1 The Mars Relay

The UHF Mars Relay onboard the orbiting Mars Global Surveyor spacecraft provides data relay capability for landed systems on Mars. The Relay was employed to provide exclusive data return for the New Millennium Deep Space Two Mars Microprobes and backup data return for the Mars Polar Lander near the South Pole of Mars during the period of landed operations beginning 2000-12-03. Although the Mars Relay was active at the time of expected landed operations, no data from either surface mission were return through the Relay due to failure of both landed systems. However, the 1-watt signal, from the Relay in low circular polar orbit about Mars, was exploited, using the SRI 46-meter Antenna at Stanford University, to probe the Martian atmosphere and ionosphere at UHF frequencies. Internal telemetry and independent Earth-based observations on the Mars Relay UHF signals confirm the relay's functionality. The Mars Relay continues to represent a telecommunications resource for data return from Mars. 2 1