ИСТИНА

The determination of the exact characteristics of the present flux of interplanetary matter entering the Earth's atmosphere from ground-based or space-based optical observations is challenged by the complexity of the mechanics of atmospheric entry of small bodies. Spectroscopic analysis in particular shows great variations in lines from both atmospheric components and body ablated components from meteor to meteor, depending both on characteristic of body and its entry trajectory. The METEOR project aims at putting in orbit one or several detectors dedicated to the observations of atmospheric entries of small bodies (cm-sized to 10m-sized), with optimized and continuous conditions of observation and no impediment from lower layers of atmosphere. In preparation of this project, we are developing a simulator with two objectives. The first objective is the determination of the number of expected detections in function of the observations parameters. For this purpose, we have considered the existing data about the size repartition of meteoroids, and of the characteristics influencing their luminosity. Reasonable assumptions could be made on the number of events occurring in our detector's field of view and whether they would be bright enough to be spotted. This assessment was made considering an off-the-shelf CAMERA developed for this purpose: the SPOSH camera. Possible directions for improvements will be also discussed. The second objective is to assess the feasibility of predicting the characteristics of a meteoroid from the observations, and which constraints should be set on our detectors to achieve sufficient accuracy in this regard. Nature (rocky/icy or metallic), mass and velocity are the parameters to be determined in priority from the trajectory and luminous behaviour during the entry phase. If possible, these parameters may be used then to infer the orbital characteristics of the meteoroid and trace it back to its parent body. It appears that such a mission would allow for unprecedented number of detection of meteors, permitting numerous analyses of entries of bodies with different characteristics and thus a vast sampling of objects, which would complement in-situ analysis of parent bodies. Especially, spectroscopic analysis including UV domain would bring a wealth of data on the mechanics of atmospheric entry on Earth, which could be used to understand similar phenomena in atmospheres of other bodies in the solar system. This knowledge would help preparing future missions including atmospheric entries and using meteor phenomena as natural probing of atmospheric layers.