Lunar magnetism: field evolution and dynamo generation – MagLune

We will perform unprecedented magnetic measurements on the main masses (50 g to 5 kg) of 200 Apollo samples directly in their storage room, as well as on lunar meteorites, from which we will then select a few key samples for detailed paleomagnetism and thermochronology study in the laboratory. This will provide well-dated tie points in the evolution of the strength of the lunar surface paleofield.
From the inversion of magnetic field orbital data we will determine the crustal magnetizations associated to lunar magnetic anomalies. This will constrain the geometry and intensity of the ancient lunar field. Inversions for the depths of magnetization will be used to determine if the magnetic sources lie in near-surface impact ejecta deposits, magmatic intrusions, or deeper in the crust.
These data will constrain the history of the lunar dynamo and will provide crucial constraints on dynamo models that are powered by either thermo-solutal dynamos (mantle overturn or core crystallization) or mechanical forcings such as impacts or precession. We will perform numerical simulations that couple the thermal evolution of the Moon and dynamo generation, test these different scenarios and compare the predicted field evolution to paleomagnetic data.

project in progress

project in progress

project in progress

Beyond the Earth, the Moon is the only planetary body for which we have data constraining our understanding of planetary magnetic field evolution over a long timescale. However, rather than confirming the generic validity of the models developed for the Earth, the Moon challenges our current understanding. For instance, paleomagnetic measurements by our consortium show that the Moon had a dynamo field between at least 4.2 and 3.6 Ga, with surface strengths greater than 10 µT, which is ten times larger than the predictions of our best lunar dynamo models. The origin of lunar magnetic anomalies, and how the strength of a putative dynamo field varied with time are also keys to understanding deep structure of the Moon and its thermal evolution. In this project, we will set-up a first-of-its-kind collaboration between complementary research groups to encompass all aspects of lunar magnetism: paleomagnetism and magnetic properties of lunar samples, modeling of orbital magnetic field data, and dynamo modeling.
We will perform unprecedented magnetic measurements on the main masses (50 g to 5 kg) of 200 Apollo samples directly in their storage room, as well as on lunar meteorites, from which we will then select a few key samples for detailed paleomagnetism and thermochronology study in the laboratory. This will provide well-dated tie points in the evolution of the strength of the lunar surface paleofield.
From the inversion of magnetic field orbital data we will determine the crustal magnetizations associated to lunar magnetic anomalies. This will constrain the geometry and intensity of the ancient lunar field. Inversions for the depths of magnetization will be used to determine if the magnetic sources lie in near-surface impact ejecta deposits, magmatic intrusions, or deeper in the crust.
These data will constrain the history of the lunar dynamo and will provide crucial constraints on dynamo models that are powered by either thermo-solutal dynamos (mantle overturn or core crystallization) or mechanical forcings such as impacts or precession. We will perform numerical simulations that couple the thermal evolution of the Moon and dynamo generation, test these different scenarios and compare the predicted field evolution to paleomagnetic data.