For many years, the geodesic dome at the South Pole has been an iconic structure, the image of the place. The dome was built in the 1970’s by Navy Seabees. Unheated and with a snow/ice floor, it provided a windbreak for the small buildings inside it. In all my previous trips, I walked into the dome to go to the Galley for meals three times a day – I slept out in “summer camp”, which is a collection of (upgraded) Korean-war era double-wall half-cylinder tents known as Jamesways. (I really really like the new station – much easier to live in!)

This year, starting tomorrow in fact, they are taking apart the dome and shipping all the material back to the US. Yesterday a group of us walked over there to take pictures; the buildings have been moved out, making it an eerie sight on the inside, but much easier to grasp the scale of the dome. It’s an amazing structure, with lots of history, and it will be sad to see it come down.

The old dome, viewed from the Galley in the new station. The orange building on the left is Skylab, which used to house a variety of experiments doing things such as looking at the aurora. The dome had about 4 or 5 similar-looking buildings (square, orange) in it. The dome is now empty (see next photo), and Skylab is coming down soon.

A picture of the inside of the dome, now empty, ready to come down.

A picture of a torn panel, showing how thin the aluminum sheet is; Until I saw this, for some reason I always imagined that the aluminum triangles were much thicker!

Video: Old Dome, walking in.
Video: Old Dome, from inside.

Happy Thanksgiving (a little belated) to everyone!

Down here, we celebrate Thanksgiving on Saturday (today) rather than Thursday, so that the support folks can have a 2-day weekend. They normally work Mondays through Saturdays, and have Sundays off. So, tonight is the special holiday dinner in the Galley.

I haven’t posted any pictures of the Galley in normal times, so here’s a movie of showing what it looks like at a normal dinnertime. It has great windows looking outside, and enough seating that despite the fact that we have 250 people on station it is rarely very crowded. We’ve had good food here this year, with a surprising amount of fresh fruit and greens, which have at least a 2 day travel time from New Zealand to here (in the best of weather)!

Video: The Galley at Dinnertime
A quick tour of the dining room, known as the “galley”.

Today, with all the electronics working and the camera cooling, we got dirty. A telescope as big as the SPT requires a lot of grease… in the bearings, on the gears, all the moving parts.

We donned our greasy clothes (I was lucky enough to have gotten some coveralls from the heavy machine shop here), and went to work.

Here I am, all dressed up in coveralls, ready to get dirty.

Video: Getting ready for Grease Day!

Abby paints grease onto the azimuth gear…

Video: Abby greases the Azimuth gear.

Liz and I head up to the place where the receiver sits, where a bunch of motors can move it around to focus the telescope; those motors need greasing once per year. It’s a 2 person job because it’s so hard to get to the grease points!

It’s been a few day since I wrote here… largely due to two tales of woe.

First and foremost, my laptop is dying. The charger no longer charges it, the battery is almost empty, and after googling and talking to folks in IT here and talking to apple, there’s no way to fix it without giving it back to Apple to have them work on it. So, I’m laptopless for the next 2 weeks. I’ve taken over a linux workstation (with two big screens, so at least it’s an upgrade in that sense), and have figured out how to download pictures from my camera, but it’s not iphone compatible.

Having your laptop break brings home the fact that when you’re here, when something breaks you either have to fix it yourself, go without, or wait a looonnnnnng time for a replacement to come in.

Which brings us to the other tale of woe: the electronics that read out temperatures inside the big optics cryostat stopped working when we brought them down from the telescope to the control room so they’d be next to the cryostat, since that’s where we’re testing everything. The first indication was that the computer wasn’t getting any of the data it should; we quickly realized that the problem was probably with one of the timing signals sent from a “timing box” over some wires to the temperature-reading electronics box.

We have lots of custom-designed and built electronics here, to read out the signals from our detectors, temperatures of the cryostats, control the telescope, etc etc. Since we know those things can break and we’re a long way from Radio Shack, we stock a lot of extra components and parts here. A good part of making an experiment like ours work is in fixing all the problems that crop up; so this broken electronics box, while annoying, was just another hurdle to get over.

Ken Aird (another SPTer, from Chicago) and I spent a couple hours on Tuesday, then 5 more hours on Wednesday, tracing down the problem. We thought it was in the temperature-reading box, and pulled out a circuit board and replaced a tiny integrated circuit in there… but that didn’t change the behaviour at all. Looking at the signals more closely, we decided the signals coming from the timing box were a bit suspicious looking and decided to swap out the integrated circuit that sends those signals… and voir la, it worked!

Just in time for dinner, in fact. 🙂

So, down a laptop but having fixed the electronics yesterday, a new day begins. The camera cooldown is going well, and we should be able to start testing detectors on Sunday.

The optics temperature-readout box, which we thought was the source of our troubles…

The board we pulled out of that box; Ken replaced one of the small 8 pin chips on there, using a soldering iron under a microscope to do so.

The actual source of our problems was an easy-to-replace chip in this, the timing box. Sometimes it takes a long day to find the easy solution.

Last night we sealed up the camera and put it back on the optics cryostat. I took an absurd amount of video to show you what this involved… anyone who actually watches all of these should email me for a prize:

Video: Mating the cryostats (part 0)
Video: Mating the cryostats (part 1)
Video: Mating the cryostats (part 2)
Video: Mating the cryostats (part 3)
Video: Mating the cryostats (part 4)
Video: Mating the cryostats (part 5)
Video: Mating the cryostats (part 6)

We also started pumping the air out of the cryostats, which will continue for the next day or so… then we get to start cooling the camera and secondary mirror down to cryogenic temperatures so we can test them. That pumping and cooling process will probably take 4-5 days, during which we’ll get electronics set up and do some telescope maintenance.

Last night we were sooooo close to having the whole camera put back together… and we noticed that some of the black material we’d installed (to cut down on internal reflections in the camera) was flaking onto a lens. So, we vacuumed it out as best we could, and then did a very scientific test

Video: Very Scientific Test

to see if any more black stuff fell onto the lens. Hard to see in the video, but the verdict was bad – it did. We also noticed the black stuff was in the way of part of the optical beam, and needed to be thinned. Big setback, but our intrepid crew decided on a fix, took apart the cryostat again, fixed everything and got it all back together by dinner today (Sunday).

Here’s a video of the focal plane going back into the cryostat after the fix, a major milestone in our reassembly:

Video: Focal plane goes back into the dewar

Brad is giving the station’s Sunday science lecture tonight; afterwards, we’ll head out and finish closing up the camera, and put it on the optics cryostat. Keep all fingers and toes crossed!

It’s Saturday here, and we’ve been working to take apart the camera and start the modifications. Here are two movies:

Brad taking the focal plane out of the dewar.

Abby taking a wedge of detectors out of the focal plane.

We’re a long way into the modifications, actually… we’re going back out tonight to finish things off and start closing up the cryostat. If all goes well, tomorrow we’ll finish closing and start the weeklong process of pumping it out and cooling it down.

(Keeping fingers crossed)

On other notes… it’s still cold here (surprise surprise!). Here’s a movie of me all bundled up, headed out to the telescope to work. Even the very light breeze here tries to freeze your face… we do this walk back and forth 3 times a day, and because of the altitude and cold it feels like good exercise!

Walking to Work.

Last night, the camera was finally warm enough inside to take it off the optics cryostat, so we did that and started taking apart the camera so we can do our work on it. We’ll do all the modifications over the next 2-3 days, then close it up and start cooling it all down again so we can test whether the upgrades worked. (If they cause problems, we’ll have to open it up again to fix them… hope for no problems!)

Here’s a picture of me (what we call a “hero shot”) with both cryostats after we separated them. The big white one contains some of our optics, and the red one in front is the camera.

You might ask “Why are you wearing a hat and warm overalls inside?” Good question. The overalls are heavily insulated, very warm. I’m also wearing my fleece jacket. With all the electronics and compressors that operate our instrument turned off, the room underneath the telescope is pretty cool – about 50F or so. So it’s kind of like working in a warm refrigerator. After a long day working, I tend to get cold more easily, and it’s nice to be in something that keeps you warm at that point.

In this next picture, I’m actually working. 🙂 Abby and I are removing the various layers that cover up the focal plane of the instrument, so it can get very very cold (down to 1/3 of a degree Kelvin, right near absolute zero). We’re wearing those white gloves so we don’t get any finger-grease on the parts inside the cryostat.

Finally, here’s what is inside. This is the backside of the focal plane, so you can’t see the detectors. What you do see is all the wiring and the thermal connections to various stages of refrigeration; the coolers are off to the side, out of the picture inside the cryostat.

By the time we got to this point, it was about 11pm, so we stopped and headed in for the midnight meal (“midrats”). Tomorrow we take the focal plane out and get to work!

It’s pretty cold here – hovering around -40F (which also happens to be -40C) or so, but only 6knots of wind which puts the windchill at about -60F. On the walk out to the telescope, any exposed skin gets really really cold, to the point of hurting. I’ve been walking out with just sunglasses, a hat, and a neck gaiter, and getting cold and having to put up my hood to cut the wind. Getting tired of that, I followed the lead of some others down here and modified my ski goggles to cover my nose. Here’s a video showing them, filmed inside our science lab here at the station.

Modified Goggles video

Feel free to try this at home!

Today – my first full day at the Pole – we went out to the telescope to start our work. We’re here to do some modifications to the camera that will help improve the pictures we take with it – more on that later. The camera (also known as the “receiver”, since that’s what we call radio-frequency detectors) is housed up in the telescope, and it takes a lot of work to get it down so we can work on it.

First, though, here’s a glory shot of me with the telescope in the background – the telescope is 30 feet in diameter, my head is much smaller – really!

That’s what we did today; we moved the telescope so the “receiver cabin” was docked with the room of the control room that sits beneath the telescope, opened up some big doors between the ceiling of that room and the floor of the receiver cabin, and lowered the whole 2000 pound package from the telescope into that room.

Before we could do that, we had to unplug all the cables from the electronics that read out the camera – lots of cables, because there’s about 1000 channels of data coming from the receiver into the data system. We also had to disconnect all the hoses that cool the receiver and optics down to cryogenic (4K and below) temperatures. Then, we carefully lowered everything using some chain hoists – kind of like mini hand-operated cranes. Here’s a picture of two of the grad students (Liz from UC Berkeley at upper middle, Abby from U. Chicago on the right) working to unhook everything before we lowered it.

Also, here’s movie (a little bit shaky again -I’ve got to get a steadier hand!) from up inside the receiver cabin before we lowered the whole thing down to the ground.

Inside Receiver cabin before lowering