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.
Instrument
PHT03
Temporal Coverage
1996-10-17T22:56:16Z/1997-02-14T08:38:13Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, DERMOTT et al., 1999, 'OBSERVATIONS OF THE EARTH.S CIRCUMSOLAR DUST RING', 1.0, European Space Agency, https://doi.org/10.5270/esa-1u2k7qw
