Via the wonders of this forum and intercontinental jet travel I had the opportunity and great pleasure to meet Astro0 (0 not as in "zero", but as in "naught" - get it? I didn't!) in person at the Canberra Deep Space Communication Complex at Tidbinbilla. We'd probably think of it as a Deep Space Network (DSN) tracking station though. I was going to be on vacation in Canberra and we had exchanged some forum messages before hand, and Astro0 kindly invited us to the DSN site for a behind the scenes tour. Well, now there was an offer I could not refuse!
So together with my wife and some members of the family we were staying with in Canberra we headed off to the DSN site, which is about half an hour away. The road winds through gently rolling hills and green meadows, it looked almost like England...except that it had rained a lot just before we arrived, and normally this is all dry and brown. And there are kangaroos. Many of them! Then all of a sudden we came to another valley and there they were...the dishes, gleaming white. They are in the valley to shield them from terrestrial interference; the higher horizon is not so much a restriction for deep space communications as it would be for near Earth operations.
My first thought, I have to admit, was "So where is the 70m dish"? as I could not see any really big ones. But it was right there in front of me - the size of the thing is just so hard to interpret without anything nearby to compare it with. More on that later. Note the interesting sign near the entrance:
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We met Astro0 in the visitors center, and after initial introductions he led us out through a "secret" door (well, the story sounds better this way) to the complex itself and we picked up our badges and without further ado headed off to DSS-43, the 70m diameter dish, which is the largest of its type in the Southern Hemisphere. Astro0 told us all about the difficulties in maintaining these huge dishes and how the main azimuth bearing was being replaced (a tricky and complex operation) on another such DSN dish elsewhere. I should note that the Canberra DSN site has an enviable reputation for the best uptime and communications record, and they are justifiably proud of that!
The 70m dish is just too big to comprehend. You stand under it, and without anything else to compare it with nearby it is just so hard to tell just how big it is. At the time we were there is was doing a long tracking pass of Voyager 2. If you looked very, very carefully, you could see the entire dish and support structure rotate in a counter clockwise direction as it was tracking Voyager 2. That also told us we were in the Southern Hemisphere, as if the kangaroos and Astro0's accent weren't enough of a clue :-).
But when you think about it (as we did after Astro0 pointed it out to us), it is not actually the dish that was moving - since Voyager 2 is so far away that it is essentially at rest with respect to the background stars, what we were seeing was the Earth's rotation, and the dish was actually one of the most un-moving things around! So what is it like to stand underneath that 70m dish?
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There is a complex structure at the focal point of the dish; that tower (containing various receivers and transmitters) looks to me like an upside down rocket engine and is about 5 storeys tall, to give you some sense of the size of the dish.
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