The esef instrument: A European facility for exposing active and passive particle detectors in low earth orbits

Abstract In the context of dust collections in space, the COMET experiment (Collecte en Orbite de Matiere ExtraTerrestre) was proposed in 1982 and has been accepted in 1985 in the framework of the Soviet-French space cooperation program. The idea of such an experiment was to install collectors inside hermetic boxes, to have these boxes mounted outside a space station, orbiting the Earth and to have the capability of chosing the date and duration of the collection. In February 94, it has been proposed to fly an improved version of this instrument, as part of the payload of the EUROMIR 95 mission. Renamed as the European Space Exposure Facility (ESEF), it carries experiments from several principal investigators (PIs). These experiments have been designed to analyse in real time some parameters of the encountered particles and to collect material, both of terrestrial and extraterrestrial origin, to be brought back to the Earth at the end of the mission. Three types of collecting material are used: high purity metals, foams and silica aerogels. All grains down to submicron sizes can be possibly identified by such a variety of collectors; the presence of very low density collectors, like the foams and silica aerogels, should permit the collection of grains least modified, one of the primary goals of this investigation. This paper refers to the description of the instrument and of the various experiments.