Out-of-ecliptic dust

Predictions of the number density of interplanetary dust particles out of the ecliptic plane are derived from model computations by adjusting the parameters to the run of brightness of the zodiacal light in the ecliptic plane and at right angles to the Sun from the ecliptic plane to the ecliptic pole. Within the limits of the simple models, surfaces of equal number density are presented. The number density of zodiacal dust particles is not expected to fall below 20% within 0.5 AU above the earth's orbit. The use of space probes in and out of the ecliptic is discussed, and the possibility of discriminating between different dust distribution functions by means of out-of-ecliptic probes is demonstrated for a space probe in an orbit of 1 AU radius and 30 deg inclination with respect to the ecliptic plane. (FR)