[X] My Assistant

[Airbag]

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:



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?

 DSS_43_qt_vr.mov ( 783.76K ) Number of downloads: 467


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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[Airbag]

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The front and rear of DSS-43:



The roads in the complex all have names that forum members would all totally understand and approve of. Here we are next to one of the signs, pointing at the locations of Voyagers 1 (Astro0) and 2 (Airbag). What, you mean you don't stand at intersections pointing at distant spacecraft too?!



Next was DSS-34, at the far end of the complex and at a slightly higher elevation which also made it a good place to look back at the entire complex. Here is a MER style pano of the site from that location; you can just see DSS-46 (more later) pointing straight up towards the left hand side, then (to the right) the 70m dish and then nearby DSS-34. The other 34m dish, DSS-45 is to the right of this pano and we did not get close to it. We did see it do a fast (it is all relative!) slew in elevation though. You can also see how the site is located in a valley.



From the brochure: "DSS-34 is a beam wave guide antenna. The 34 meter dish reflects signals from deep space to receiving equipment located underground.". On the picture below you can clearly see the wide wave guide and the locations of the reflectors. Note that this is very different from the other dishes of the complex, which have their RF equipment mounted on the dish itself. There are trade offs of course - losses incurred by the extra reflectors versus the weight and complexity of the having all the equipment as part of the moving dish structure.




We then headed out to DSS-46, a 26m dish, which has a really interesting history. It used to be located at Honeysuckle Creek, and for you Apollo fans this was the actual dish used to receive the TV signals from that first moon walk. Ignore the "Dish" from the movie of the same name, that was the Parkes (radio) telescope! I'm old enough to remember the name "Honeysuckle Creek" being mentioned on the live TV reports during Apollo days. Quite something, to now see that dish in person. This dish is no longer used, but Astro0 has great outreach and educational plans for it - that would seem to be a fitting retirement use for such a proud background.



Because things were relatively quiet Astro0 was able to guide us into a gallery overlooking the operations room. Well, if you have seen any IT type control room with people sitting at desks with many monitors in front of them, you know what it looks like. Except there are posters of space missions, and certificates of appreciations for helping missions, etc. :-) No cameras allowed there but one of the main screens was also echoed (a nice touch I thought) in the visitor centre - it showed the high level schedule for each of the dishes. As you can see, DSS-43 was in the middle of an 11 hour Voyager 2 tracking pass:



Back into the official visitor center for some refreshments, before Astro0 took us on a whirl wind tour of the exhibits. There was a lot to see and many really interesting exhibits - where to start? How about a full size MER model, set in a realistic Martian landscape? As we were talking about the MER mission various other visitors drifted by and listened in and ask questions etc. Some instant outreach - Steve S. would have been happy to see our enthusiasm and excitement for the MER mission in action!




Many other memorable exhibits...a sizeable chunk of Moon rock weighing 142.25grams (about a third of a pound!) from Apollo 11...



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