The New ESA Meteoroid Model Presentation at the COSPAR Scientific Assembly Paris, France, 1825 July

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The New ESA Meteoroid ModelPresentation at the
COSPAR Scientific AssemblyParis, France, 18-25
July 2004
William J. Baggaley, David Galligan University of
Canterbury at Christchurch, New Zealand Markus
Landgraf, Rüdiger Jehn ESA/ESOC, Germany

• Valeri V. Dikarev
• Max-Planck-Institut für Kernphysik, Germany
• Astronomical Institute of St.Petersburg
  University,Russia
• Eberhard Grün
• Max-Planck-Institut für Kernphysik, Germany
• Institute of Geophysics and Planetology,
• University of Hawaii

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Another updateof the ESA meteoroid model

• Delivered in 2003, seven years after release of
  DUSTMOD (Staubach)
• Was accomplished at MPI-K, DE
• A dedicated radio meteor survey was performed,
  its data reduced at UOC, NZ
• The project was supervised by ESOC

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Reasons for a new model

• A bug in reduction of the Harvard Radio Meteor
  Project data that was the most important base for
  the previous models (Divine, Staubach)
• More recent reduction procedures revealed many
  high-speed meteors evaded the previous surveys
• New high-quality data were available for
  incorporation in the meteoroid model
• The software to predict meteoroid fluxes on
  spacecraft was slow

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More improvements conceivedin the course of the
update

• Remove the vital limitation of the previous
  models, the assumption of mathematical
  separability of the orbital distributions
• Apply knowledge of the orbital evolution of
  meteoroids to support the construction of the
  orbital distributions

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The bad serviceof separability assumption

• The true orbital distributions are not separable
  in the form f(a,e,i)f(a)g(e)h(i)
• 2-D illustration

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Global correlationsalong evolutionary tracks
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Our review of the orbital evolution of
interplanetary meteoroids

• Sources are comets and asteroids
• Governing forces are gravity of Sun and planets,
  and the Poynting-Robertson effect
• Sinks are the Sun and mutual collisions between
  meteoroids
• No satisfactorily complete physical model existed
• Invaluable insights by Briggs, Leinert, Dermott,
  Ishimoto, Gorkavyi, Liou, et al.
• (Great that Eberhard Grün was leader. V.D.)

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The mass distribution at 1 AUand the dynamical
regimes
Grün et al. (1985, Collisional balance of the
meteoritic complex, Icarus 62, 244-272)
Poynting- Robertson effect
Planetary gravity, intraparticle collisions
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Big meteoroids from asteroids

• Themis-Koronis families
• Eos-Veritas families
• The rest of the asteroid belt

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Small dust grains from asteroids

• Themis-Koronis families
• Eos-Veritas families
• The rest of the asteroid belt

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Big meteoroids in the region of close encounters
with Jupiter

• Tisserand parameter T3.00
• Tisserand parameter T2.98
• Tisserand parameter T2.94

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Dust leaking from the region of close encounters
with Jupiter

• Initial Tisserand parameter T3.00
• Initial Tisserand parameter T2.98
• Initial Tisserand parameter T2.94

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Goodness of fitthe IR sky maps

• The infrared intensity maps built by COBE/DIRBE
  are reproduced quite good, shown is the sky
  through 60?m-filter, we took the maps obtained
  through 5, 12 and 25?m-filters as well into
  account

(Calculatum)
(Observatum)
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Goodness of fitthe IR sky scan at 90 elongation
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Goodness of fitthe in-situ impact counts

• Spin-averaged flux measurements with Galileos
  DDS are best reproduced by the new model

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Goodness of fitthe in-situ impact counts - 2

• The new model reproduces very well the impact
  rate recorded by the Ulysses DDS during the
  high-speed ecliptic plane crossing

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Goodness of fit the lunarmicro-crater size
distribution

• We restored the original crater size distribution
  from the model by Grün et al. (1985)
• We used the relative mass distribution from the
  same model
• We obtained a very good fit of the model to the
  crater size distribution, simultaneously with the
  other data sets

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The orbital distributionsof the radio meteors

• We could not simultaneously fit to the orbital
  distributions derived from the AMOR survey and to
  the COBE IR maps

• The AMOR reduced meteor orbital distributions
  contain probably too many particles on highly
  inclined prograde orbits

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Conclusions

• A new model of meteoroid fluxes in interplanetary
  space was built
• The model is based on COBE/DIRBE IR sky maps,
  Galileo Ulysses impact counts, lunar
  micro-crater counts and AMOR radio meteors
• The model employs knowledge of the orbital
  evolution of meteoroids to increase the power of
  extrapolations of existing observations
• Still considerable discrepancies remain between
  the model and the AMOR results, but the AMOR
  distributions are obviously incompatible with
  another data set included (namely, COBE/DIRBE)
• We are looking for the explanation of the
  discrepancies