Congratulations to Kristian Kristiansen on passing his PhD viva on 2 December.  His external examiner was Andrzej Maciejewski (Zielona Gora, Poland), the internal was Claudia Wulff (Mathematics), and his supervisors were Phil Palmer (Surrey Space Centre) and Mark Roberts (Mathematics).  Kristian’s viva was on the “Relative Motion of Free and Tethered Satellites”.