Chile Journals: 5 January – 2 February 2015
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Nearly five years have passed since I last wrote a public journal during my time working on the Atacama Cosmology Telescope (ACT) in Chile, but I am still asked about it from time to time. And then within the past couple of weeks, several people enquired whether I would resume the practice this time around. Those (happy) few who follow my literary output with particular solicitude will recall that for my previous visit to ACT, I was content to summarise my stay with a brief web-log; this time around I feel more ambitious and consequently hope that I have retained some of the vigour of my youth so that what is now undertaken may be prudently carried out.
My journey to San Pedro de Atacama began propitiously. As I was waiting in the airport lounge in Toronto—Toronto rather than Vancouver, as I left directly from a Christmas sojourn with my family rather than returning to my home city—a cheer erupted from the nearest bar as Canada defeated Russia in the final game of the hockey world junior championship.
The rest of the voyage was smooth and my schedule was really ideal: a direct flight to Santiago with only two hours of layover before heading north to Calama. When I arrived in Calama I was pleasantly surprised that the new airport building is being used. The old one, though it used to do the job just fine, had become terribly small and pokey due to increased traffic.
The last couple of times I have come here it has been winter and dark by the time the transfer minivan hits the road: now, however, we are in the middle of summer and on daylight savings, and I very much enjoyed the hour-long ride from Calama to San Pedro de Atacama. Near Calama there are a few dozen wind turbines that have been installed within the last two years or so. I thought they made an elegant addition to the spare, desert landscape.
ACT recently moved residences, from a place about a twenty minute walk from the core of the village of San Pedro to a more isolated compound further away from town. My first impressions are quite favourable and I shall have to put up some pictures sometime in the next few days. I was greeted by Masao upon arrival, and then Alessandro, who is also a new arrival from Rome. Later in the evening, Tobias Marriage, who is here working on CLASS, arrived with some food from Tchuchis, our favourite roast-chicken vendor in town, and when Mark Devlin and Jon Ward came down from the mountain after a day's work, we all tucked in. It was a nice end to a long couple of days.
This morning at nine, Mark, Jon, Pato and I headed up to the telescope, while Masao and Alessandro went to get supplies in Calama. As we drove up there were white clouds all above the mountains, which is the very reason that we choose this time of year to make upgrades and repairs to our instruments. A phenomenon known as the ‘Bolivian winter’ brings moister air from, well, Bolivia, and this kind of atmosphere is not conducive to our observations.
On the other hand, this time of year is quite pleasant for human beings. At the site, it is kind of warm in the sun, but never hot: one is generally comfortable in a sweater. Of course, I had to contend with acclimatising, but I know what to expect by know and rested when I needed to.
Once there, Pato and Jon began working on the connexion between our shiny new air compressor and the focus of the telescope where the half-waveplates will be installed. Mark worked with them, and also kept a close eye on a cryogenic test he is doing to try and fix a problem in the heart of our camera's refrigerator.
As for myself, I began setting up a new piece of hardware we have for reading our encoders—the instruments that tell us which way our telescope is pointing. The old system has been serviceable, but there are reasons to desire an upgrade, so I am seeing if that is possible. Of course, I soon hit a snag when I discovered that the wiring for the cable connecting to the new hardware is different from the old hardware, so I had to sit down and make a patch cable to shift the wires around. But to my satisfaction, this did the trick and I was able to see one of the encoders using the new hardware. This is by no means the end of the story: there is a considerable amount of integration yet to be done, but at least the first step worked.
Toby and Pedro, of CLASS, dropped by later in the afternoon and I decided to go down with them rather than stay up until everyone else was ready to go down: it had already been a long first day.
Yesterday, Masao fixed the radiator on our white truck that had been out of commission, and so we went up in a three-truck convoy. Well, Alessandro and I fell a little behind as we stopped by the store on the way to get a bit of food. The white truck made it up quite happily, and we were well enough in time for Masao and Alessandro to go meet the diesel delivery truck. This latter filled the big tank which holds fuel for our generators.
Mark, Pato, Jon and Alessandro continued to work on air and also prepared our cryostat to receive the new detectors that will be arriving in a few days. As for myself, I continued learning how to use the new encoder readout system. It was a little slower going today, but I'm making progress. At this point I need a couple more pieces of hardware, which should be coming tonight, hand-carried by Ben, our anticipated newest arrival.
The mountain seemed busy today with hikers: on our way up, we passed a descending tour van. I wondered if they had conquered the mountain very early and were returning in triumph or whether they had succumbed to altitude sickness. Once at the site, I descried two other trucks parked further up the road from our telescope near the old sulphur mine. Neither of them approached our site (which is unfortunately sometimes a problem). But I did spot the CLASS team nearby scouting out their site with the construction company bosses as they prepare to pour the foundations for their telescopes.
After going to mass in town this evening, I took the truck to get some more diesel, but to my great consternation, couldn't remember how to get to the filling station, and had to return defeated. Thankfully Masao had procured some jerry cans earlier; and everything was made all right again by a very delicious pasta dish created by Alessandro.
Yesterday Ben and Patty arrived, so this morning we were eight altogether ascending the mountain. This made it quite cosy up at the site when we first arrived and piled into equipment room—there weren't even enough seats. But people quickly dispersed to work on various tasks and it didn't feel too crowded for the rest of the day.
Ben brought some more equipment that I started setting up today; principally a piece of hardware built at UBC. I installed it in the receiver cabin of the telescope, and then realised that I had made a minor mistake putting it together back in Vancouver, as one of the connectors was female instead of male. So I brought it back down and made the modification before re-installing. Not everything has been fully tested, but so far everything is purring along.
I spent the rest of the day coding—there is going to be a fair amount of programming to get this new equipment integrated into the experiment. As the afternoon progressed I realised I was getting slower and a headache started coming on: I obviously haven't fully acclimatised yet.
There is a small mountain bike at our residence, which I borrowed to ride the six or so kilometres into town this evening. Only when I started out did I realise how small it really is. I felt like a clown riding down the highway as my knees came up to the handlebars as I peddled. This awkwardness, together with a cross-wind that started turning into a head-wind, made the ride more difficult than it otherwise would have been. At any rate, I arrived on time for mass; there was some kind of youth group there with a guitar and singing, so the service went a bit longer than I was expecting.
After, I met Ben, Jon, Patti, Alessandro at Adobe, one of the venerable restaurants in town. It was a good dinner, and after, when we came back, the skies were clear and the moon had not risen and the heavens were glorious. Some of the others took one of the trucks to drive to an even darker locale, away from the couple of outdoor lights at our residence. I look forward to seeing if they get some good photographs.
The flurry of activity continues at the site. Masao, Pato and Alessandro headed up early to meet a truck from the nearby ALMA observatory which came to pick up the forklift we had borrowed. They also took some containers of dirty oil for proper disposal.
In the highbay, Mark, Ben and Jon were busy preparing the cryostat for the imminent arrival of our newest array of detectors. In particular, a number of lenses and filters need to be installed very carefully. There were some tense but focused moments as these were handled into place. Jon also got some of the electronics out the equipment room and brought them down to the highbay. (This is the building on site where we can work on the cryostat before putting it in the telescope.) He will be able to use these electronics to monitor the temperatures inside the cryostat when it is eventually closed up and cooled down.
I myself was a spectator to the highbay gymnastics. Naturally, I continued the installation of the readout system I am working on. At one point, I needed to make another cable and was reminded how long it actually takes to make one robustly: I spent a lot of time ensuring that all the connexions were as they should be, since it is a mission-critical cable. I also rediscovered a database tool I made many years ago for recording our cable pin-outs, and updated it accordingly. I has turned out to be quite handy—and in this era of rapidly evolving technology I was even a bit surprised that a web interface written probably eight years ago still works perfectly!
I came down at about six with Pato and Alessandro, while the others stayed up to finish up the day's work on the cryostat. Later in the evening, I asked Masao if he knew where we could purchase a bicycle—a larger one to complement our little one. It turns out that he was looking to sell his old bicycle: he had given it to the local bicycle shop to sell, but as it was still there he offered to sell it directly to us. So we hopped in one of the trucks and picked it up. He introduced me to the bicycle shop owner, who replaced the chain and tuned it up. He was a pleasant gentleman and told me to come back if there were any problems with it. The bike is of good quality and we are lucky to have acquired it.
To-day I stayed down in town and took much of the day off. In the morning I caught up on the sleep that I have been cheating on, and after a leisurely breakfast, helped Mark, who had gone up to the site with the others, get the telescope moving. We are moving it back and forth continuously right now as a test to ensure that it can operate without any of our computers freezing up on us.
The Sunday mass in town is at noon, and I debated whether or not to take the bicycle or not, seeing as the sun would be at its highest at that time. In the end Masao needed the truck, so circumstances made the decision for me. And before noon it was still cool enough that I was not in a complete sweat when I arrived. The new bicycle worked well.
The church building in the centre of town is a real landmark: it was built in the seventeenth century and has been declared a national historical monument. Currently, however, it is undergoing major restoration work and is only opened to the public for a few hours every week. Church services are temporarily being held in a hall across the square that is at most half the size of the church building; so today it was quite full, though I don't think there were many standing at the back.
There was snow on the mountain today—from below, it was completely obscured by clouds at various times. Thankfully, none of the snow stuck around: my colleagues reported that it immediately underwent sublimation when the sun came back out. Down here at 2,400 metres, it had become quite hot (but always very dry) by the time I arrived back from town, and then very windy late in afternoon.
This evening Patty and I cooked up a vegetable stir-fry with rice. She had the courage to put the whole ginger root I had purchased into the mix. This turned out to be an excellent move, giving the dish just the zing that it needed. Mark, Jon and Ben went to Tchuchis, the super chicken store, to supplement the veggies with some meat. It was a nice, convivial end to the day.
Today was one of those days that is productive but relatively uneventful. My own project progressed quite nicely. I was able to get the new equipment I have introduced synchronised to our existing systems: there is still a lot more to be done, but now one of the basic parts seems to be in place. It was all software today: no cable-making!
Meanwhile, in the high-bay much progress was made, and the cryostat is now ready for the detectors to be inserted. The large optics tube full of lenses and filters was carefully put in place, and everything was secured and fitted together.
And, in a stroke of perfect scheduling, Michael Niemack arrived this afternoon with the detector package. To-morrow it will be taken to an ALMA facility for some tests to make sure that nothing got damaged or loose during the journey, and hopefully soon thereafter it will be placed into the cryostat. It should be mentioned here that the fact that these detectors have arrived on time is due to some heroic efforts and serious overtime by many—including in a particular way some of our outstanding graduate students.
The mountains are to the east of the town, and this evening I was reminded how lovely they look when the sun sets, for when the town has gone into dusk, the mountains above are still lit up. Though bright in contrast to the darkening of your surroundings, the light from the setting sun is still soft upon the mountains. At the very end of the evening, the very tip of the dormant volcano Licancabur was glowing above the shadows beneath.
The day ended with Alessandro taking us on a tour of the night sky, as he is very knowledgeable about the constellations. The highlight was being able to spot the currently-visible Lovejoy comet—the first time I had ever seen a comet for myself.
Today we swelled to the maximum number of people—nine—that will be present here during my stay. I went up with Mark and Michael Niemack&mdas. The latter was a few years ahead of me in graduate school at Princeton, and it was good to catch up with him a bit. At one point driving up the highway we were stuck behind a truck carrying sulphuric acid—there are many of these going to the mines nearby—and were naturally more careful than usual in overtaking it.
I finished up much of what I can do on my project without having the rest of the equipment here: the actual half-waveplate mechanical system (which I'll certainly describe and post pictures once it is here). Currently the package is clearing customs in Santiago. This is often a frustrating and time-consuming process, but I have had word that it should be boarding a bus tomorrow to come the sixteen hundred kilometres to San Pedro. In the meantime, there are plenty of little projects to work on.
Once Mike had gotten up to speed at the site, he, Patty, Ben and Jon headed down and then over to ALMA to initiate testing of the detector array. I finished up some of my coding, and then briefly went out to help Mark, Alessandro, Pato and Masao attempt to repair a breach in our fence. We were somewhat successful: it will at least keep the curious out.
I came down with Mark at about three o'clock, in time for him to catch his shuttle bus to the airport, for he is returning to Philadelphia to resume his teaching duties. I spent the rest of the afternoon putting some touches on software, catching up on some correspondence and joining a teleconference for the other project I work on.
Currently in our kitchen some wonderful souls are making empanadas. The latter appear to be plentiful and I look forward to consuming a couple of them in the not too-distant future.
To-day with some of the others we visited the ALMA Operations Support Facility (OSF): a cluster of living quarters, offices and laboratories at 2,900 metres that services the observatory higher up in the mountains. It is an impressive complex that simply dwarfs ACT in terms of scale: scores of people work here at any given time; they have their own cafeteria, recreational facilities, and so on. We saw two of their twelve-metre dishes on-site being serviced—the rest of the over-sixty dishes are up at the 5,000 metre observatory about ten kilometres from ACT. The OSF itself is located about a twenty minute drive from our residence, in the middle of nowhere. We spoke to one of their scientists there, exchanging information, and shared a meal with him in their cafeteria that has a nice vista overlooking the desert.
The rest of the day was spent working on our newest detector array—i.e., one of our telescope's cameras. In the morning, I was recruited to help with this effort because of my computer trouble-shooting skills. We need to test thousands of connexions inside the detector array, and we do so by hooking a fancy multimeter up to a computer and automating this process. However, the interface between the multimeter and our computer had broken. I spent the morning trying to figure out it, and by dint of sheer stubborn perseverance got it working just as Ben, Patty and Mike finished their preparations of the detector array.
In the afternoon I was a fascinated spectator to the detector team's work. I had my own projects to work on, which occupied most of my time, but I popped in every now and then to see how things were going. I spent a year as a graduate student working on detectors, but have not had much direct contact with them since, so it is stimulating to see the fantastic work that has gone into this piece of machinery—literally several person-years.
It ended up being a long day: we didn't finish until about ten in the evening, but at the end of the day everyone was happy with the progress we made.
To-day the detectors arrived at ACT. Mike, Patty, Ben and Jon transported them by the less-bumpy ALMA but much longer road to our site; Alessandro and I went up the more direct route. However, we were slightly later than they because as we were setting out we realised that we only had a quarter tank of diesel in the truck. We had to stop by in town to put some more in, and there was a long line-up at the petrol station.
The detector crew is making good progress getting the array into the cryostat: the continuity checks of the wires went well, and soon they should be able to start closing everything up. I played my own little part by helping Jon do a couple of solder joints: tiny little wires to tiny little connectors. I think we got good bonds.
I spent most of the day improving the computer program the controls many aspects of the experiment, and was satisfied to get the upgrades done in the afternoon. Then I turned to something less glamorous and spent a good ninety minutes or so cleaning up our work space, which has become quite cluttered. I discovered that we have enough canned food at our telescope to survive for a few winters if needs be.
Alessandro and I left together when he had finished working on a constructing a baffle to block stray light from the focus of the telescope. On the drive down we saw a couple of interesting sights: first, some vicuña not too far from our truck. They were wild (there is no domestication of them at all, I believe) and not very shy of our vehicle, so we could watch them for a few minutes. Then, as we drove away, we spotted quite prominent sun dogs.
I made a second trip to the petrol station this evening, to fill up the same truck again (as I had only put in a quarter of a tank in the morning) and all our jerry cans—the latter save us from making trips for each of the vehicles. I left the station having purchased one hundred fifty litres of diesel for our vehicles. When I returned, I found that Alessandro had provided fuel of a different and much more tasty sort, and the six of us—for both Masao and Pato left this morning—sat down to spaghetti to end our day.
Over the past couple of days, I have been anticipating the imminent arrival of the half-waveplate shipment, which left the United States over a week ago. When it arrives there will be a new wave of work for me; in the meantime I decided to stay down at the compound and work on some odds and ends that needed my attention. This afternoon I found out that the shipment is actually expected Tuesday next week, due to a mix-up in the delivery from Santiago to San Pedro: apparently it was put on a slow bus that will take four days.
Meanwhile, Alessandro went to Calama to run some errands; in particular, he had to fill up the oxygen bottles that we use when we are at the site and not yet acclimatised. The other four went to the site to continue working towards closing the cryostat.
This morning I decided to take part of the time I would have spent commuting to the site and apply it to a bicycle tour of our local environs. The area is sparsely populated, but there are many dirt roads of various upkeep that criss-cross the terrain: because it is a flat desert with little vegetation, it is easy for tire tracks to consolodate into a makeshift road: these complement the properly constructed ones. At any rate, it was invigorating being out in the desert; I went as far as the edge of the large salt plain: eight or so more kilometres would have taken me to Laguna Cejar, one of the beautiful lakes filled with flamingos in the salt plains.
This evening we went out for dinner, to Blanco. It opened back in about 2008, and at the time I thought it seemed quite hipster for San Pedro; today, though, it seems to blend in more. At any rate, the food and the pisco sours were good.
Seeing as the shipment I await is still a few days away, I decided to try and jerry rig something together and make some progress on implementing our new encoder readout. In the end it ended up being one of those very frustrating days. I made some silly mistakes, and then when I had put it together properly I had difficulty understanding the signal levels. Altogether a discouraging day for me, but that is part of the terrain, I suppose.
Over in the highbay, things keep moving along—the same mantra I have been repeating every day for a while now. It is incredible how much work and attention to detail is required at each step along the way. At this point the detectors are being covered up in layers of metallic containers like Russian dolls which will eventually sit at different stages of refrigeration.
It was Alessandro's last day and he finished with panache, completing a very nice looking baffle at the focus of the telescope. It will prevent stray light—i.e., light not coming from the mirror but bouncing in from elsewhere—from entering into our camera and contaminating the signal.
It ended up being quite a long day. Patty, Ben and Jon left a bit earlier than the remaining three of us. What with cleaning up and putting away my tools, and then a forgotten passport at the site which we had to turn around and retrieve, it was dark by the time we started going down. Venus and Mercury have been close to each other these evenings, and they are by now a familiar pair rising in the east. We had our final evening of Alessandro's now-famous spaghetti when got down.
It was a nice, quiet day for me. I caught up on some sleep this morning, appearing just as the detector crew was heading up. Alessandro was around too this morning, as he departed in the early afternoon to return to Italy. I spent much of the rest of the morning addressing my piled-up correspondence.
I rode the bicycle into town again this week for the noon mass. There is a bicycle port at the museum right next to the church where I lock up; near the museum entrance is a UV strength indicator: a sequence of lights tells you how quickly you might get a sunburn, providing two columns: one for people with light and one for people with dark skin. It was at its maximum possible value.
I had some personal projects to work on in the afternoon, and then did some work on telescope software. In the evening I cooked up a casserole. The limited selection in the little grocery stores in town forces me to be a somewhat creative cook, but I was generally satisfied with the result. When the others arrived from the mountain they had picked up some beer and pizza and we watched the game to close out the evening.
Today the cryostat was closed up, and it is pumping out to a vacuum as I write. It is certainly a milestone, but it is not yet time to call the `all-clear': to-morrow we will have to check carefully for any leaks, as the vacuum needs to be, well, air-tight. Meanwhile, I spent most of my day trying to get the new encoder readout system working, making some progress, but not as much as I would have liked.
This evening when I was riding the bicycle into town there was a punishing headwind for the whole five or so kilometres. (I recalled my brother once saying that during his cross-Canada bicycle tour several years back, the hardest parts were not necessarily climbing the mountains, but riding into a constant wind.) At one point three motorcyclists rode beside me and were asking me something, but I couldn't hear them through the wind. Eventually I figured out that they wanted to know where San Pedro was. I could simply point, for we were right on its outskirts, and they speeded off ahead of me, slightly envious that they had motors.
A couple of days ago Spider, a balloon-borne telescope built by some present and former colleagues of mine, completed its flight in Antarctica. We all look forward to seeing what they get from their data!
When the others headed up this morning, I stayed down in anticipation of the arrival of our package. Later in the morning, I got confirmation that it had arrived, and drove into town to the Turbus office to pick it up. I didn't have high hopes that that would be the right location, but to my pleasant surprise, there were the five boxes were all ready to go. Of course, doing all the paper work took the typical amount of time, and it was after one by the time I was back at the compound, after having stopped at the petrol station to top up the truck and fill the empty jerry cans.
I headed up soon thereafter with the boxes. Jon opened them up and it looked like everything survived shipping intact, though the boxes were a little the worse for wear. Meanwhile, I continued my work with the encoder circuit, and was very pleased to get it working finally, thanks to some tips from some colleagues in the States. There's still a lot of work to be done, but I think the ‘proof of concept’ is in place.
Mike and Patty worked on leak-checking the cryostat. This is performed with an instrument that is very sensitive to helium gas. One sprays helium gas on all of the joints of the cryostat, and if there is a leak, helium will enter the cryostat and then be sucked out by the vacuum into the helium detector. In their first tests they were happy to report no leaks—though there will be more tests to come as the cryostat continues evacuating.
Late in the afternoon it began snowing at the site: a consequence of the Bolivian winter. We kept a close eye on it as it kept falling thickly, and decided to leave once it began accumulating in earnest. Two or three hundred metres lower, though, and we were out of the cloud and the roads were clear, all the way down to the compound.
It was a long but productive day to-day. The snow stopped overnight and there was no appreciable snow on the roads going up, except for a couple of foot-high drifts. But the aspect of the landscape was very different. The mountains were tipped in snow, and the flat was mottled brown and white. Towards ALMA there was a low mist which made the view from our site quite lovely.
After some more (successful) leak-checking, we opened up the highbay and prepared to move our nearly one-tonne cryostat over to the telescope. Ben had designed a very efficient method for the transportation. The cryostat was placed on a wheeled cart, which sits on rails. Two ten-foot long sections of rails are available, so while the cart is on one section, we could move the other one from behind to the front, and so continue the railway. We then tilted the telescope down to its lowest position, attached a ramp, and used a chain-hoist to pull it up the ramp. Finally, we tilted the telescope back up so that the cryostat was on a horizontal surface again. Needless to say, we took each of these steps carefully, as nobody wanted to be steamrollered by a one-tonne load.
Once inside the receiver cabin, we hoisted it roughly into place with some come-alongs, and then began assembling a sturdy aluminium structure—this included a couple of hours of tightening several dozen bolts, some in rather awkward to reach positions. Finally, the cryostat was secured to this structure. We put it back on a pump to keep improving the vacuum inside.
We will need to adjust the position of the cryostat eventually so that the cameras are at the focus of the telescope, but for now, the cryostat is securely in place, and we departed after after about eleven hours of work, all told. That being said, it was a good day for me. I enjoy working with my hands when I get the chance, and this day supplied that in abundance. My wrist is sore from so much spanner-work.
I drove down with Mike and Patty. Venus was setting above the most delicate sliver of a moon. Descending from altitude accelerated their setting, and when the moon was almost completely below the horizon, it left up one tiny little finger before disappearing.
After our long day yesterday, we allowed ourselves a bit more time in the morning, leaving for the site well after nine o'clock. Once there we found that the vacuum in the cryostat continues to improve. We will need to pump for a few more days still—not only is it a large volume, but there are a lot of surfaces with nooks and crannies where gas can stick, and it takes a while for all of this to be sucked away.
Right next to ACT is a smaller telescope for performing the Atacama B-Mode Search (ABS). It has finished its current run of observations, and this turned out to be convenient for ACT today, because we needed some electronics that ABS happened to have on-site. With kind permission from the ABS team, Patty and Mike carefully removed the parts that we need. This will save us much delay in getting observing with ACT, as we will not have to initiate a lengthy ordering process for more parts.
I spent most of my time at the site working on the newly-arrived equipment; in particular, adding to some of the electronics to enable the new encoder readout scheme. I didn't have time to test it properly before leaving, but hopefully to-morrow when I try installing it things will work out well.
Mike left soon after noon to go to the airport and return home. The four of us who remain left the site earlier than normal today, because an expedition to Calama—the nearest city—was in order. Most pressingly, Jon needs some tubing for the half-waveplate air system which he hoped to find at one of the large hardware stores in town. I remained behind to get some work done down in our office, and had a good, quite evening.
The highway from the mountain, which runs roughly east-west, comes to a T on the edge of San Pedro with a north-south highway; we are about five kilometres south on this latter highway. There is a diagonal road that cuts the corner considerably, but at a cost: about a third of the way along, there is a massive hole in the middle of the road, with absolutely no signs or warnings. We generally avoid it for fear of forgetting about this devastating obstacle. Today, though, having the benefit broad daylight, we took it so that I could view the spectacle. The hole was much deeper than I had imagined.
This morning we met a new friend when we arrived at the site. There was a fox on the road not a hundred metres from the telescope. I have seen foxes on the drive a couple of times before, but never this high up. While he was cautious, he certainly wasn't frightened of our vehicles or us, and we were within twenty metres or so.
There were construction workers for CLASS around this morning, and I chatted with them for a few minutes. They said that they had seen foxes in other places in the altiplano, presumably near to ALMA. And they confirmed that it didn't have a name.
I worked on installing some equipment in the receiver cabin of the telescope, helping Jon get some instrumentation in place, and then ensuring that the circuit I introduced into his box yesterday worked well; I had to make yet another cable. I had a bit of scare when I thought that one of our position encoders had broken, but it turned out to be fine. The others worked on getting things plugged into the cryostat and generally preparing to switch on the refrigeration, although it still needs to pump out to a higher vacuum.
When I went to get the bicycle to ride into town I found that the back wheel was completely flat, with a sizeable gash on the outer tyre by the leak. I'm not sure how it came about, but it must have happened right as I arrived home the previous evening because the tyre would have gone flat very fast. At any rate, Alessandro purchased a patch kit when he was in Calama a week ago and the repair on the inner tube is currently curing.
The days recently have been very fine, after the snow we had a few days ago, and it is very pleasant driving up to the mountain. Once there, one can almost be in a t-shirt outside, but is borderline.
The cryostat continues to pump down and is making good progress. Ben and Patty kept an eye on it and were in communication with North America about when would be good to start cooling it down. (We think Monday.) Jon worked on installing the half-waveplate mount on the front of the cryostat. We had to nudge the latter back and forth a bit so that he could access all the screw holes: this ended up being more effort than anticipated, but worked out in the end.
And the hard work paid off: Jon successfully spun up half-waveplate mounts on their air bearings, and it was a thing of beauty to watch them keep spinning and spinning after just a gentle push. He will install the actual motors later, but to finish the day he hooked up the readout equipment and we verified that we could see the encoders through the whole hardware and software pipeline.
When we came down I found that the bicycle tyre I had attempted to repair was deflated. There was another large gash that must have opened up when I reinflated it, and this one was too large to repair. So I installed a new inner tube in the tyre and took the bicycle out for a quick test-run through the desert across the road. A few minutes later, I realised that one of the three dogs from our compound was accompanying me. He was positively delighted to be out and bounded all around me as I rode over the hardened sand. I was only away for fifteen minutes or so but it was quite enjoyable.
After mass this evening—at which two young girls were baptised—I made the mistake of going to the petrol station to fill up the truck. I did not have to wait long to get a pump, but exiting the station was absolutely chaotic. The lane-way is quite narrow, and a bus was trying to turn the corner unsuccessfully. It kept backing up, and I kept backing up, until I signalled to ask if I could pass. There was barely any room: I had to close the passenger side mirror to get by, and then when I had escaped there was a long line of cars on the street all trying to turn into the station. The road was narrow, so it took a long time for me to crawl down the street, and even then I met several more vehicles. Saturday night in San Pedro has become busy.
Today we took a much-needed day off. I made pancakes for breakfast, and after a leisurely morning we headed south, past Toconao, through Socaire, and to our destination: the Miscanti and Miñisque lagoons. These shallow lakes at over four thousand metres are beautifully set in a small but gently-sloped valley. Because of the sensitive ecology, visitors are not allowed to approach the shores, but the visit is still very worthwhile.
On the way there, we stopped at the Tropic of Capricorn. A sort of tube sticking out of the ground marks its location, which is also, apparently, on part of the Inca Trail.
The Miscanti and Miñisque lagunas are in the National Flamingo Reserve, but we did not see any of the titular birds there, so on the way back we stopped at Laguna Chaxas. I and Ben had been there a couple of times before, but it is always a nice place to visit and there were plenty of flamingos.
We returned to the compound late in the afternoon and relaxed in the evening, recharging to return to work to-morrow.
Jon and I continued installing the half-waveplate hardware and software, making decent progress. The motors are now installed and spin the mounts nicely; though those of you have been following this journal attentively will not be surprised that cable-making will continue.
Meanwhile, Patty completed another successful leak-check, and then Ben started turning on the refrigeration for the cryostat, with help and advice from North America. It will take many days to cool down even with several kilowatts of refrigeration, because it is such a large mass, but if all goes well, the detectors will eventually be colder than outer space.
Ben and Patty went down mid-afternoon while Jon and I kept working above. At one point Ben called and said that the mountain looked pretty cloudy; to us at the site, though, the weather, while not sunny, seemed unthreatening. But when we finally left, we saw that a few hundred metres lower the clouds were dark and thick, and then by the highway, we entered the rain.
This is the first trip I have ever seen rain in San Pedro. Yesterday we got a few drops, but this afternoon, it was a veritable downpour. It was raining hard with humongous drops as Jon and I drove down; when we reached the lowlands the rain was accompanied by blowing sand in the high winds which reduced but did not eliminate visibility. Back at the compound, it was still raining, with strong gusts of wind. That particular odour of wet dust was everywhere; for a couple of hours, at least, one got mud on one's shoes rather than kicking up clouds of dust. But by early evening it was finished, and things are already drying up.
It was a long but productive day at the site today. Jon, Patty and I went up in the morning, while Ben stayed below to get some work down in the low-altitude office. Up at the site, Patty did some heroic clean-up, and then turned her attention to installing software for testing the arrays on one of our laptops.
Jon and I concentrated on continuing the half-waveplate installation, with Jon focussing on the hardware and I on the software, more or less. He made sure all the connexions where robust and well-secured—a task whose amount of work is often underestimated and sometimes under-appreciated—and programmed the motor speeds in. At their fastest, they complete two revolutions per second. This creates a good software puzzle because we want to know where it is in its revolution to good precision over four hundred times per second. Solving this puzzle is now my main task
Meanwhile, Rolando flew in this morning to work on aligning the cryostat so that our cameras are at the focus of the telescope. He has a special digital camera and computer software that can determine the three-dimensional positions of objects by comparing pictures taken at different angles—a technique called photogrammetry. He and Ben came up in the evening to start working on it: in the evening because the photogrammetry works best in the dark when the camera flash can provide high contrast.
As they needed more than two people for this task, the three of us who were up waited for them to arrive. Ben and Rolando kindly bought us some sandwiches to sate our hunger. Unfortunately, it had started lightly snowing by the time they arrived, which meant that they could not make measurements in earnest but could only do some preparatory work before we all headed down.
Jon and I headed up in the morning to continue work on the half-waveplate system. There is not much to report on that front: it was an uneventful day as far as this journal is concerned, but eventful in terms of making progress. Perhaps most of note for the wider world was that I discovered some pretty good beans for lunch at the site that mixed well with tuna.
I worked another long day, and therefore elected to be down in the evening while the others are up working on measuring the cryostat position. The weather was fine during daylight, but as dusk approached the clouds started rolling in. Nevertheless, the snow stayed at bay, so the photogrammetry is proceeding, and hopefully it will be a productive night, especially as Rolando can only be here for three evenings.
The measurement crew was busy last night well into the morning—with good success, I was told—and so they slept in late this morning, during which I worked in our low-altitude office.
After noon, Rolando had to pick up a local archaeologist to do an assessment of the CLASS site (a project he is also involved with). Patty, Jon and I went along to go up with them. The archaeologist is from the Atacama and his big project these days is restoring the church in San Pedro, which dates from the seventeenth century. As we drove up, he told us interesting things about the history of the region as we were driving up. At the CLASS construction site, he ensured that they would not interfere with any cultural remains, or, more importantly, any human remains, since the ancient peoples here did frequent the high altitude sites.
I spent much of the afternoon cleaning up the morass of cables in the computer rack in our control room. After a few years of cables being plugged and unplugged, a loose but sizeable knot had developed that I needed to untie to get some new equipment installed. As usual, the task took longer than anticipated and I will have to finish to-morrow.
Meanwhile, Jon made some adjustments to the half-waveplate mounts, after which, having descended, I was able to read out the rotation position for the first time through the whole system. More work is still to be done to fine-tune it, but it is a milestone.
This evening, thanks to Jon, I found that we had some gnocchi in the kitchen. It was a great end to the day—for Jon and me, at least, for the others have returned to the site to continue with the cryostat positioning.
This morning Patty and Rolando left early in the morning. Ben drove them to the airport as he had to pick up a package and buy a couple of things in Calama. Jon and I went up to the site, where I finished cleaning up the cabling and left it in a much more manageable state. Afterwards, with Jon's help I got the remote control of the half-waveplate motors working, so that we can turn them on and off and change their speed without being physically present.
We also had to switch the generators today. There are two at the site, and we alternate between them every couple of weeks so that the one that is ‘resting’ can have its oil changed and be serviced if necessary. Even though one doesn't immediately think of taking care of generators as a part of astronomy research, they are really essential to our project. Without them, obviously, everything shuts down.
It was raining again on the descent, but this time the precipitation was confined to the mountains, and it was dry back at the compound.
We went out for dinner tonight, to Adobe again—for me a welcome time to relax after a long and busy week.
Yesterday when we left the site I thought I had left everything in order so that I could continue remotely today. But when I began working this morning I found that I was not able to read the new encoder system I have been working on, and suspected that I had forgotten to plug in one of the cables—or worse, that something had broken in the electronic chain.
Jon agreed to come up with me in the early afternoon to see what was awry; when we arrived, I found everything connected as it should be, and after a bit of investigation I discovered that it was in fact a subtle software bug: the trip was unnecessary after all. But at least we were able to do the generator checklist; back down in town I made some good progress despite the lost time.
Late in the afternoon it became very windy and, for a few minutes, there was quite a dust storm. We thought it might rain again, but after half an hour or so it just blew over. When I came back from mass in town just before nine, it had cleared up. Jon had very kindly picked up some empanadas for supper.
I learnt this morning that there are some roads one cycles on at one's peril. Taking the bike out this morning along the highway, I spied a side road that went through a grove of trees and decided to see where it led. Less than a kilometre down, I heard a heart-sinking hissing noise coming from my front tyre, and then realised that the grove was populated with thorn trees. Thankfully, I was only about three kilometres from the compound, so I locked the bike to a tree, walked back, and then came back with the truck to pick up the bike. Later in the afternoon, I took out the inner tube to patch it up, but discovered that there were more than a few punctures. Perhaps we simply need thicker tyres—or we should be careful which roads we follow.
It was a generally tranquil day; I tied up some odds and ends. But of course it was also Super Bowl Sunday, and as the evening approached we prepared snacks and a barbecue as per the tradition in the northern parts of the Americas. Masao had just arrived back from Santiago, and the manager of our compound invited a few friends over to join us. As the meat was coming off the grill we moved the television outside and enjoyed the game. Our Chilean friends watched a surprisingly large fraction of the game, but left for another (non-Super Bowl) gathering at the beginning of the last quarter. We were left to contemplate why the Sea Hawks opted for a passing play during their last possession as we put things back in order and headed for bed.
Today I left San Pedro. In the morning I packed up, tied up as many loose ends as I could, gave a hasty core-dump of the current state of the software to Jon, and hopped onto my shuttle transfer to the airport which arrived at around one. It was a good stay—hectic at times, but over all enjoyable and productive, as far as I can see. I leave behind Ben and Jon, who are around for just over another week, and Masao, for a few.
When I arrived at the airport I discovered that my flight was delayed two hours, but was assured that my connexion in Santiago would work out. Of course, airlines are no exception when it comes to over-optimistic estimates of delays, and when I arrived in Santiago, my flight to Toronto had been closed. So I shall stay in this country for another twenty-four hours: not necessarily a bad thing, since it is summer here and the airline has put me up in a rather comfortable hotel where there was a very succulent fish for supper.
In the past, I have continued this journal until arriving back home in North America. But tonight I think it best to end here: after all, chronicling another day of air travel, while potentially fascinating to some, is probably not the most riveting material for the majority of my audience. And so: adieu.