After four nights at the West Antarctic Ice Sheet Divide field camp, an LC-130 plane finally landed and brought us back to McMurdo Station, the final stop on the trip before leaving the continent. WAIS Divide gets some of the worst weather in Antarctica — but that's why it's the home of one of the most highly anticipated ice-coring projects in the world.

Ice cores trap samples of the atmosphere in small bubbles, offering snapshots of ancient atmospheric conditions to the scientists who dig the ice up and extract the gas. If the ice is thick enough, paleoclimatologists can count the layers back tens of thousands of years to catalog what the climate was like when that ice fell from the sky as snow. Other methods such as comparison with methane records can be used to date the ice, but thicker layers allow for greater temporal resolution and smaller error bars on the final analysis years down the road. And to have thick layers, you need lots of annual snowfall, so that's why glaciologists drill at WAIS: It gets about half a metre of snow per year (not too shabby for Earth's driest continent), creating beautiful annual ice layers 22 centimeters thick.

A look at the science of the WAIS Divide ice coring project will be forthcoming in the print edition of Nature, but in the meantime I thought it would be neat to see how drillers pull up 3.5 kilometers of ice, the last few metres of which are over 100,000 years old. I've spent lots of time in the drilling arch over the last few days, and I was fortunate enough to see the ice coring operation in action.

Ice cores like to tease the drillers who pull them up: The Deep Ice Sheet Coring Drill at WAIS grabs ice in 3.3-meter segments (each grabbing is called a "run"), so the closer you get to the bedrock and the further back you go in time, the longer it takes the drill to swim down the hole and reach the next piece. "Swim" really is the operative term: The hole is filled with a drilling fluid to maintain its structural integrity, so the drill is outfitted with a pump that allows it to move quickly down the hole. When the drill comes up, drilling fluid spills out, giving the core a nice fresh sheen.

An automated crane-like system lifts the barrel of the drill to a transfer station, where the core is pushed out of the barrel through a hole to the processing side of the drilling arch. The drilling side remains at whatever temperature it is outside (about -10C to -14C), but the processing side, or "science side," is cooled to about -27C, and is never allowed to get warmer than -20C, the temperature at which certain gases will begin to leak out of the core. To keep the room cool, four refrigerator units make the science side quite chilly. Suffice it to say that air conditioning in Antarctica has been one of the major surprises of the trip.

Once the core is pushed through to the science side, the core handlers take over. Core handling is, by admission of the people who do it, a rather thankless trade, but all the core handlers are highly qualified scientists doing a very important job. They take a slew of measurements, mark up the core with lines to indicate its proper orientation, and carefully document the condition of the core, including any fractures or breaks the core may have suffered. One of the most important measurements is the precise length of the segment: There is no depth-o-meter to know how far down a core came from, so the handlers measure depth by adding the length of each piece to that of the previous piece and making a cumulative measurement. Certain landmark events like volcanic eruptions (which show up as ash layers in the core) can be used to roughly check the measurements, but scientists are interested in millimetre-scale features of the core, so precise measurements are crucial.

One factor that can make this measurement tricky is the break made by the drill at the end of each run to separate the core from what will become the next segment. Usually these breaks are clean, but sometimes they can be diagonal, making it difficult to say exactly how long a segment of core is. Should you end your measurement when the core ceases to be cylindrical? Or should you extend it to very tip of the ice, even if it's a thin point? To solve this problem, the core handlers keep the previous segment of core on hand to be butted up against each new segment, and they take the measurement of the two-core combo, which fits together even with diagonal breaks.

Many ice coring projects make a number of scientific measurements on-site, but the remoteness of the WAIS Divide camp and the costs of getting material out there mean handlers can only take the basic measurements mentioned earlier. After that, the ice sits for a few days until it becomes less cloudy, and can be inspected again if anything special comes up. On my visit, we were shown a piece of core from a depth of 1,586m (approximate age: 8,200 years ago) with an ash layer believed to have originated from the eruption of Mt. Takahe, a volcano a few hundred miles from WAIS Divide.

After the initial processing stages, the ice can remain on site for quite a while. Last year, drillers were pulling up ice from the "brittle zone," an area from about 500m in depth to 1,200m, where the ice is known to crack and break into pieces even if handled delicately. Last year's brittle ice was still on site, "resting" until it could be moved, so this year's ice will stay on site another year as well (it would be shipped off, but there are only resources to ship one season of ice each year), which gives perspective to the speed of ice-core research. Ken Taylor, the chief scientist at WAIS, told me he doesn't expect to see publications from the ice pulled up today for another 4-5 years! First, there's the year of sitting, then another half-year to get to the U.S. National Ice Core Laboratory in Denver, Colorado, and another few months to make it to labs across the world. That's nearly two years just to get into the hands of scientists, who are suddenly bombarded with a whole drilling season's worth of ice. If it takes them two years to measure the ice, analyze the data and write up and publish the results (a breakneck pace!), that would be about 4 years from drilling time to publication, and it could certainly take longer.

But it's worth it to be patient. The work going on here is some of the most important in all of climate science.

Editor's note: See Chaz's full story about the WAIS Divide drilling project here.

Posted by Alex Witze on January 20, 2010
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Editor's note: Chaz has flown to the camp for the West Antarctic Ice Sheet Divide project, where he has limited internet connectivity. Storms also suggest that he may be there for a couple of days before he can hop a plane ride out. Posting will resume when he re-emerges back at McMurdo.

Posted by Alex Witze on January 16, 2010
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Posted on behalf of Chaz Firestone

Say the word "telescope" at the South Pole and you'll be directed to one of two large dishes at the Martin A. Pomerantz Observatory, each of which searches the sky for cosmic microwave background radiation left over from the Big Bang: The South Pole Telescope and BICEP, the brawny name for Background Imaging of Cosmic Extragalactic Polarization. But there is a third telescope at the Pole, though it doesn't really look like one. That's because it's pointed downward.

IceCube is an astrophysics project at the Pole that looks for traces of neutrinos, invisible particles churned out by nuclear reactions. They can originate from distant supernovae, from our own Sun and even from man-made nuclear reactors, and they are around us all the time, passing through matter with ease. This last property, owing to their lack of charge and tiny mass, makes them notoriously elusive, and neutrino collisions are rare events — so rare, in fact, that you have to go all the way to the South Pole to get the best view of them.

When a neutrino collides with an atom, a byproduct of the collision is a muon, which emits a faint blue light that can be detected by a sensitive enough instrument. Traditionally, neutrino collisions are detected in liquid water, which is used as a medium by labs in Japan and Canada. But one of the insights of IceCube was to realize that neutrino detection would work just as well in ice — and there's plenty of that in Antarctica.

Yesterday, I met with Mark Krasberg, a physicist at the University of Wisconsin who works at IceCube, the largest neutrino detector in the world. IceCube searches for high-energy neutrinos with a more interesting source than our modest Sun: violent astrophysical events like exploding stars and colliding galaxies. Here's how it works:

With a hot water drill, technicians bore a hole (pictured, above right) 2.4 kilometers deep. In it, they place a string of digital optical modules (DOMs) in the bottom kilometer of the hole. The DOMs (pictured, right) will remain in those holes for tens of thousands of years, and are built to detect that faint blue light from muons in the crystal-clear Antarctic ice. (With that long a shelf life, researchers like to make themselves a part of history by signing their names on the DOMs, which I had the opportunity to do.) After a neutrino collision, the resultant muon travels along the same course as the neutrino that produced it, so astrophysicists can retrace the trajectory of the muon to determine the source of the neutrino, much as a forensics specialist might do ballistics work. Even though only a few neutrinos from cosmogenic events (maybe just two or three!) will collide with an atom of ice each hour in a block 1 cubic kilometer in volume, the equipment at IceCube is sensitive enough to capitalize on the few collisions it observes.

Though the telescope is located just a few hundred meters from the South Pole itself, it actually surveys the northern sky for these violent astrophysical events. As mentioned above, neutrinos can originate from all kinds of sources, but the high-energy neutrinos IceCube is after (reaching energies of a peta electron volt!) have a better chance at passing through the Earth than lower-energy, garden-variety neutrinos. By searching southern ice for neutrinos originating from the north, scientists use the Earth itself as a filter, isolating the neutrinos of interest.

What's all the trouble for? As Krasberg explained, certain astrophysical events and bodies aren't easily detectable by traditional optical and radio telescopes. But neutrinos, which can pass through the interstellar medium with even less attenuation than photons, allow astrophysicists the unique opportunity to "see" these cosmogenic events. The end goal, Krasberg said, is to build on work done by IceCube predecessor, the Antarctic Muon And Neutrino Detector Array (AMANDA), to construct a detailed map of (half) the sky's distant astrophysical bodies.

Posted by Alex Witze on January 12, 2010
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Posted on behalf of Chaz Firestone

At long last, we've reached the South Pole, nearly a century after Roald Amundsen and Robert Scott (for whom the South Pole base is named) planted their flags here just a month apart. It's definitely quite cold here, but my first impression of the place upon exiting our LC-130 was actually that the South Pole is remarkably flat. You can look out in any direction here — pick your favorite North — and literally see nothing but snow until you reach the horizon.

In one day here I've met some brilliant scientists, toured advanced labs and seen fascinating work, but unfortunately there isn't the time to cover it all now (it's coming, though, don't worry). That's because our favorite Antarctic event — the boomerang — reared its ugly head again when poor visibility prevented our return flight from landing.

So I spent the night at the South Pole.

Remember, the term "night" doesn't mean quite the same thing here as it does further North, because the sun never sets in the Antarctic summer. But midnight was still a quiet, serene time to be here. While most people were asleep, I threw on my cold weather gear and trekked a few hundred meters from my barracks-style living quarters to the geographic pole, a modest marker in the snow maybe 75 meters from the more glamorous ceremonial pole, which is the usual spot for a photo op. For about 20 minutes, I had the entire world beneath my feet as the southernmost human on the planet, a rare and surreal experience that allowed me to appreciate my fortune in making it this far. Though the world literally revolved around me for those few minutes, it was a time to think of others, of the people who made this journey possible and got me to the bottom of the world.

More South Pole science to come, once we reach McMurdo later today.

Images: At the ceremonial (above) and geographic (right) south pole

Posted by Alex Witze on January 11, 2010
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Posted on behalf of Chaz Firestone

After two days at McMurdo Station, we leave tomorrow for the South Pole, home of the new South Pole Telescope (SPT), which saw its first light in 2007. But before we head over there, I had the chance to speak with John Carlstrom, an astrophysicist at the University of Chicago who leads a research team at the SPT. We'll hear from Carlstrom again later, but for now he offered a taste of the work his team is doing there:

The story of the Big Bang — and the cosmic microwave background radiation (CMBR) that is today a relic of that fateful explosion — will be well known to many readers, but the use of this radiation to detect galaxy clusters may not be. The CMBR has a wavelength in the millimeters to centimeters range and is often called the "afterglow" of the Big Bang, as scientists can study it to learn what the universe was like in its infancy. But like any light, the CMBR is also capable of casting shadows (or, rather, being obstructed to create a shadow), which is how the SPT uses it to detect clusters of galaxies.

Most of the time, light travels about the universe unperturbed, but when it passes through a mass of high-energy electrons, it can be distorted. In the vast expanse of space, galaxy clusters are hotbeds for this scattering of light, as they are essentially breeding grounds for the plasma that contains these ionized particles. So when the CMBR passes through a galaxy cluster, intra-cluster plasma distorts it, a phenomenon known as the Sunyaev-Zel'dovich (SZ) effect.

It was hypothesized some time ago that the SZ effect could be used to detect galaxy clusters, which would show up as "shadows" in the CMBR from the point of view of an earthbound telescope. In 2008, the South Pole Telescope swept the sky for CMBR and found these shadows, becoming the first telescope to use the SZ effect to detect galaxy clusters when it found four clusters, three of which had not been previously detected.

Conditions at the South Pole are ripe for this kind of astronomy. The atmosphere is thin at the Pole, where the altitude is 3,000 metres (10,000 feet), and because the sun is absent from the sky in the winter, the atmosphere there isn't churned up on 24-hour cycles like it is at other parts of the planet. The extremely low temperatures also limit the amount of water vapor in the air, which reduced signal disruption. And if you think you could just make a similar telescope at the North Pole, think again — that pole is over water.

The SPT has so far surveyed 800 square degrees of the sky and will have surveyed 2,000 square degrees by 2011. The ultimate goal of the current project is to survey to 4,000 square degrees, which would be about a fifth of the area visible from the South Pole (the entire sky is 40,000 square degrees, but you can only see half the sky from the South Pole). Carlstrom said they expect to find hundreds and thousands of clusters that no one has ever seen.

Hopefully we'll get to see the SPT tomorrow.

Image: Glenn Zorpette, of IEEE, interviewing John Carlstrom

Posted by Alex Witze on January 10, 2010
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Posted on behalf of Chaz Firestone

New arrivals to McMurdo undergo a grueling field training process affectionately called "Happy Camper Training," which involves spending the night in a tent camped out on sea ice. But due to the brevity of our visit to Antarctica, we didn't have time to spend the night, so our training session today was bumped down a notch to "Happy Picnic Training."

Still, we got our money's worth from the training session. When pitching a tent in Antarctica, you can't simply drive a peg into the ground to anchor your tent's fly, because snow is looser and thinner than land and the peg would jump out of the anchoring hole in a heavy wind. So instead, Antarctic tent-pitchers use a method called "burying a deadman."

To bury a deadman, dig a trench about half a meter deep, wrap the fly's strings around the peg, toss the peg into the hole, cover the hole with snow and stomp on the "grave" until it's compact. If you've done it properly and laid the peg horizontally in your trench (instead of vertically like a regular tent anchor), even strong winds won't be enough to rip the peg out of the snow. Another way to guard against the wind is to build a wall of snow bricks, which you can quarry from the snow by sawing out cubes and lifting them out with a shovel. Constructing the wall outside the door to your tent shields you from harsh winds that threaten to blow your tent away.

During a lunch break, we were joined by a skua (Stercorarius antarctica), the Antarctic equivalent of an American pigeon, at least behaviorally. Skuas (right) are the curious nuisances of the sky here, and though they're not quite as common as pigeons, they are just as desperate for whatever scraps of food a wandering human may have. This is actually a problem in Antarctica, where environmental protection is a high priority: McMurdo residents are careful not affect the natural balance of life here, and the rule of thumb is that "if an animal reacts to your behaviour, you're too close."

After lunch, we finished our training about two hours ahead of schedule, so our field training specialist used the extra time to give us a treat. We all hopped into the Hägglund snow and ice vehicle that we had used to get to the sea ice and drove an hour away from our spot on the McMurdo Sound to a more remote location on Ross Island. He called this spot "the room with a view," and told us that staffers are occasionally brought there on "morale trips."

When we exited the Hägglund, we could see why: We emerged in the middle of a field of snow and ice extending miles in each direction, with a thick white haze percolating around us, veiling a view of distant mountains (right). The sun occasionally peeked through the overcast sky, but for most of the time we just stood there, intimately enveloped by the continent. One other journalist and I suggested we all try a moment of silence, and when the group agreed, we witnessed the most acute absence of sound imaginable. In the middle of that deafening silence, it almost felt as if we were not supposed to see what we were seeing, and that somehow we had snuck through a back door and ended up with a view kept secret to the rest of the world.

Hopefully the camera does some kind of justice to the pristine beauty of this site.

Posted by Alex Witze on January 10, 2010
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Posted on behalf of Chaz Firestone

It took three nights, two delays and one boomerang, but we've finally reached Antarctica. Touching down on the ice runway at Pegasus Field was the smoothest landing I've experienced, but that should come as no surprise: Once the doors opened and we stepped outside, we could see flat ice for miles in every direction.

It takes only a few hours on the continent to understand how strange and beautiful a place this is. The sun never sets here, but just spins around the sky, casting gorgeous shadows on the distant mountains. I've taken many photographs already, but there is something odd going on here visually that the lens can't seem to capture. The horizon appears to wrap 360 degrees around you, the way it might if you were on a small island and saw ocean in every direction. And the landscape is so uniform and textureless for miles on end that it is difficult to estimate distances. On the way from the airfield to McMurdo Station, our home for the next two days, we spotted what seemed like a small foothill, until we saw an ant-sized climber on the summit. It became clear that the hill, which seemed near and petite, was actually much farther and taller than we had thought.

Mactown, as some of the veterans call McMurdo, has the feel of a small mining village, but the insides of buildings look like they might be on a college or high school campus. It has a fire department, a medical facility and a large cafeteria with buffet-style dining (though dinner tonight was steak and cod, a step up from dorm food at my college). The quaintness of the community disappears, though, when one beholds the vast vista of ice stretching out for miles from the base, which might as well be the set of some science-fiction film on a frozen alien world.

But we have little time to get used to life here. Though many people spend most of the summer season on the base, we have only two days, one of which will be spent in an intensive field training course to prepare for our journey to the West Antarctica Ice Sheet (WAIS) Divide. If weather keeps us stuck there, we'll have to camp out in tents in a cold, snowy, windy area that is remote even by Antarctic standards. After spending another day at McMurdo (Sunday is the one-day weekend here), we'll take a trip to the South Pole station, and then after that we'll hop on helicopters to the Dry Valleys, which, said one passenger on our flight down here, "make the Grand Canyon look like a ditch." Last is the trip to the WAIS Divide, and then, weather permitting, back to New Zealand.

It's a whirlwind tour of the continent, but I'll make sure to stop every now and then to take it all in — and of course share whatever I can.

Posted by Alex Witze on January 08, 2010
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Astronomers have found the second smallest exoplanet, HD156668b, a so-called "super-Earth" that's just four times the mass of the Earth. With an orbit of just 4.6 days (compare that to Mercury's 88-day orbit), this planet would not be a nice place for life. Yet, that such a small planet can be duly reported at AAS amid shoulder shrugging by the scientists and press alike shows just how far the exoplanet field has come in a few years.

The week of AAS began with discoveries from Kepler, and its search for transiting planets. And now it's ending (or at least my blog posts are ending) with this discovery, which comes from astronomers using the twin 10-metre Keck telescopes in Hawaii to look for the wobble caused by the planet on its parent star.

The two bookends show not only the race between the space-based and ground-based observatories, but also the different approaches they use: transits, which give planet diameter, and the wobble searches, which give mass.

But as much as the two groups are competing, they also need each other. Not just to confirm planets -- there are many false positives out there -- but also to get both size and mass so that density can be calculated. Density, it turns out, is the crucial measurement that will tell us whether these distant worlds are puffed up and full of gas, buoyant and watery, or hard as rock. For now, all we know about HD156668b is that it is damn hot.
Image: L. Calcada

Posted by Eric Hand on January 07, 2010
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It's no surprise that people do the best job conceptualizing the spatial and temporal scales of the everyday -- the length of a car; the length of a work day -- and have a much harder time with extreme scales, like the age of the universe.
But people are slightly worse at understanding extreme scales of time than space, according to Aaron Price of Tufts University, who gave a neat astronomy education talk on Wednesday.
In a survey of more than 400 undergraduates, Price found that students consistently underestimated big time scales and overestimated the duration of the quickest phenomena -- worse than they did for spatial scales. But in both situations, Price says, the mind is trying to condense the two extremes towards something more manageable in the middle -- which suggests that mental number lines are inherently logarithmic.

Posted by Eric Hand on January 06, 2010
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Anyone want some time on a really big telescope? Gemini, the observatory with twin 8-metre telescopes in Hawaii and Chile, could use the money.
In November, the UK cemented its decision to withdraw as a 25% partner from the six-nation observatory by the end of 2012. This is just one of many cuts Britain is making as the STFC tries to climb out of budget hole. The UK had flirted with maintaining some time in the northern hemisphere (since it already has access to ESO telescopes in Chile), but the Gemini board nixed that.
At a town hall meeting at AAS, Gemini director Doug Simons discussed his plans to carry on. Instead of dealing with a sudden drop at the end of 2012, the observatory is cutting budgets by 7% to 10% each of the next three years.
“2010 may be the biggest budget that we have for a very long time,” he said. “I do not expect Gemini to be the same observatory at the end of this process.”
He says the most savings will come from altering the science operations – which may diminish the custom ways in which the observatory manages its science queue.
But Simons is still hopeful that Gemini, which provides the vast majority of large-diameter telescope time for US astronomers through NOAO, will remain relevant. Five new instruments are nearly finished, and Simons wants to keep its unique capabilities in the infrared.

Posted by Eric Hand on January 06, 2010
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