The 1998 Mars Global Surveyor Solar Corona Experiment

The Mars Global Surveyor (MGS) spacecraft, launched on November 7, 1996, carries an experimental space-to-ground telecommunications link at 32 GHz (Ka-band) along with the primary 8.4-GHz (X-band) downlink used for operational MGS project activities. The signals are simultaneously transmitted from a 1.5-m-diameter parabolic antenna on MGS and received by 34-meter beamwaveguide (BWG) antennas located at NASA’s Goldstone Deep Space Communications Complex near Barstow, California. Relative signal strength data demonstrating the advantage of Ka-band over X-band as well as details of analysis of the frequency data were presented in previous articles. This article will focus on details of the Ka-band and X-band observations acquired during the May 1998 solar conjunction experiment at solar elongation angles below 3 deg. For the link study, the Ka-band data were recorded open loop using the full spectrum recorder (FSR), and most of the X-band data were obtained from the closed-loop Block V receivers of the operational Deep Space Network. In addition, a few selected passes were conducted where open-loop FSR data were recorded at X-band. Among the solar coronal effects on signal propagation presented will be intensity scintillation and spectral broadening. Also presented are frequency data results acquired using DSS 13’s experimental tone tracker.