“…Since the pioneering work by Benson and Linsley, different aspects of registering UHECRs from space have been studied in much details, see, e.g., [6,7] and a whole number of projects have been suggested, among them AIR WATCH [8], OWL [9,10], EUSO and later JEM-EUSO [11] (see also these proceedings) and Super-E U S O [12] but none of them has been implemented yet. The only fully implemented orbital detector of UHECRs is TUS [13,14], which was developed in Skobeltsyn Institute of Nuclear Physics of Moscow State University (SINP MSU) in cooperation with several Russian and foreign institutions following the original reflector type telescope scheme suggested by Benson and Linsley. Being scheduled for launching in late 2015 from the Vostochny Cosmodrome, TUS is not expected to make a breakthrough in UHECR physics because of its pretty modest technical parameters [15] but will serve as a pathfinder for the new class of UHECR experiments.…”