  TUS (Tracking Ultraviolet Set-up), the first orbital detector of extreme
energy cosmic rays (EECRs), those with energies above 50 EeV, was launched into
orbit on April 28, 2016, as a part of the Lomonosov satellite scientific
payload. The main aim of the mission is to test a technique of registering
fluorescent and Cherenkov radiation of extensive air showers generated by EECRs
in the atmosphere with a space telescope. We present preliminary results of its
operation in a mode dedicated to registering extensive air showers in the
period from August 16, 2016, to November 4, 2016. No EECRs have been
conclusively identified in the data yet, but the diversity of ultraviolet
emission in the atmosphere was found to be unexpectedly rich. We discuss
typical examples of data obtained with TUS and their possible origin. The data
is important for obtaining more accurate estimates of the nocturnal ultraviolet
glow of the atmosphere, necessary for successful development of more advanced
orbital EECR detectors including those of the KLYPVE (K-EUSO) and JEM-EUSO
missions.
