Magnetic Properties of Large Meteorites: Analogy to Asteroid Signatures Peter Wasilewski2 and Gunthe

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Magnetic Properties of Large Meteorites Analogy
to Asteroid SignaturesPeter Wasilewski2 and
Gunther Kletetschka1and M. Acuna 1Code 921,
2Code 691, NASAs Goddard Space Flight Center,
Greenbelt, Maryland, USA

• Magnetism of Eros
• Objective was to establish existence of magnetism
  
• Asteroids are the parent bodies for most
  meteorites reaching the Earth
• Composition matches LL chondrites
• Magnetism is related to ?-kamacite (?-taenite (7 Ni), and ?"-tetrataenite (43-52
  Ni)

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Eros limit
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Eros and Large Meteorites
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Meteorite magnetism

• The smallest scale for which the magnetization is
  homogenous and is chondrule size(1mm).
• Some chondrules acquired very intense natural
  remanent magnetization associated with
  extraordinary conditions of remanence acquisition
  of unknown nature
• Chondrules, however, are randomly oriented
• Smaller meteorite samples are more magnetic
  because they dont randomize completely the
  remanence direction.

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Conclusions

• Absence of magnetic moment on 433 Eros may not be
  surprising and can be predicted from the
  meteorite record.
• Non-magnetic nature of Eros is due to absence of
  significant homogeneous magnetic field during the
  agglomeration of the asteroid from smaller
  fragments.
• Small scale (1mm) fragments (chondrules) can be
  strongly magnetic, but randomly oriented in
  respect to each other.