Clara Maurel: Bridging spacecraft magnetometry investigations and laboratory experiments
Channel: Institute for Rock Magnetism
Date: 2021-06-05

12th Institute for Rock Magnetism Conference

Session 4: Advances in Instrumentation and Methods
Conveners: Julie Bowles (University of Wisconsin-Milwaukee) and Sonia Tikoo (Stanford)

Title: Bridging the gap between spacecraft magnetometry investigations and laboratory experiments using iron meteorites

Authors: Clara Maurel (1), Jérôme Gattacceca (2), Elise Clavé (3), Minoru Uehara (2), Timothy J. McCoy (4) & Benjamin P. Weiss (1)

(1) Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
(2) CNRS/Aix Marseille Université, CEREGE, Aix-en-Provence, France
(3) Université de Bordeaux, Centre Lasers Intenses et Applications (CELIA), France
(4) Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington DC, USA

Abstract:
Asteroids and meteorites are fragments of our solar system’s first planetary bodies. Similar to Earth, some of these “planetesimals” underwent differentiation and powered magnetic fields by the motion of their liquid metallic cores. Many studies conducted on meteorites show that some of them are magnetized and carry the record of their parent body’s magnetic field. On the other hand, despite the fact that asteroids are samples of the same planetesimal population as meteorites, none of the magnetic investigations so far conducted by spacecraft on asteroids or comet have found reliable evidence for a magnetized small body. To explain this apparent discrepancy, it has been hypothesized that because magnetization decreases with sample size, it would be inherently undetectable at asteroid scale. Here, we test this hypothesis by combining measurements of iron meteorites at multiple size scales, from the millimeter to the meter. In particular, we use a portable magnetometer array designed to accommodate meter-size samples that cannot be taken out of their storage facility. This work shows that the magnetization need not be reduced to zero as size increases but instead may asymptote at a non-zero value. Consequently, size alone may not necessarily prevent asteroid magnetization to be detected; multiple other factors may, however, hinder the detection.