The Clock is Ticking

I looked up at the weather screen today and saw that the temperature had dropped to -38 F (which is actually almost exactly equal to -38 degrees C). The windchill today is about -60F. The dropping temperatures signal that the end of the season is rapidly approaching. Soon, it will be too cold for planes to land here, and the station will be isolated for a period of 8 months. Most of the SPT team is scheduled to leave on one of the last two flights out, expected to be on February 14 or thereabouts. As the end of the summer season approaches, personel on station are changing over as the summer staff leaves and the winter staff arrives. Rumors are flying about the station closing early, and about whether enough food and fuel have been delivered to sustain the station over the long winter. I think those rumors are as much a part of this season as the daily drops in temperature.

For SPT, this is a tense few weeks. We have just installed a brand new set of detectors in the receiver. These are much more sensitive than the ones that we used last season, but every new batch of detectors made at Berkeley is different, and it takes a lot of work to understand their features. We have a very short time to get the new receiver working, characterize the detectors, put everything in the telescope back together again, and get it all to work together. In the midst of this, we have two new members of the collaboration (Keith Vanderlinde and Dana Hrubes) who will be operating the instrument over the winter. They both need to be trained, and are understandably anxious about learning enough in such a short time to handle everything that could go wrong once the rest of us leave. I am not personally involved in much of the receiver work, but the tension permeates everything that we are currently doing.

Below is a picture showing a set of detectors like those we have just installed. Each little circular element is a few millimeters across, and is an ultra-sensitive radiation detector. The full array that makes up our focal plane consists of hundreds of these.



The detectors are fabricated on wedge-shaped wafers and then carefully installed in a 'wedding cake' assembly with optical feeds above each detector and a triangular filter above each wedge. The filters ensure that the radiation that reaches the detectors is the right frequency. The process of assembling and installing the focal plane is one of the most delicate tasks on this project. It's taking place right now as I write this entry, and if everything goes well we're on our way to a beautiful, sensitive new detector array for the second season of the SPT.

Whimsy

For over a week, I have spent almost all of my time inside the station. A huge crowd of SPT folks has recently arrived and there is so much activity out at the telescope that it is a little bit of a zoo over there. I am taking the opportunity to quietly work on analyzing data. I set myself up at around 8pm in the science lab at the station and work on software and analysis all night. It's great to have the time to dig in to some of the data, but the long hours at my laptop in the quiet of the night sometimes feel a little dull.

Once in a while, though, some odd event puctuates the routine. I thought I'd post the picture below in honor of my mom's birthday, which is today. It has just the sort of whimsical flavor that she appreciates. This is a picture I snapped out the window at my desk, when I randomly looked out and saw someone attempting to fly a homemade kite in some of the most outrageous South Pole winds we've had recently. As well as I could tell, the kite itself was made of a gigantic piece of black scrap plastic. It was clearly very heavy, and when it crashed it cut well into the snow. But the winds were intense that day and had no trouble lifting it and piloting it in erratic patterns across the sky. I watched this anonymous person battling with it for a while until he wandered away from my view. Given that it was an unusual time of day for anyone to be doing much, I wonder if he had any idea anyone might be witnessing his experiment.

SPT TV

Last week, I had the opportunity to drive the telescope around a lot. We're not actively observing, but we are making many upgrades to the software that controls the telescope, and trying to debug little things that didn't work as smoothly as we liked last season. The only time of day when I could do this was between the night and day shifts, for a couple of hours when nobody else needed access. All season we have been working on insulating the telescope and doing a better job of sealing the inside of the instrument (and the lab) from the elements. This work requires keeping the telescope stationary and often "docked", meaning that it is parked above the control room so that we can get access to the cabin that normally holds the receiver. So I had to squeeze in between the day and night shifts of carpenters and SPT scientists who might need to work around the telescope.

For a few days, I went out and undocked the telescope and moved it around a bit to do some motion tests with various changes to the software. Moving the telescope involves issuing commands by computer from inside the lab. There is something truly awesome (and very intimidating) about having an instrument of this size under your control. First of all, it can be downright terrifying. The thing moves at an improbably high speed. It is massive! You can't imagine what it's like to see a thing of that size move so fast, and so smoothly, until you have witnessed it. Operating something that large is just sort of scary. Especially when (as was the case last week) some of the software changes led at first to unpredictable behavior. One of the stranger things is that if you are moving the telescope from inside the control room (which is directly under it), you can't see where the telescope is going. You can see the inside moving (the gears are awesome, and the entire roof rotates if you swing the thing around in azimuth), but it is nevertheless unnerving not being able to see where it points.

So, I was quite happy when Erik Leitch brought over a camera and a little TV monitor and installed them. It's an old camera and an old TV previously used to keep an eye on the DASI telescope. It was a great improvement during the motion tests last week, if only to keep me from getting too jumpy! But there was something inherently funny about having an old black-and-white TV monitor in the midst of our otherwise high-tech and state-of-the-art laboratory.

A Monumental Effort

Today, what I should be writing about is the formal dedication ceremony for the new station. This morning, the flag was taken down once and for all from the top of the old dome, the previous South Pole Station, and transferred to a shiny new flagpole at the front of the new station. Distinguished guests were flown in for the ceremony and tours, including congressional respresentatives and the highest members of the NSF. Of course, since I'm on night shift, all of this took place while I was asleep. I could have stayed up for part of it, but I've been exhausted and I simply crashed. And then I slept in for the first time in weeks, which also meant that I missed the big dinner and most of the party to celebrate the formal opening of the new station.

The new station has been under construction for years, and for a newcomer like myself, it already feels like it's been here forever. I went into the dome last year, but already by that time the main living quarters were dismantled and mostly it was being used to store office supplies and snack foods in big racks criss-crossing the well-packed snow floor inside. For many people here, though, that dome was once home. Sometimes for the better part of many years, for the really dedicated members of the U.S. Antarctic Program who have wintered over many times. The work to build the new, modernized station has been intense, and today's formal dedication was the culmination of a massive, monumental effort. I could tell it was very sentimental for many members of the community.

For me, the official ceremonies do not have the personal significance that they do to people who have been involved in the South Pole Station for five years, a decade, or even two. But I am not without a good deal of awe for their accomplishments. Ironically, what made me most aware of the sheer scale of the project to keep a station going year-round at the South Pole, and most aware of the history and the people who have kept it going, was a recent tour of the grittier sides of station activites. Last week I went for a wander behind the station, looking in on all of the trade shops (carpenters, plumbers, electricians), the storage berms, and the out-of-the-way spots where old construction materials and decommissioned scientific equipment are stored, awaiting shipment back to the states.

New storage facilities are being built, as part of modernizing the station. But for years, elevated stretches of packed snow behind the station have been used to store construction materials, frozen food, and scraps of anything that might bear reuse in the future. This part of the station can feel like an endless sea of cardboard boxes, stacked pallets, and scrap metal.



Old scientific and communications materials are stored here, as well as anything else that breaks or becomes obsolete. It is all gradually on its way out, on return flights back to the U.S. But while it waits, exposed to the bare Antarctic elements, it conveys to the wandering observer a real sense of the history of this place and the unique mixture of basic life support services with technology and cutting-edge science that has always characterized daily life here.

Below are a few more pictures from my tour. A couple of these are of an old radome, an enclosure built to protect communications antennas. There are also stacks of giant empty spools, segments of arches used for storage facilities, and aisles of construction materials. All evidence of the massive, monumental scale of maintaining a research station here in all of its forms over the years.

Our New Sunroof

It's been a busy couple of weeks out at the telescope. SPT post-doc Brad Benson and graduate students Martin Lueker and Joaquin Vieira installed a new set of detectors into the SPT "receiver", which is essentially the camera for the telescope. A full array of detectors for our receiver consists of 1000 individual pixels. Each pixel is an exquisitely sensitive device that registers tiny temperature changes when it absorbs electromagnetic radiation like that from the early universe. We record electrical signals that tell us essentially how much heat each detector has absorbed as we scan the telescope to point at different locations in the sky. For now, however, what we are interested in doing is testing the new detectors without installing them in the telescope itself, and just seeing how they work. These detectors are a major research project in themselves, and each batch incorporates new features as we learn more and more about their performance.

Because these new detectors are so sensitive, the radiation from any warm object in their field of view can overwhelm them - essentially they overheat. For the tests that we wanted to perform, we installed the receiver on the optics cryostat,which holds the 1-meter secondary mirror for the telescope, and usually lives up in the big boom below the dish. We needed a way to point the window in the optics cryostat out at the sky without mounting it back up into the telescope. So, what we've been doing is opening up the sliding roof above the control room and using a big metal plate to bounce light from the sky into the optics cryostat, and eventually to the detectors. The sky is the coldest thing around, and it's also what the detectors are designed to see.

However, this has made for interesting working conditions in the lab. It's nice to get the natural light in there, but with the ceiling open to the South Pole environment, it's been freezing! For the last week I've been working in the control room at my laptop, controlling some of the tests and looking at data. I always have enough clothes on that I don't feel cold, but I really notice how much harder it is to type. The fingers just don't want to move quickly. At times, the wind was even blowing snow through the roof, and it was bizarre to have a bluster of ice flakes swirling around in the room.

Below is a picture of our sun roof. The big white vessel is the cryostat that holds our secondary mirror at a low enough temperature (around ten degrees above absolute zero) that its own radiation doesn't swamp our detectors. In this picture you can't see the red receiver cryostat bolted to it on the other side - that's what holds the detectors. The large silver box is the FTS, which I've described before. The big metal plate is what's making sure that our detectors are mostly looking at the sky.


We just finished two days of taking FTS measurements to characterize the response of the updated receiver to light of different frequencies. In the picture below you can see what it looked like from the other side of the setup. The lenses and windows in the center of the picture are part of the setup used to direct just a little bit of light from the FTS instrument into the receiver, so that it's not too much for the detectors to take. Mostly, the detectors are looking straight up into that sunny blue sky. We are working right under the telescope itself, and you can see the bottom of the telescope boom in the background. In this position, the telescope is on it's back, with the dish staring straight up as well.



It's been a busy couple of weeks but a successful one, and we're about ready to close up the sun roof and move on to the next projects for the season. It's never dull around here!

A strange thing to wake up to

A few days ago, I wandered into the galley for my morning (evening) coffee and saw two full C-130 flight crews sitting around looking a little dazed. This is very unusual - usually planes fly here from McMurdo, spend as little time as possible down on the ice while people and cargo are exchanged, and fly back immediately. Indeed, when I poked my head out the door by my room, there were two planes sitting out there with their engines off. It was almost surreal!


It is so cold here that it's very difficult to start the engines of these planes once they're turned off. For much of the year, it is too cold to even land them here. Weather back in McMurdo and along the coast must have been really extreme to force both planes to stay here. The crews for both flights stayed the night, and I felt sorry for them - the first night at this high altitude doesn't usually leave you very well rested. All night, operations crews gathered anything around that could generate heat to warm the engines for the next morning. As I was drifting off to sleep after my shift, I finally heard them go.