Contents of: VI/111/./abstract/SDERMOTT_ETRING_1.abs

The following document lists the file abstract/SDERMOTT_ETRING_1.abs from catalogue VI/111.
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Using ISO we propose (a)to confirm the existence of the trailing/leading
asymmetry of the zodiacal cloud discovered by us using the IRAS data,
(b)to determine the variation of this asymmetry with the longitude of
the Earth, and (c)to search for radial structure in the circumsolar ring
of interplanetary dust particles in resonant lock with the Earth, that we
consider accounts for the asymmetry. We have determined (Dermott et al.,
Nature, 369, 719-723, 1994) that a large fraction of the asteroidal dust
particles spiral in towards the sun due to radiation drag forces, become
trapped in resonances and form a circumsolar ring in which the Earth is
embedded. This ring contains a cloud of dust that appears to trail the
Earth in its orbit and produces a peculiar observational asymmetry, namely,
the flux observed behind the Earth in its orbit (trailing direction)
appears to exceed that observed in front of the Earth (leading direction).
Because the IRAS data have significant calibration uncertainties, ISO has
a unique opportunity to confirm the existence of the trailing/leading
asymmetry and to determine the structure of the ring. Measuring the
asymmetry will allow us to place constraints on the size distribution of
asteroidal particles near the Earth. However, variations in flux due to
the longitudinal variations in the amplitudes of the IRAS solar system
dust bands will have to be subtracted. We have already generated precise
models that account for the dust band contribution. In addition, our
ability to model the orbital evolution of asteroidal dust will allow us
to relate the measured trailing/leading asymmetry to the structure of the
circumsolar ring. We also propose to scan the trailing dust cloud in the
radial heliocentric direction. By varying the elongation angle, we will
determine the radial structure of the ring produced by particles trapped
in discrete resonances. Our proposal will be very effective in providing
an important confirmation of the circumsolar ring as well as providing
new insights into the dynamical structure of the zodiacal cloud and has
the great advantage of a 100% viewing probability for most of the mission.