Deciphering the magnetic record of planetary rocks using spacecraft and laboratory measurements - PETRA
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 844252.
The research has been carried out at the Paleomagnetism Laboratory of Massachusetts Institute of Technology (MIT, USA), under the supervision of Prof. Benjamin P. Weiss, at the Paleomagnetism Research Group of Institut de Physique du Globe de Paris (IPGP, France), under the supervision of Dr. France Lagroix, and in collaboration with Dr. Vincent Lesur, member of the Geomagnetism Research Group of Institut de Physique du Globe de Paris (IPGP, France).
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“Petra” means “rock” in greek. This word often reminds me of a relative who asked me once in a condescending (towards rocks) manner: “What do you have to do with rocks? You are an electrical engineer.” Well, I am fascinated by rocks, as I am fascinated by Nature in general. The slightest thing brims with beauty and is characterized by a level of complexity that leaves human intelligence in awe. Rocks are no exception.
When I had to come up with an acronym for “Deciphering the magnetic record of planetary rocks using spacecraft and laboratory measurements”, PETRA came up naturally. You see: “DeciPhering the magnEtic record of planeTary Rocks using spAcecraft and laboratory measurements”. It makes total sense, right?
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The overall objective of this project is to help in deciphering the information about the formation and evolution of terrestrial bodies carried by the magnetic record of rocks. Here is how this works. The movement of the electrically conducting, fluid portion of a planetary core generates a magnetic field of planetary scale through a process known as dynamo. The dynamo magnetic field magnetizes the crust of terrestrial planetary bodies. The property of rocks to retain this magnetization over time periods that can extend up to billions of years provides us with a record of the past dynamo magnetic field, known as the paleomagnetic field. Moreover, crustal magnetization gives rise to a secondary magnetic field, known as the crustal magnetic field. The strength, geometry and evolution over time of planetary paleomagnetic and crustal magnetic fields are directly related to the structure, composition, and thermal state of the planetary bodies’ deep interiors, to surface processes such as hydrothermal activity and meteor impacts, and to atmospheric and climate evolution. Therefore, studying the paleomagnetic and crustal magnetic fields as these are recorded by planetary rocks opens a window into the deep interior and the geological past of a planetary body.
We can study these magnetic records at a variety of spatial scales, ranging from hundreds of kilometers down to micrometers. Each spatial scale offers a different perspective. Magnetic records spanning hundreds of kilometers are provided by spacecrafts whose magnetometers pick up on the magnetic signal of planetary crusts. Magnetic records of cm-scale rock samples are studied by means of laboratory rock magnetometers. Magnetic microscopes measure the magnetic signal of single crystals. For this project, I relied on magnetic field data of all these spatial scales.
—————————————————————————————————————————————————————In this project, I focused on the primitive magnetic field of Mars and of the Moon but the methodologies developed and used in this project can be applied to any terrestrial body, whether a planet, a moon or an asteroid. Ongoing and upcoming magnetic field spacecraft missions (e.g., Psyche and BepiColombo, spacecrafts on their way to asteroid Psyche and planet Mercury, respectively) and sample return missions (e.g., OSIRIS-REx, which recently delivered to Earth samples from asteroid Bennu, the program Artemis, expected to return new lunar samples on Earth in the next few years, and the sample return phase of the Mars 2020 mission expected to bring to Earth the first oriented samples from Mars over the next decade) create an unprecedented opportunity to use crustal magnetism and paleomagnetism to drastically expand our understanding of planetary formation and evolution.
The work I did on Mars, is discussed here. The work I did on the Moon is discussed here. As more results of these studies get published, I will update the respective webpages with more details.
In collaboration with Sabrina Sanchez, we put together a comic book about part of my work on Mars. Please check it out here and feel free to share it and spread the word. We would love to have this reach a wide public and especially young audiences.
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The work initiated by this project is ongoing but with the project officially finished, I feel the need to express my gratitude to everyone I worked with, befriended and received support and guidance from, from the moment I got the idea of applying to this Fellowship, up to now. It takes a village.