The physical properties and the number density of micrometeoroids and orbital debris are important parameters of the space environment. High-velocity interaction with spacecraft can be of serious concern for the operation of long-lived space structures and for man operations in space. Two experiments devoted to the detection of microparticles were flown recently. They were based on capacitor-type sensors that allowed the detection of particles larger than 1−3 μm in diameter. One of the experiments, the First Orbital System for an Active Detection of Debris, on the International Space Station was retrieved after space exposure. It was then possible to get additional data and to assess the behavior of the sensors. Laboratory analyses provided clues on the composition and the origin of the impacting particles. The second experiment, the Second Orbital System for an Active Detection of Debris, was deployed on the Satellite for Scientific Applications-D on a sun-synchronous orbit. The behavior of the experime...