Near earth asteroid rendezvous (NEAR) spacecraft solar conjunction experiment

The Near Earth Asteroid Rendezvous spacecraft was occulted by the solar dis k on Feb. 19, 1997, During the period between Feb. 7 and March 3, 1997, the spacecraft X-band telecommunications system was used to carry out a combin ation of engineering and radio science measurements through the solar coron a, The engineering results of that experiment are reported. Statistics on t he uplink command acceptance rate and downlink frame error rate show that t he performance of both links was reasonably good at a sun-Earth-probe (SEP) angle of about 2 deg, but degraded rapidly as the angle fell to 1 deg, Rep resentative open-loop receiver data show moderate dips in downlink carrier amplitude (up to 4 dB) at an SEP angle of 3 deg and large dips in downlink carrier amplitude (up to 15 dB) at an SEP angle of 1 deg, Recommendations a re given for future solar conjunction events, particularly in the area of g round receiver optimization, The experimental results provide a unique data set useful for the design of future planetary missions.