Saturday, August 30, 2014

the ARO tour

I captured the Algonquin Radio Observatory tour notes in my Psion.

We started our tour in the parking lot. Dr. Brendan Quine reminded us we should have sunglasses.

The dish is 46 metres or 150 feet in diameter. I asked how much it weighed. The dish is 1500 tons. Brendan said the accuracy was incredible. The National Research Council built it and operated it from 1965 to 1985. Then 12 buildings were removed leaving 12. The large array was also removed. Then NR Can operated the telescope until they broke it in 2007.

Thoth, a fully private company, took over. It took years to bring it back to life. Thoth has about 20 full-time and part-time employees plus some consultants. Chris said people have to be willing to do everything... Now Thoth provides quality radio services. Rate: $600/hour. Thoth, in Greek mythology, was the god of knowledge, wisdom, symbols, and maintained the Universe. We moved indoors to an old electro-mechanical room. There was the ibis logo on a banner.

Brendan talked for a time about pulsars and GPS. A pulsar reference frame is used to measure where things are located on the planet. A pulsar time pulse is better than any atomic clock. The ARO has 1mm accuracy. It was invented here, VLBI or very-long-baseline interferometry, in 1965. You have to sift through a lot of noise. EVLBI (electronic) also invented here. Thoth is working on IVLBI (internet).

The ARO site became the most well-mapped location on earth. The GPS system is a US-based with military ties. He pointed out the prime geodetic (landmark) white post pillar. Thoth provides data to NASA who in turns it to the US government. 150ms ping on L-band. The fourth GPS satellite provides time reference. I quickly typed my notes on the little keyboard. I don't know if they'll make sense.

Headed to control room. Awesome. Dish just outside the window. Moments of movie Contact synchronicity. Brendan pointed out the old control panel. Mentioned that it is clearly visible in the NFB film. Now they use a programmble control unit, computer-based, basically fly by wire. Chris had fired up a couple of PC screens as we were walking in.

There was a question about backup power. He said they do have generators but generally don't run in a power cut.

Discussed looking at things a long ways away, looking for plane radiation, which is reflected to focus in the cabin above the dish. Not unlike a visual instrument. Lambda over 8 preferred. 1mm RMS. Each plate was individually bent, 36 pieces. Mentioned some of the companies from the construction. Freeman Fox. Rank Mann Mechanical. Grubb Parsons, of course. Ship building companies. Even he was impressed that it occurred a mere 15 years after the world war. Modern pre-amp's are incredible, only 25 K. Mixing is used for noise reduction. It is 200 metres between focus cabin and sample room.

There is a campaign to measure the size of a pulsar. Mentioned the Rayleigh limit. India has twenty 25m antennas, Germany has a 100m, UK has a big one. This will permit a baseline of 8000 km. But it is still not enough. Lensing may help. IBM sponsors them, helps with computing and storage. 4 tb! They'll be able to push 40 gb in the new optical fibre recently installed. USA is cutting funding by half, so US radio observatories will going commercial, like Thoth. They are committed to providing high-quality data with live diagnostics for verification and that can be inspected immediately. They will inject engineering data.

We went downstairs to the "time lab." We huddled in the thermal room/Faraday cage to examine the hydrogen maser. Provided by NASA, about a cost of about $1 million. Canada has about 5, made by Hopkins University. He emphasised that hydrogen very accurate for "short" projects, like one-night pulsar measurements. Very accurate. 1 in 1015. Pointed out the mauve colour of the hydrogen emission. The most interesting factoid: it doesn't need to be synced with other atomic clocks. It's more about time signatures. Reminded me of occultations.

Reminiscent of SNOLab, we travelled the dark underground tunnel to the antenna.

We emerged in the basement of the pedestal. The base goes into bedrock, the Canadian Shield, for stability. It was built somewhat close to Ottawa so to show off to the dignitaries, for the low water effect in winter, and that it was near the train.

Brendan explained that the ARO is one of 17 locations used to measure gravity. Reminded us that the land's elevation is changing about 10 cm all the time, it's dynamic, of course. Plastic.

Headed up one level. Brendan said this will be the new "interpretative" level. Showed some students experiments. When Thoth took over the ARO, it was broken. In many ways, including water systems. But the worst damage was to the main antenna. Over the years, lady bugs had gathered in the gearboxes and bearings and their hard shells had slowly damaged things. They fixed the gearboxes. But the final blow was when the dish was driven at speed into the end stop causing catastrophic bearing failure. Even though designed for 250 ton static loads with double rollers, the bearing and race was severely damaged.

SKF (Germany) provided bearings, with the latest versions made in China.

A Discovery Channel segment shows some of the bearing work.

We spotted a dial phone and 5¼" floppies on desks. Bernard said current students had never seen these things. I felt old.

He showed us some more servo-mechanical, 600 volt equipment. I missed the reference but the builder had a connection to German dams. I recalled the Ice Pilots NWT show where Arnie demonstrated the skipping barrel bomb drop.

Picked up our hard hats.

We entered the azimuth deck or track room. We saw the central pivot point and the four motors that turned the turret. They feature integrated jacks. We clearly saw the large metal ring that the upper assembly rode on. Wow.

To reach the elevation deck, we went outside for a moment. We could see the altitude bearings and motors. And now I understood where the counterweight was. I remarked that it seemed small. Brendan agreed and said he'd like to see more added. He verified my suspicion, that the telescope is nose-heavy.

We entered the "twister" room. Fantastic. I had wondered how things would connect in the junctions. We saw massive cables on three looms. The looms would elevate when more cable was needed. This allowed the turret to rotate more than 360°.

The next part of the tour felt like we were on a ship or a submarine. Das Boot scenes came to mind. Through oval portals, we entered the Vertex Cabin. Brendan said he had two modes for working in this space. Below us was the floor. Now. But if the dish was aimed to the horizon, the "wall" to my left became the floor. He said you had to be careful where you put tools... If you didn't secure them, they'd go missing.

He pointed out the Cassegrain funnel. In that configuration, the dish could be used for planetary work. The final leg. One after another, we climbed the ladder to the brightness above.

We were on the dish! Holy smokes. Amazing. I had hoped we could walk on it, like Sara had. Not a lot of telescopes you can walk, run, or sit on. Wow. Chris said, "We don't often get to bring people up here." I felt very privileged.

I looked through the rectangular holes in the plates. Looked over the edge, through the mesh. One must not have a fear of heights. I was fascinated by the fasteners for the plates. Decagonal or dodecagonal heads.

It was hot as we emerged. I already had my sunglasses on. Incredible. In full sunlight, it'd be a scorcher. They should recommend sunscreen too! Sunscreen everywhere. Don't forget the bottom parts too...

It was noted that the arms holding the focus cabin were asymmetrical. I surmised the "bottom" ones were designed to carry more weight.

We heard the wind in the mesh. The dish was singing to us.

Brendan pointed out the water drain. And with grey clouds broiling, asked us to be ready to exit immediately should it begin to rain. Also, the seals are going. If it rains they prefer to orient the dish so no water collects at all.

Katrina spotted a bull's eye reflective marker. It was from an old experiment. Chris said that you could see them coming up the road. Ah ha!

What a painting job.

The rain started. We exited back to the Vertex Room, down one more level, and then took the long central spiral stair case to the interpretative level. Returned the brain buckets and headed down a level and outside. It was raining harder. Right on cue, when Brendan emerged from the tower, they started slewing the dish. And down came the water!



Photos by Katrina Ince-Lum, Bill Longo, and Phil Chow.

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