Holding my breath

Bear with me - this is a long and technical update. But if you've been wondering what's been keeping me busy or why I'm here, here's more information than you ever wanted!

Normally, the work that I do for the SPT involves lots of programming. My main job is to put together the software tools that we need to look at the raw data from the telescope and process it into images that we can use to learn something about the evolution of the universe. A huge part of analyzing this sort of data is trying to understand as much as possible about the behavior of the telescope and the characteristics of the detectors that we use to observe light from the early universe. The measurements we are trying to make are exceptionally sensitive, and if the telescope isn't pointed exactly where we think it is, or if we don't fully
understand how the detectors respond to the radiation that they absorb, we can't interpret the raw signals that are recorded while we're observing the sky.

To me, the challenge of fully characterizing an instrument and all of the possible sources of uncertainty in a measurement is the most interesting part of experimental physics. Even though I work with this sort of stuff every day, I still think it seems crazy that we can claim to make valid, robust statements about something as grandiose or remote as the dawn of the universe or the evolution of its major components. What I find most inspiring and profound about experimental work is the careful and detailed arguments that experimentalists must make to justify and defend every statement that they make, in order to build up robust arguments backing up each claim. I personally want to be able to stand behind our measurements, to defend the correctness of our inferences, and to feel that I could explain every cross-check and every step in the argument that takes us from measurements of voltages in our detector readout to saying something about the entire universe. That's a tall order! But to me, it's the most interesting challenge and what motivates me.

Both because this whole facet of experimental work fascinates me, and also because I was available to spend the whole season at the pole this year, I got involved in some calibration measurements that we need to perform in order to understand our optics and response to light of different frequencies. Before we can interpret the signals that we recorded during our last season of observing, we need to know how sensitive the whole system is to microwave light of different wavelengths or frequencies. Like our eyes, the telescope is sensitive to a range of different frequencies of light. For our eyes, different frequencies manifest as different colors. Our eyes are most sensitive to colors that are yellow, and fall off in sensitivity at the low frequency end of the visible spectrum (the infrared) as well as the high frequency end (the ultraviolet). Similarly, we want to know which microwave frequencies our detectors see best, accounting for their own response as well as how the different parts of the optical system affect the light that they see.

To make this measurement, we take a radiating source (basically just a really hot object that emits a lot of light across a broad spectrum), and we send the light from that source through an optical device called a Fourier Transform Spectrometer (FTS). The FTS bounces the light through two paths and recombines it, then sends it through the window of our "optics cryostat", where it bounces off a big mirror and finally hits the detectors, which are held at a temperature just barely above absolute zero inside the "receiver cryostat". When we look at the signal that the detectors receive as we vary the path of the light through the FTS, we are able to probe how the whole system responds to light of different frequencies.

The FTS that we are using consists of an assembly of mirrors and fine wire grids mounted in a big metal box along with the radiation source. We had very little time to build this device before we came down, so we contracted with a company to build one for us. However, there were some shipping delays and I never got to see the thing before flying down here to meet it. We didn't even know for sure that all of the parts would fit together or that we would be able to mount it onto the optics cryostat where it could send light in towards the detectors, much less perform meaningful measurements with it.

So, when it finally arrived here, you can imagine how nervous I was to unpack the thing and see how it worked. Professor Steve Meyer back at Chicago designed many of the parts of the whole system, and he did a great job. It took a bit of problem solving to figure out how to put the thing together and get it mounted, but we were able to do so in just a couple of very busy days, with no major snags. Below is a picture of me mounting one of the mirrors into the box (which has its walls removed to make this easier). The picture was taken by Jeff McMahon.



Altogether, the FTS weighs a couple hundred pounds. So once we had the major pieces together, five of us VERY carefully lifted it and bolted it to the optics cryostat. The optics cryostat is the big white thing in the picture below. At the top of it, you can see part of a white circular window that is how microwave radiation enters the cryostat (the foam of the window is transparent to microwaves, but not to visible light). The red box that you see is the receiver cryostat. Inside that are all of the detectors. During normal operation, the two cryostats are hoisted up into the boom of the telescope and aimed so that the window faces the 10-meter dish of the telescope. In this configuration, we will mount some lenses to take the output of the FTS box and direct it into the window instead of pointing the window at the telescope mirror and out to the sky.



Below is another picture of the two cryostats, from the other side, so you can get a better sense of the size of these things. They're quite large, and the space in our control room is quite tight. A huge part of our efforts is keeping everything inside these cryostats very cold. Everything inside the big white cryostat is held at around ten degrees above absolute zero, while the detectors inside the red cryostat are held at a quarter of a degree above absolute zero. Only when we achieve these tiny temperatures can we actually use the detectors to make any kind of measurements.



The last step in the whole process of getting this thing ready, once we had the FTS mounted and the detectors cold, was to remove the metal plates protecting the fine wire mesh grids that are part of the optics of the FTS. These wire grids are made of tiny, fine wires stretched between two rings. The wires are so fine you can barely see them. They are so delicate you don't want to even breath on them, so the operation of getting in there with a wrench and removing those plates without damaging them was nothing short of petrifying. I think I held my breath the whole time, and I was sweating and shaking by the time I had all six plates removed. It's hard to photograph something this shiny, but you can see the wire grids in the photograph below - they look slightly gold-colored.



The last big question was whether we could turn on the radiation source and run the FTS and see it with the detectors. Two nights ago, we had a tiny window of time to try this, and graduate student Ryan Keisler and I stayed late out at the telescope to give it a first shot. With two laptops, we sat down on the floor and pulled up some plots showing us the data streaming live from one of the detectors. We moved the FTS around until the light from it was pointing right at that detector, then we ran the FTS. Amazingly, it produced a beautiful series of wiggles that told us immediately that everything was working. I just spent the last day looking at this data, and it looks great. I think we'll be able to get the calibrations that we need over the next week, and then move on to the next tasks for the season.

Right after we saw the first data from the FTS, Ryan and I shut down the laptops and raced back to the station to catch the rest of a science lecture being given by John Carlstrom, the head of the SPT project. The audience filled the galley and included all sorts of people from the station - janitors, cooks, carpenters, technicians... It was such an incredible feeling to walk in, breathless from the cold, and see this diverse and unique audience glued to John's descriptions of the telescope project and the science we are trying to do.



I didn't realize until we saw those beautiful little wiggles race across the computer screen that night that I had, in some sense, been holding my breath since arriving, not sure whether we would be able to pull this off. It's rare that you put together a brand new instrument and everything works the first time. So, now, I'm taking a huge deep breath and feeling a lot of relief...as well as excitement for the chance to get a better understanding of this incredible telescope.

Busy days on the ice

I've been at the pole for about a week now, and I not only settled in but extremely busy. My first task here is to perform some essential calibrations of the telescope, using an instrument that just arrived a couple of days ago on one of the flights. Each day I walk back and forth to the telescope several times, since the meals are all served back at the station. It's a 15 or 20 minute walk across the ice each way. Despite the fact that the landscape is utterly flat and featureless except for the station buildings, it is still so unique and so fascinating. Every day the features in the snow are different, and in the sunny weather we've had lately, the landscape is luminous and full of sparkle.

Made it!

If you've read my older blog entries, you might remember that I almost missed the flight from McMurdo to Pole last January, and I was the last one to report for transport. Well, I did it again. I took a nap in the afternoon, and during my nap the flight time got moved earlier than what had been most recently posted. I woke up all of five minutes before I was supposed to report. When I saw the latest updates on the screen, I threw all of my stuff together and ran up the hill to catch my ride down to the ice runway. The weather was beautiful and the trip this time was mercifully smooth. I spent almost the whole flight glued to the windows in the back of the plane. The flight over Antarctica offers a rare and exceptionally beautiful view. For most of the flight, we fly over the Transantarctic mountains. They are sizeable peaks, but they are drowned in ice up to two miles thick. Only the tiniest tips of the mountains peak out above the white. The view is unearthly, stunning, and mesmerizing. As we get closer to pole, the ice overwhelms the mountains and all that is left is a solid, featureless white plateau that shines in the sun. I enjoy this part of the trip so much... which I think you can tell from the picture at the bottom.









When we got to pole, the pilot came in to land, and then when we were just a few feet above the ground, took the plane back up again. I suddenly worried that we were being boomeranged again, or that something was wrong with the landing gear. But no, they just like to check out the skiway from the air if it hasn't been used in a little while. So we came right back and made a smooth landing, dumping cargo out the back of the plane as we slid down the skiway. I even saw a glimpse of the telescope through the window as we arrived, and I felt a rush of excitement.

I once again tried to snap a photo just moments after stepping onto the polar ice. It is hard to do while bundled up and with the shock of the cold and the need to quickly get away from the aircraft. The station was almost obscured by a huge pile of snow, the first pile of drifts that have been shoveled and cleared from the upwind side. As we were arriving, a large company of outgoing winterovers were gathered to immediately take off in the same plane. One of the two SPT winterovers, Zak Staniszewski, was on this flight, so I stayed to see him off. The picture below shows a shot of him and Steve Padin, our second winterover, at the end of their long eight months of operating the telescope. I could tell that it was a very emotional moment for all of the winterovers finally leaving the station. I only hope that Zak makes it to Christchurch soon to see his girlfriend and take a long, very well earned vacation.

All in the name of science

It is sometimes amazing to think that the massive infrastructure of the United States Antarctic Program is all here for the purpose of supporting science. At the South Pole, the biggest science projects are in astrophysics and cosmology, using the site as a unique observatory for probing the physics of the universe. Here at McMurdo, most of the science is concerned with the natural world closer to home: geophysics, biology, environmental science, and other disciplines about which I know very little. For the last week while stationed in MacTown (as it's affectionately called), I've been working from my laptop in the library/lounge at Crary Lab, the main science facility. The library has a spectacular view across the ice and is a really comfortable place for working (...as well as obsessively monitoring the activity on the ice runway outside, trying to tell whether they're preparing for us to fly anytime soon).

Spending time in Crary has also given me a glimpse into some of the many science projects taking place in this region of the continent. Downstairs, for example, there is a live feed from a camera at the opening of the volcano, Mount Erebus, that sits right above McMurdo. In the image, you can see the sloshing of the lava lake and the occasional explosions that jettison material out onto the icy upper slopes. Apparently, the lava lake is a relatively rare feature and the whole volcano is under constant active study by local scientists. They seem quite adventurous to me, heading out by helicopter to take trips to the volcano's peak. In the same part of the building, there are also scientists from the Andrill project, who are drilling deep into the sediments beneath the ice in order to study Antarctica's geological history.

You can't help but be totally captivated by the biological research taking place here, be it about penguins, seals, or critters from the bottom of the coldest sea. A few nights ago there was a public science lecture in the galley about the Wedell seals, and the audience was huge. There is something wonderful about seeing the enthusiasm everyone has here for the science that depends so much on their efforts to keep the station running.

One of my favorite memories from this trip will be visiting the Crary aquarium, which houses fish and other sea critters for study. They keep a "touch tank" filled with bright and bizarre animals that can be viewed up close, from your own hand. Two of the more colorful residents of the tank are shown below.



Finally, I have had another interesting encounter here with science that is far from my own field. A group from the Mayo clinic is performing a study on the physiological effects of high altitute. The South Pole is one of the few places where people regularly make trips to high altitude (it is physiologically equivalent to about 11,000 feet) without decending soon afterwards. So, as the polies come through McMurdo, the Mayo researches have been setting us up to do before-and-after studies. I signed up to participate in the study, which involved having 10 vials of blood taken (!) and a bunch of tests done to characterize my breathing. I also agreed to wear the "life shirt" while sleeping one night. Each of these tests will be repeated at pole, to see how the altitude has affected my body. The sleep studies are particularly interesting, since the high altitude is notoriously disruptive. With all of these wires attached to my body, I looked like a bizarre critter myself. But at least if I'm not able to be at the telescope working on my own science, I might as well help with someone else's.

It's Wednesday night here at McMurdo (we are a day ahead of the U.S.) and we just had yet another flight to pole cancelled. We were all packed up and out at the ice runway again and the weather turned blustery, the air becoming opaque with ice. You can't help but laugh about it though. When we all came wandering back into building 155 again, everyone else in the station certainly had a good chuckle. Nothing you can do about the weather. By now I think I've stripped my bed here four times and it was routine to come back in and go make it up again.

It's not all just waiting. We're managing to have a good time here too. A couple of nights ago there was an 80s dance party in one of the McMurdo bars. A bunch of people came over from Scott Base dressed in amazing costumes, with mohawk wigs and goofy sunglasses and the rest. Being stuck here without any of my luggage (it's all strapped into a pallet ready to fly at any moment), I did my dancing ever so stylishly in my USAP-issued insulated Carhartt coveralls.

After the party, my colleague Martin and I walked down to Hut Point at around midnight. This was the site where we saw penguins last year and where I was mesmerized watching the ice breaker working all through the night. This time, the bay was still covered completely in ice and the wind was blistering, so we couldn't linger for very long. On the way out, I was struck by the image of footprints in the snow, accumulating the raw volcanic dust of the surrounding landscape. Where each footstep falls, the snow compresses. When the wind blows, the snow between the prints flies away, but the compressed imprints of each bootstep stay solid, accumulating little snow drifts and eventually crumbling apart. The same thing happens in the ice at pole, and I've noticed it often on the path out to the telescope. There is something strange and haunting about seeing raised footprints withstanding the extreme winds, while everything else about the landscape drifts and changes so easily.



And once again, I took a moment (in a -45 degree windchill, it really was just a moment) to appreciate the midnight sun over the mountains. Just stunning. Even if all of the waiting at McMurdo can be frustrating, there is nothing like this view anywhere else.

Hurry up and wait

We've been stuck here in McMurdo for a few days. The typical trip to pole involves spending a night here, but if weather is bad in either location you can find yourself stranded here for days or even weeks. Right now, weather is bad in both places.



McMurdo has a large population during the summer season, housing more than a thousand people in a handful of dormatories on the side of a hill. Transients -- those bound for pole or various field camps -- are typically housed in the central building, building 155. This is also the building with the dining facilities, computer room, store, and various other services, all located along a central hallway called "Highway One". The picture above shows the front entrance to 155, and you can see some of the ubiquitous sorted waste containers out front. There are literally dozens of catagories of garbage here, since everything gets shipped back to the U.S. for recycling or disposal. Carefully sorting any trash you generate is a fixture of life here, as is obsessively washing your hands to avoid getting sick or spreading any illness in these close quarters. There are handwashing stations right inside the doors of 155, and there are signs everywhere urging good hygiene practices to keep everyone healthy.



Since we've been here, we have been on almost constant alert for flights to pole. Each day, we wake up early to meet our original departure time, but then the time slides later and later in the day as the weather continues to be prohibitive on one end or the other. Flight manifests are posted along Highway One and television screens give us regular updates on the weather and the flight schedules. A lot of our time in the last couple of days has been spent standing in the hallway watching these screens and trading rumors we've heard about the weather conditions and our odds of flying anytime soon.



On Monday, we actually made it into a plane and halfway to pole, but conditions at pole deteriorated and we had to turn back. By the time we had flown back to McMurdo, conditions here were extremely windy. Two other planes that had also "boomeranged" were forced to divert to the nearby Italian station, Terra Nova. Our pilot was determined to land us, and took us through three bumpy failed approaches before finally landing us safely. The turbulence during the failed approaches was intense enough to make quite a few people sick, and even once we were back on the ground I felt wobbly and disoriented for a while. It was shocking to see what the conditions really were on the ground -- it was so blustery that I found myself sliding across the ice if I stood still. I took a shot of the plane through the window as we rode Ivan back to the station, glad to be back on the ground for a little while.

Back to the ice

Who's getting the big hug? Actually, it's a dummy at the Antarctic Center museum. On the morning of our flight to Antarctica, we arrive early and put on all of our Extreme Cold Weather (ECW) gear prior to the flight. We then have a little break to get some breakfast or write a few last emails before we leave. The terminal is located just a few steps from the Antarctic Center, which is a local tourist attraction. The dummies in the picture are dressed up in their own ECW gear, but it's much more fun for the tourists to see a bunch of actual Antarctic workers and scientists gather for the flight down. Especially if the weather is warm in Christchurch, we look pretty silly in our giant red parkas and heavy white boots. Silly or not, the process gets you geared up for cold weather and also, for me, jumpstarts my sense of excitement.

The flight to McMurdo base takes about five hours, on a military C17 cargo plane. The last time I took this trip, the plane was fitted with many rows of seats to accomodate large numbers of passengers to the ice. This time, we numbered few enough that the seats along the wall were sufficient and all of the interior space was used for cargo. The picture below is just at the moment of lift-off, headed to the ice. Most of the people in the shot are new to the USAP and they are all doing a good job of looking cool, even though they are starting on such an unusual trip.



Because it's early in the season, we landed on the ice runway at McMurdo. There are three runways usually used, and I have now been through all of them. This one is constructed right out on the sea ice in the bay. Last year, I came through later in the season when this very ice was being broken apart to make way for the massive supply ship that makes an annual visit. Below you can see the C17 after landing. You can also see a group of Kiwis bound for the New Zealand station, Scott Base. All of their clothing and gear is in soft colors of blue and green, while the US participants are always somewhat jarring in our bright reds and oranges.



A short walk from the airplane, "Ivan the Terra Bus" awaits us, to give us a ride back to "town". The last picture below is a shot that I took out of Ivan's window. The sky was absolutely beautiful and I was once again overwhelmed by the experience of being on the ice.

Local Color

Christchurch is a welcoming place to come to on the way in or out of Antarctica. The Antarctic program seems to permeate everything. A tour bus topped with penguin statues makes the rounds regularly through town. Hotels and restaurants are decorated with photographs from Antarctic voyages of the past and present. And you can't walk very far in town without running into someone coming from or going to the ice. Within my first hours in town, I had already encountered several winterovers on their way back from a long dark eight months at the South Pole. Although they seemed well, each had a certain delirious and overwhelmed sense about them -- thrown back into the real world and not quite sure how to adjust to it once again.

For my first night in town, I went back to the Dux, the pub where Antarctic program participants seem to collect daily during the travel seasons. In addition to catching up with a couple of people I hadn't seen since last season, I also met many more. I spent most of the evening trying to explain the expansion of the universe to a handful of heavy equipment operators destined for McMurdo station. One of the best things about this whole program is how it brings together an assortment of colorful, interesting personalities, and people who wouldn't necessarily intersect with each other in their normal lives. I have a lot of fun listening to all of the personal stories, and it's also great how curious everyone is to hear about the SPT and the science that we're doing.

Seeing the returning winterovers did make me more aware, though, of just how far away I was about to go. For my last day in Christchurch, I made sure to soak in as much as I could of the sights, smells, sounds, and tastes of a city in the springtime. I ate lots of spicy food filled with fresh vegetables and cheese, enjoyed the bustle of the busiest streets, and absorbing the spectacular botanic garden. For more than three months, the colors of my natural landscape will be blue, white, and grey, with just a touch of gold from the sun. I spent an especially long time lingering in the botanic gardens just drinking in the colors and smells. I'm hoping that these photographs on my laptop will give me a quick, bright break from the everyday while I'm working at pole this season.