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

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The New ESA Meteoroid Model. Presentation at the COSPAR Scientific Assembly ... The model is based on COBE/DIRBE IR sky maps, Galileo & Ulysses impact counts, ... – PowerPoint PPT presentation

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


1
The New ESA Meteoroid Model Presentation at the
COSPAR Scientific Assembly Paris, 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

2
Another update of 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

3
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

4
More improvements conceived in 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

5
The bad service of 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

6
Global correlations along evolutionary tracks
7
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.)

8
The mass distribution at 1 AU and the dynamical
regimes
Grün et al. (1985, Collisional balance of the
meteoritic complex, Icarus 62, 244-272)
Poynting- Robertson effect
Planetary gravity, intraparticle collisions
9
Big meteoroids from asteroids
  • Themis-Koronis families
  • Eos-Veritas families
  • The rest of the asteroid belt

10
Small dust grains from asteroids
  • Themis-Koronis families
  • Eos-Veritas families
  • The rest of the asteroid belt

11
Big meteoroids in the region of close encounters
with Jupiter
  • Tisserand parameter T3.00
  • Tisserand parameter T2.98
  • Tisserand parameter T2.94

12
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

13
Goodness of fit the 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)
14
Goodness of fit the IR sky scan at 90 elongation
15
Goodness of fit the in-situ impact counts
  • Spin-averaged flux measurements with Galileos
    DDS are best reproduced by the new model

16
Goodness of fit the 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

17
Goodness of fit the lunar micro-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

18
The orbital distributions of 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

19
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
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