First test of the NOZOMI radio science system in actual space flight Original Research Article

The Japanese NOZOMI spacecraft (S/C) launched on the 4th of July, 1998 was equipped with a coherent dual frequency Radio Science System (RSS) to explore the Martian atmosphere and the solar wind plasma by the radio sounding method. Several communication operations were performed in order to test and calibrate the RSS during the cruise phase of the flight to Mars. S- and X- band signals emitted by the S/C were received and recorded at the Usuda tracking station (Japan). Analysis of the data processing results revealed the influence of the S/C spin on all signal parameters. In particular the S/C spin shifted the frequencies of both the S- and X- band signals, destroying their coherency. It was shown that the effect of the spin stabilizing system can be removed from the final occultation results and the Nozomi S/C can be successfully used in radio occultation experiments.