Field and wave measurements aboard the Aureol-3 spacecraft

In the Soviet-French Arcad-3 project, 3 experiments TBF-ONCH, TRAC and ISOPROBE are carried out on board the Aureol-3 satellite to measure the AC and DC electric and magnetic fields and waves. Several modes of telemetry, real time and memory regimes are available for data transmission. TBF-ONCH is devoted to the measurement of 3 components of the DC electric field, 2 electric and 3 magnetic components of the waves. In one mode of the real time telemetry these 5 components are transmitted simultaneously in the frequency range 10 Hz-1.5 kHz in order to be able to determine the wave normal directions of natural emissions and to localize their sources. In the second mode, morphological studies of saucers, chorus, hiss and triggered emissions can be undertaken using the wide band transmission (70 Hz-16 kHz) of any one of these 5 components with the possibility of periodically changing the transmitted component every 4 seconds or keeping the same one during all the pass. TRAC makes use of the on board 3 axis flux gate magnetometer to perform a fine measurement of the magnetic effects of the currents flowing in the vicinity of the spacecraft either in the ionosphere or along the magnetic field lines, with a resolution of ～ 12 nT and in the frequency range from DC to ～ 20 Hz. One component of the HF electric field (0.1–10 Mhz) is measured by ISOPROBE (see companion paper). Examples of inflight measurements from the above instruments and their presentation on microfiches are shown. Some new phenomena are emphasized and briefly discussed.