THE ORA OCCULTATION RADIOMETER ON EURECA - INSTRUMENT DESCRIPTION AND PRELIMINARY-RESULTS by Arijs, E, Nevejans, D, Fussen, D, Frederick, P, Vanransbeeck, E, Taylor, F, Calcutt, S, Werrett, S, Hepplewhite, C, Pritchard, T, Burchell, I, Rodgers, C