Nowadays, more than 17; 000 objects greater than 10 cm in diameter are tracked and available in public catalog. Just nearly a thousand and a half are active spacecraft. In low Earth orbit (LEO), the increasing of Cube-Sat missions launched in last years is contributing to the growth of the space object population. Furthermore, large constellations to LEO are under development. Such constellations will lead to an unprecedented, step increase in the number of satellites in LEO. Consequently, to prevent the generation of debris in the short-term and the growth of the debris population over the longer-term is mandatory to avoid Kessler syndrome. Therefore, due to the continuous growth of number of operative satellites and the consequent risk of impact among them, an improvement in the observation is constantly demanding. The presented solution to provide a reliable and timely response in case of contingencies is the development of a worldwide sky-coverage network. In the framework of the Italian Space Agency (ASI) – Sapienza University of Rome Agreement (N.2013-078-C.O) for scientific cooperation at the Broglio Space Center (BSC) in Malindi (Kenya), S5Lab research team is developing a network of optical observatories. The presented thesis deals with the development of the network composed by an Italian observatory named MITO (Mid-latitude Italian Observatory), located near Rome and an equatorial observatory called EQUO (Equatorial Italian Observatory). The combinatorial explosion in the number of intervals to be scheduled has been caused by the increasing number of space debris to be observed with optical ground station. Therefore, new scheduling approach are needed to provide a solution to the new requests. In the framework of the Agreement between Italian Space Agency (ASI) and National Institute of Astrophysics (INAF) Supporto alle attività IADC e validazione pre-operativa per SST (N.2015-028-R.0) a scheduler has been developed to manage the network. The presented thesis outlines the developed software called NICO (Networked Instrument Coordinator for space debris Observations) designed to allocate visibility windows to each optical sensor of the network by solving priority conflicts of the scheduling tasks. NICO goal is the harmonization of the different requests by taking care also of external limitations such as astronomical constraints and weather conditions. The development of a network of observatories and a scheduler to manage and organize the data acquisition routine has triggered the problem on how to manage the acquired data. Due to the increasing of the number of the observatory involved in data acquisition and the number of taken images per night, a new automated image processing tool for light-curves measurements was needed. This thesis presents the development and application of the automated software designed to process light curves acquisition. These are used to determine the dynamical state of the target in terms of attitude by processing the light reflected from the metallic surface of the object. Rapid changes in brightens of the response are investigated to reconstruct rapid changes in the attitude in the scale of a second or less. These data are extremely valuable to detect and investigate the attitude of an orbiting object and its evolution especially for future Active Debris Removal (ADR) missions.
|Titolo:||Optimal planning of space surveillance network and automatic data processing|
|Data di discussione:||22-feb-2018|
|Appartiene alla tipologia:||07a Tesi di Dottorato|