Optical detection of local interstellar particles during an out-of-ecliptic mission

Abstract

THE contribution to the zodiacal light (ZL) by interstellar grains has been estimated1–3, but, as suggested here, new observations and analyses of the ZL and of the local interstellar medium provide a firmer basis for placing limits on the brightness of the interstellar (IS) relative to the interplanetary (IP) component. The proposed NASA/ESA ‘out-of-ecliptic’ (or ‘solar polar’) mission4 provides the best and perhaps the only observational method to distinguish between these two components.