state of the Moon in our simulations. We can show that the pre-impact thermal structure influences the shape of the modeled gravity signature and based on this we can draw conclusions from gravity to the thermal pre-impact target conditions. These findings lead to a much better understanding on how the thermal evolution of the Moon is related to changes on the formation of basins.

yield

Figure1:
Yield strength (dashed lines) as a function of temperature in the target (solid lines). Yield strength in the target material is a parameter thatis sensitive to temperature changes. The figure shows that yield strength of warm material is shifted to lower values compared to material with a colder temperature profile (dashed blue and red lines). Below a depth of approximately 60 km (mantle regime) the differences in yield strength are large. This leads to the assumption that it is mostly the thermally softened behavior of mantle material that influence the crater formation process (mantle exposed at surface (warm target) or crustal cap remains (cold target)).


 
com Model A4

Figure 2:
The upper frame shows the observed (blue) and modeled gravity anomalies for the cold (left) and warm (right) target. Below, the corresponding density structures are shown. The last row presents again the final basin structure for a cold (left) and warm (right) target. Depending on the pre-impact thermal state of the target, the gravity response of the models (blue line) vary (bouguer correction density is 2940 kg/m3).