Voyager support at Tidbinbilla

John Saxon writes:

I started on Voyager with the launches in 1977 which we supported at Honeysuckle Creek station (which became DSS44 after the end of NASA's Manned space missions). We also supported the Viking Landers on Mars, the Helios spacecraft around the sun, the Pioneers launches and encounters with the outer planets, and many other projects. Later when Honeysuckle closed in 1981 many of us moved to what is now CDSCC (the Canberra Deep Space Communication Complex).

But the Voyager missions were gifts that just kept on giving!

For the first time those distant points of light orbiting the outer planets became separate new worlds, each with their own unique terrain and characteristics. Io, Europa, Ganymede and more at Jupiter, Google now tells me that the total number of Jovian satellites is now 67!. Then the (very) close up views of the rings of Saturn, with the rotating and woven patterns. Then the strangely tilted Uranus with its very faint ring system. Finally Neptune and the incredible finale of the Ice fountains on Triton... Today I read that Voyager one may have finally reached Interstellar space. A 33 hour round trip light time – the mind boggles!

As one of the primary ground stations, the planetary encounter periods were always busy, but by far the most labour intensive activity was keeping the Radio Science equipment fed with the massive glass reels of 1" magnetic tape. It always amazed me that so much information could be gained from the minute changes in the received spacecraft frequencies as the signal passed through the atmosphere of the body we were flying past.

24/25 January 1986 This Radio Science Data plot from JPL’s Frank Donivan, shows the variability of the received X Band signal as Voyager 2 was occulted by Uranus, and also by the planet’s (then recently discovered) ring system. Large, Larger. Scan: John Saxon.

During the Voyager 2 encounter with Uranus, Tidbinbilla and Parkes were arrayed to substantially increase the rates at which science data could be received from the spacecraft. This arrangement was known as the Parkes – Canberra Telemetry Array (PCTA).

This plot of expected data rates from Voyager 2 shows the impact of arraying Tidbinbilla (CDSCC) and Parkes. The leftmost curve shows data rates expected at Goldstone. The rightmost curve represents Madrid. The lower elevation of Uranus at Madrid would be a major factor in lower data rates. The central two curves represent the data rate at Tidbinbilla with and without the array with Parkes. It was because of this advantage that the Voyager 2 encounter with Uranus was timed to coincide with coverage by the PCTA. Plot courtesy of Doug Mudgway’s Uplink – Downlink.