For fifteen years, GAUSS (Group of Astrodynamics of the "Sapienza" University of Roma) has been designing, manufacturing and launching four University Satellites (UNISAT) at the School of Aerospace Engineering of Roma. In recent years, GAUSS has also been involved in optical space debris observation, through the creation of the first Italian observatory, completely dedicated to space debris monitoring. In this context, GAUSS students have been analysing the feasibility of a formation flight mission in order to detect space debris, taking advantage of an observation above Earth's atmosphere. This paper will focus particularly on the detection of objects along MEO orbits. The concept is to use optical devices to make observation and orbit determination with the use of a formation of two or more microsatel-lites (depending on the error constraints) taking pictures of the same area from different locations and making a reconstruction of the position of the object using angular measurements. These are obtained through a comparison of the images taken from multiple points of observation by the satellites. Two different strategies of orbit reconstruction are analysed: the first one consists of taking different pictures in order to estimate the position at distinct instants of time; the second one involves capturing a single picture from each satellite, with a higher shutter time so that the position and velocity can be estimated analysing the trail of the object's stripe in the picture. Particularly in this case an accurate attitude control is needed; in fact, to avoid stars generating excessive stripes on the pictures, spacecraft attitude must be kept as fixed as possible, with respect to an inertial reference frame. The paper also describes the choice of the optical configuration and CCD sensors needed in order to obtain an optimal image acquisition, taking into account the weight and the dimensions of the microsatellites. In order to avoid eclipses, the satellites will be placed in a formation along a Sun-synchronous dawn-dusk orbit.The satellite's attitude control will be attained with the use of eight pulsed plasma thrusters.
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