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Pioneer 10 & 11 Spacecraft
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Pioneer 10 & 11 were launched in 1972 and 1973, respectively, to probe the asteroid belt, Jupiter, and Saturn. The spacecraft achieved sufficient speed to escape the gravitational pull of the solar system, and have now travelled to distances well beyond the orbits of Neptune and Pluto.
Some navigational information (the speed of the spacecraft along the line of sight) was obtained by measuring the Doppler shift of the downlink signal. The spacecraft did not have accurate frequency references onboard, so the downlink frequency was tuned by reference to the received uplink frequency.
The high gain antenna used by the spacecraft was 3 m in diameter, which provide a 3.3 deg beam at 2.3 GHz. The effective isotropic radiated power from the antenna was 70 dBm (about 10,000 W) from the 8 W transmitter (antenna forward gain of approximately 31 dBi). The downlink bit rate was between 16-2048 bps.
Due to the distance to the spacecraft and the declining power being created by their radioisotope thermoelectric generators, communications with Pioneer 10 & 11 (via NASA's Deep Space Network) has been lost since 2003 and 1995, respectively.
As of 2012, Pioneer 10 is moving at about 12,000 km/s with respect to the Sun, or about 4% of the speed of light. At that speed, its downlink signal at 2292 MHz would be Doppler shifted to 2200.0 MHz.
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Paired Frequencies |
| Frequency | Bandwidth | Use | Service | Table |
| 2110 MHz | - | Pioneer 10 & 11 uplink transmissions | Space Research | F |
| 2292 MHz | - | Pioneer 10 & 11 downlink transmissions | Space Research (deep space) | F |
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