Constrained Lunar Density Inversions

Constrained Lunar Density Inversions

Heijkoop, E.

van der Wal, W. (mentor)

Aerospace Engineering

Space Engineering

Astrodynamics & Space Missions

2017-06-02

This thesis presents the results of a developed density inversion tool, which estimates lunar crustal density anomalies from Bouguer anomalies. The tool is run through a number of tests for verification, culminating in the forward modeling and subsequent inversion of synthetic density anomalies, showing a > 97% recovery of the original density anomalies. The density inversion is applied to a number of lunar regions. The region containing the landing sites of the Apollo 12 & 14 missions is selected first. The results of this region are consistent with returned samples, providing validation of the inversion. Next, Mare Crisium and Mare Orientale are selected, to give insight into the formation of melt sheets after impacts and subsequent mantle upwelling to achieve isostatic equilibrium. To do this, the tool was expanded to estimate multiple layers of density anomalies, which required constraining with the help of a priori information, which itself was in part derived from lunar seismology. Such constraining is necessary to remove the non-uniqueness inherent in inversion. The results show that Mare Crisium still contains a thin sheet of several (4 to 6) km thickness on the crater floor, showing that mantle upwelling has not reached the surface. For Mare Orientale a melt sheet of higher density than the surrounding crust (2650 kg m−3 vs 2550 kg m−3 ) is found with a thickness consistent with Zuber et al. [2016] (10 km). If this higher density is not present, the melt sheet is thinner than that proposed by Zuber et al. [2016] (6 km vs 8 km), thus showing a slight mismatch in consistency between normal and raised density for the melt sheet.

Gravimetry
Inversion
Moon
Planetary Science

http://resolver.tudelft.nl/uuid:0c0e4624-7c4c-4eb5-8f0a-2334089d56e2

Student theses

master thesis

(c) 2017 Heijkoop, E.