Ricerc@Sapienza

In recent years, the increase in space activities has brought the space debris issue to the top of the list of all space agencies. The fact of there being uncontrolled objects is a problem both for the operational satellites in orbit (avoiding collisions) and for the safety of people on the ground (re-entry objects). Optical systems provide valuable assistance in identifying and monitoring such objects. The Sapienza Space System and Space Surveillance (S5Lab) has been working in this field for years, being able to take advantage of a network of telescopes spread over different continents.

Space Situational Awareness (SSA) has become a maor issue in the international debate due to the growth of commercial space activities and the correspondent increase of obects orbiting around the Earth. As no State can conduct a comprehensive monitoring of the whole space environment and orbits, SSA requires a strong international cooperation both on the technical aspects of surveillance and on the sharing of information acquired. In this sense, States conclude bilateral agreements and public-private arrangements to promote wider exchange of information.

Optical observations represent a passive method for space debris tracking and monitoring. Although being con- strained to limited time intervals, e.g. when the target is in sunlight and the observatory is in darkness, a debris observatory network distributed over multiple locations can improve the observational interval and favor the data integration for more consistent and significant results.

The interest in determining the attitude of an orbiting object has grown significantly in recent years. Besides being one of the key parameters needed to obtain a precise orbital determination, the attitude is also crucial in the perspective of planning a space debris removing mission. In this paper, we present a method to retrieve the attitude of an orbiting object, based on a virtual reality simulation together with a global optimization. The attitude will be determined using the object's lightcurve derived information, i.e. the total reflected light variation in time.