Echos of the Big Bang

I mentioned previously that Antarctica is a great place for us to do our science.  But is it really worth being away from family for more than a month over the holidays?  Maybe not, but the science we're up to is pretty cool.  Here's a cartoon of the early universe to give you a sense of what inspires us:

Early universe cartoon, by Wayne Hu

 Kinda looks like a lava-lamp, right?  If you don't find that mesmerizing, then feel free to skip this post.  For anyone else, the cartoon has three steps, labeled in the corner:

1.  "Oscillations": The Big Bang triggered echos, and those sound waves are the flashing vertical red and blue stripes.  The red stripes are hot and the blue ones a cold.  Those yellow dots are electrons and protons- the universe was too hot then for atoms to exist.
    
2. "Recombination": About 300,000 years after the Big Bang, the universe did cool enough for atoms to form.  Before that, the yellow dots scattered light rapidly, as depicted in the zig-zag yellow lines, making the universe look like a glowing thick fog.  This was going on since the Big Bang, but for simplicity, this cartoon only shows that scattering around the time that the atoms were forming.
    
3. "Streaming": After the atoms formed, light stopped scattering and essentially traveled in a strait line.  Each of those points emit light in all directions, but again, for simplicity, the cartoon only shows the rays that head towards an observer at the center of the figure.  That expanding doghnut shows what the sky looks like to that observer.  As time goes on, they can see more of the universe and it has hot and cool spots across they visible edge.

One final simplification: the cartoon only shows one sound wave from the Big Bang.  In actuality, there many different waves traveling in different directions (not just left to right) and with different spacings between stripes (or wavelengths, as we say).  All those waves create a series of spots that ultimately look like this to our telescope (1 week of data in Keck Array):

Map from Keck Array

This is a baby photo of the universe, with temperature shown in false color,  If the universe were your 80 year old grandfather, then this photo would have been from within 24 hours of birth.  Those random spots eventually pulled more and more matter into them and formed galaxies, stars, planets, and us.

You may be wondering now: "You skipped Christmas to look at random spots in the sky?…  at radio frequencies???"  Here's the catch: they're not quite random.  Some sizes of spots are brighter than others.  Here's a plot from South Pole Telescope showing the average brightness of a spot vs the spot size from their map:

Extracted from South Pole Telescope's map

You can see those regular bumps, which are essentially echos of the Big Bang.  The positions and relative heights of those bumps, as well as the curve leading down to the right have let scientists learn that:

1. Space between galaxies obeys standard high school geometry (it does't around black holes)
2. Our universe is just barely light enough that it won't re-collapse into a "Big Crunch"
3. There's five times as much "dark" matter than the stuff we're made of
4. The universe is mostly made of "Dark Energy," an anti-gravity force pushing the galaxies apart faster and faster.

It's hard for me to see how any other experiment will substantially improve that plot over what the South Pole Telescope has done… unless you're interested in polarization.  That's where our project comes in… but that's enough nerdiness for one post.

A White Christmas, with sun-dogs

Sun Dogs, credit Jeffrey Donenfeld

Merry Christmas from the South Pole.  Having lived most of my life in warm places, the idea of a "white" christmas is a novel one.  But this year, I had that one pretty well covered. 

The big festivity of the season is on Christmas eve: The Race Around the World, which is a 1.7km race that makes a loop around the south pole.  The 1st, 2nd, and 3rd place prizes for each gender were 10min, 7min, and 5min showers.  For reasons of fuel consumptions, we're ordinarily allowed only two 2-minute showers per week.

Unfortunately, I was working on data analysis all "night" long until 6AM that morning and the didn't have the energy to participate (not that I had much a chance of winning!).  So I slept through the race and ran it on my own today (Christmas).  It's really hard to run down here because the air is so cold, and it took me about 25 minutes to do that short course.  The cool air makes your lungs burn a bit.

On the plus side, I finally saw a "sun-dog."  When hexagonally shaped ice particles are suspended in the air, light refracts through them like a prism into a 22-degree radius halo around the sun.  This rainbow effect is pretty common.  Less common is when the particles align vertically, such that the light tends to refract along an axis parallel to the horizon, giving rise to multiple images of the sun.  This happens in the Northern US as well, but again, I wouldn't have had much opportunity to see these having grown up in California and Texas.

I didn't have my camera with me on my run (it's batteries do poorly in the cold weather), but one of the cooks at the base here, managed a good photo of one back in Novemmber.  That's shown above.  These are more common at the beginning and end of the summer when the sun is closer to the horizon and the cooler air helps align the ice particles better.

Endless Summer Days

12:12 AM today (December 22nd) was the Summer Solstice, which means that it is the longest day of the year in the Southern Hemisphere (and shortest back home).  However, in the center of Antarctica, where the sun is up constantly this time of year, it just means that the sun is the highest elevation all year long.  At the South Pole, the sun just travels in a line parallel to the horizon as seen in this video:

The video is a time-laps of the sky during one day, although it was almost certainly taken at night (i.e. winter) with the camera rigged to provide high enough sensitivity such that it looks like it's day out.  So you're actually looking at the moon.  Notice that the moon drifts along the horizon rather than away/towards it as we're used to. 

Measuring the Earth's tilt at the equinox; SPT in background

I took a break from work today to measure the tilt of the Earth for fun.  This tool is a sextant, designed to let the user measure the inclination of an object with respect to the horizon.  I measured that the sun is 23.4 degrees above the horizon, thus the Earth's rotational axis is at a 23.4 degree tilt with respect to it's orbital plane.

This technique was used by both Admussen and Scott to navigate to the pole 100 years ago.  Remember that a magnetic compass is useless near the magnetic pole of the Earth, so you're stuck using a sextant and celestial bodies.  If you're not standing at the pole, the sun's elevation will bob up and down over the course of a day, so repeated measurements can help guide you to the Southern-most point on the globe.  In fact, when Admussen reached the pole, he stayed for three days to conduct repeated measurements of this sort to definitively prove he had made it.  An experienced user can determine their latitude to within a mile with this tool.

There's another treat about halfway into the above video, when you can see the Aurora Australis (Southern Lights).  These are the same phenomenon as the Northern Lights, arising when charged particles from the Sun are directed along magnetic field lines to the polar regions, where they collide with gas in the upper atmosphere, causing a glow.  I won't get to see this in person (thank god!)

One final cute thing in that video: looking at the beginning, notice that the stars do not change there orientation with respect to horizon.  That's not the case for mid-latitudes where the constellations "rotate", as seen in this youtube video:

This actually presents a mild-challenge to our experiments since the mechanics of our telescopes only let us scan the sky parallel to the horizon (in azimuth, as we say).  This can give rise to stripy looking maps that concentrate certain noise in just on direction.  Mid-latitude telescopes essentially probe more spatial modes on the sky thanks to that rotation.

The Dark Sector

Keck Array at night, credit Keith Vanderlinde

The Dark Sector is a Radio Quiet (or "dark") area of the station kept quiet for radio and submillimeter telescopes.  This is where I have spent most of my working time thus far.  It's about a 3/4 mile walk from the dormitory, but it can be a moderate work-out between the snow, cold, and high altitude.  The path also crosses the runway, which means you can get stuck waiting on a plane at the wrong time of day.  To get a feel for this commute, here's a video that my friend and coworker Martin shot a few years back while in grad school:

The dark sector includes the IceCube facility, the Dark Sector Laboratory (DSL), and the Martin A Pomeritz Observatory (MAPO).  The most imposing structure in the entire base is probably the South Pole Telescope house in a structure attached to DSL:

South Pole Telescope (left) and BICEP-2 (right)

 I've never worked on this, although several friends have and there a plans in the works to upgrade their camera with the detectors that I developed in Grad School.  That large dish is 10m in diameter, which gives them sub-arcminute resolution on the sky.  They've used this telescope to search for distant galaxy clusters and are currently looking for a signature that will constrain the total mass of all the neutrinos.

BICEP-2 camera in the lab with spectrometer on top

By comparison, our telescopes are smaller.  Above is BICEP-2, which is housed in DSL, right next to SPT.  In contrast to SPT, it has no mirrors; It looks like a spy-glass with a couple of lenses and some filters.  Because the lenses are naturally smaller than a 10m mirror, it's resolution is limited to around a half degrees (30 arcmin).  However, these are much cheaper than SPT, which means you can build several and attain much higher sensitivity (lower collective noise). 

And that's exactly what we did- we built five more.  This is the Keck Array (aka SPUD) housed in MAPO and is the project I spend most of my time on.

Keck Array, with two cameras off the mount in the lab

Shoveling snow from the ground shield

 We are currently decommissioning BICEP-2 and pulling the best parts from it for use in an upgrade to one of the Keck cameras.  Perhaps I'll return next year to deploy BICEP-3 in that mount if it gets deployment funds.

BICEP-mount, empty after three years

 Those wooden structures around the telescopes are ground-shields, designed to prevent the telescope from seeing thermal emission from the ground.  SPT has one too, although it is attached to the telescope mount and moves with the instrument.  Here's on old one adjacent to MAPO used for the VIPER telescope in the 90s and by ACBAR in the 2000s.  It has been abandoned for a better part of a decade.

Abandoned Ground Shield

Have a look youself- Google Street Maps has even made it down here: DSL on Google Maps.

And finally, the world's coldest outhouse:

Inside the base

Robert Scott's 1912 journal entry upon reaching the Pole was "Great God! This is an awful place".  I'm not quite sure what he was expecting.  However, if he had just waited a century, he would have found a very accommodating dormitory that feels almost like a ski-lodge.

My room is pretty spartan and small, about the size of our bathroom back in California.  It reminds me of my office at Caltech- no windows!

Room

Science Lab

For those who don't want/need to schlep all the way to their experiments on a given day, there's a spacious general use lab where each project has some space.

The Galley serves 3 hot meals a day.  The cooking is pretty good, although I already miss fresh fruits and vegetables.  I brought a rapidly dwindling supply of avocados from Christchurch, which has made making friends at dinner easy.  If only I'd brought some arugula or kale…

The Galley

Kitchen

They used to have fresh vegetables grown in the green house, but due to cost cutting measures implemented by the new contractor (Lockhead), the green house is currently not producing anything:

Greenhouse

There are a number of recreation rooms, a general store that sells snacks and alcohol (only open 1 hour a day) and a gym complete with Basketball Court.  There's even a sauna.  Ladies and Gentlemen, your tax dollars at work!

Gym on balcony over Basketball court

I took some videos while walking around this place in the middle of the "night," but bandwidth limitations prevent me from sending those up.  Fortunately, our esteemed colleague from South Pole Telescope, Tom Crawford, has uploaded a similar video:

All in all, it's pretty nice digs- it's a shame we're working too hard to enjoy it much.  But no one should think that I'm "roughing it" down here!

Finally at the South Pole

At the South Pole

I finally arrived arrived at pole yesterday, although not without a little more delay.  We drove out to the airstrip on the Ross Ice Shelf at 6:45AM only for our pilot to discover a hydraulic issue with the plane, so we waited in the world's most desolate airport for the next four hours while they fixed it.

Terminal, made from an unheated trailer

Mt. Erebus, an active Volcano on Ross Island visible from the airport

The views of the Antarctic interior on the plane were a rare treat:

Transantarctic Mountains

Silhouette of plane on the ice while landing at Pole.

In total, this trip took 6 calendar days, 5 actual ones.  It didn't used to be so easy and quick.  The base's full name is Admussen-Scott South Pole Station, in honor of the first two people to get to the South Pole.  As my friend Zak quipped, Amundsen was from from Norway, knew all about dog-sledding, and returned home a Niel-Armstrong-style national hero as the first person to get at the South Pole.  Scott fancied himself a gentleman explorer who insisted on using ponies for transportation.  He got there second and froze to death on the way back out.  You can all read about them in the wikipedia links above.

I've had an easy go compared to Scott, only suffering from some mld altitude sickness.  The elevation here is 9300 ft, but the atmosphere is thinner at the poles than mid-latitudes, so the effective altitude is more like 11,000 ft.  Low pressure from weather can further increase the effective elevation beyond that.  Were it not for the ice cap, that elevation would be near sea-level.  The ice-sheet is 1.7 miles thick, forming a large plateau that covers most of the continent.  It's pretty flat and featureless as you can see from pictures of the base:

Dormitory at Admussen-Scott Station

Another view of the dormitory

The actual South Pole has to be re-marked each year thanks to the ice-cap shifting.  The winter staff includes a machinist, who's jobs include machining a new marker for the following year.

South Pole Marker for 2012

There's also a ceremonial pole that looks pretty much like the childhood image that most of us had of the north pole.  That's the photo at the top.

Ballooning

My flight to pole was scheduled at 5 in the evening, but we were told to be ready to go in the event that the flight moved up in response to weather being bad elsewhere in the continent.  So I spent the whole day in the town; in the end, my flight was canceled.

This travel restriction was really too bad; I had made plans through some friends working on EBEX to go visit as they prepare for their planned balloon flight this weekend.  EBEX has similar science goals as the other experiments that I work on, but will do the measurement from a high altitude balloon at ~120,000 feet.

Remember how turbulence in the atmosphere can add noise to our measurements?  You should think of a balloon as a budget alternative to a satellite: they climb above most of the atmosphere and thus attain sensitivity similar to a satellite.  Antarctica has a novel weather system that causes these balloons to circle the continent, and in principle an experiment can observe for a month.  Thanks to the higher attainable sensitivity at high altitude, one month of their measurement is comparable to a couple years of observing on the ground.  So there's a decent chance they will catch up with our team that has been integrating since 2010.

Here's a link to a short youtube video showing a launch of one balloon out on the Ross Ice Shelf.
Long Duration Balloon (LDB) launch

The downside is that Ballooning is risky business compared to ground based experiments.  This season, Mark Devlin's team will also be re-flying the BLAST experiment to study magnetic fields in star-forming regions.  You can watch his interview on the Colbert Report to get a sense of some of the risks:
Ballooning on colbert Report

McMurdo Station

McMurdo is the largest town in Antarctica, and this is it:


The town is located here:

I took a few photos in town at 1am after my flight, but the sun doesn't set down here so you can only tell its late because there's no one walking around.

Outside of the Coffee Shop, dates back to the early 1960s

Chapel

Overlooking the Ross Sea

The first dwelling in the area, just outside of town, is a supply depot that Robert Scott built in 1902 for one of his expeditions (called Discovery Hut):

I'm told that mummified seal has also been there since the early 20th century as well.  The temperature seldom climbs above 0C, so these sorts of things are well preserved.  You can make special arrangements to go inside the hut, but we did not.  Fortunately, Google did for a couple of the other huts on Ross Island, and they took "Street View" Photos of Scott's Hut and Shackleton's Hut.  Researchers recently found a few cases of Scotch from 1908 under the floorboards of Shackleton's Hut, which you can read about here.

Here's a video I took showing a 360 pan of the sea and surrounding mountains over McMurdo Station:

Ice Flight

The "ice-flight" from Christchurch to McMurdo Station on the Ross Sea of Antarctica is roughly equivalent in distance to flying New York to San Francisco, but it takes eight to nine hours because we lumber down in a 1960s era LC-130 US Air Force turbo-prop plane.  Below is a photo of the exterior after landing.

LC-130 turbo-prop on the Ross Ice Shelf

The landing gear has wheels that retract through gaps in the skis, which allows for landing on the frozen sea next to McMurdo.

Here are some photos of the plane's interior:

There's ample leg-room and spare seats, but the seat-backs improvised from netting get old after a few hours.  The front half of the plane is filled with passengers and the back half is used for gear.  I'm not sure what that large engine looking thing is in the back.

I had a friend in Grad school who had been an undergrad at Harvey Mudd.  He had this story about a road trip to New Orleans for Mardi Gras where they bought a used city bus and filled it with old couches.  They also made a urinal from a funnel, surgical tubing, and a drilled hole in the side of the bus.  I imagine it it was similar in spirit to the one on the plane seen below.  The bathroom itself was improvised from a tarp.

The restroom

Urinal

The Air-force issues ear-plugs because the engines are LOUD- there's little chance for conversation on the eight hour flight… or possibly the 14-16 hour flight!  Weather conditions are unpredictable and the flights have been known to get most of the way there and then "boomerang" back to New Zealand because of unsafe landing conditions.  We were lucky and managed the trip in just one day.  We're only a week shy of the Summer solstice down here, which tends to offer the best weather of the season.  I hope my return in mid-January is as seamless.

The plane lands at the edge of the Ross Ice Shelf, about 15 miles from McMurdo.  As a final sucker-punch after the long flight, the bus ride takes about 1.5 hours because the bus rides at ~10mph so as to not damage the "road."

Christchurch

Our last taste of civilization before departing for Antarctica is the city of Christchurch on New Zealand's South Island.  Many of my friends who are veterans of this trip speak of the city fondly, and it's not hard to see why.  The weather is great (reminds me of Portland), the countryside just outside the city looks spectacular, and the people here are nice to a fault.  As I ran errands today, I had two different vendors offer me rides during their breaks to help me get everything done.  I gratefully accepted both.

Which is why the Earthquake over a year ago is so heartbraking.  At magnitude 6, it wasn't that strong by California standards, but context is everything.  The epicenter was shallow (3 miles) and right under the city. The city is built on a flat coastal plane that is mostly sediment, so liquifaction was a large problem too.

The people here are actively rebuilding their city, but it's still a work in progress, with most of the down-town and historic core closed off and in ruins.  I attached a few photos.

City Library (I think)

Christchurch Cathedral

Poorly hidden UFO- probably responsible for most of the damage

Church near my hotel

Why go to the South Pole?

I'm currently stuck in Sydney airport on a 7 hour layover.  Australian immegration law bars me from leaving the airport (it's a boot-able offense) and my attempts to video the rotational handedness of a toilet flushing ended poorly (these toilets have jets that direct water radially inward!).  So as I sip my Victorian Bitter (how is that the Aussies are know for their beer?), I figured I'd answer a question that several friends have asked: "why do we need to go to the South Pole?"  Why not do this somewhere closer, let's say Mt Palomar near San Diego or on Mt Wilson above LA?

The answers are that:
1) it's really dry at the South Pole and
2) the air is really still there over the winter

We're trying to look at microwaves (technically millimeter waves) left over from the Big Bang.  We're stuck looking at microwaves because our expanding universe has stretched the wavelengths of the Big-Bang's afterglow from infrared into the microwave range.  Wayne Hu from University of Chicago is well know for his animated gifs to explain cosmology, and here's his explanation of how our universe's expansions not only drags the galaxies apart but also stretches wavelengths of light into the red end of the spectrum.

Most people experience microwaves at home with their microwave ovens.  Those work because water in your food absorbs microwaves.  However, the water vapor in our atmosphere also absorbs the microwaves coming in from the heavens, so in our business it pays to set up shop somewhere very dry.  The center of Antarctica, technically a desert,  is one of the driest places in the world because all of the water freezes out of the air (The Atacama Desert in Chile is also very good).  There's nothing particularly special about the South Pole, except that it happens to be in the middle of Antarctica and has lots of support infrastructure courtesy of the NSF and US Navy.

The stable air is just as important.  Generations of kids have grown up learning about twinkling stars from nurse rhymes, but it's a real pain for astronomy.  Stars and distant city lights "twinkle" because of atmospheric turbulence, and it can make images look fuzzy.  My friend Christoph Baranec designs telescopes with "adaptive optics" that can correct for turbulence with deformable mirrors.  Below are pictures he took of Jupiter with his Robo-AO system on and off:

That can work well for visible and infrared light, but those techniques are not as useful for microwaves.  Our images are much coarser, so turbulence doesn't appreciably distort our images-  it just contributes unwanted noise that can make the measurement take (much) longer.  The beauty of Antarctica is that the sun sets once a year - in March- and doesn't rise until September.  As a result, there's no daily heating and cooling of water or land-masses that might generate high altitude winds.  So we get 6 months of pristine uninterrupted viewing.

Heading South Today

I created this blog to describe my travels to and from the South Pole this winter to curious friends and family.  I've always thought "Droppin' the MKIDS off at the pole" would make for a great title for a conference talk-  after all, puns are the highest form of humor, right?  For better or worse, that occasion has never presented itself, so I re-purposed the name for this blog.  Technically, the detectors we use at our South Pole experiments are TES-bolometers and not MKIDS, but if you can appreciate that difference then you're not really the target audience of this blog.

Antenna-coupled bolometer fo Keck (8mm wide)

I've never been to the Pole, but my detectors have- so I figured it was time to pay them a visit.  I've spent the past couple years as a post-doc at Caltech & NASA-JPL refining the detectors that we use in the Keck Array Telescope (not the famed Mauna Kea Keck Telescope).  Those are shown at left.  Close cousins of these detectors will fly in the balloon-borne SPIDER telescope next winter (to be flown out of McMurdo in Antarctica).  If the funding Gods smile upon us, we may even bring down an additional project called BICEP-3 next year with even more of those.  In a couple years, the South Pole Telescope will replace their camera with one that uses the detectors I developed for my doctoral thesis at Berkeley- those are shown below at right.

Prototype detector for SPT-3G, ~5mm accross

I will be at the base from December 14-Janurary 15.  The Keck Array deployed at the end of 2010.  Since then, we have dramatically improved the detectors we make at JPL and will be replacing some of the existing ones this year.   My work down there will primarily be preparing the cameras for the new detectors that one of my colleagues will bring down at the beginning of January.  We will also feng shui some of the detectors currently there to maximize sensitivity of the overall experiment.