Science! Yes, science is supposedly why we are all down here. Science. But what sort of science is happening on this cold, lonely continent? (And does it really justify our presence here?)
Today we had a personal tour of the Andrill (ANtarctic geologic DRILLing) Project, based out of the Crary Scientific Lab. The folks at Andrill are taking core samples of the sediment below the ice and water on the Ross Sea floor.
To put a dollar value on this project... we were told that it costs between 10-20 thousand dollars to recover each meter of core! Therefore, it will cost as much as $20 million this year!
the Andrill site, out on the Ice
note: all of the photos here are from Andrill's photo website
Andrill has been drilling for the past two years in two different locations. Last year the drilling operation was based on the permanent Ice Shelf, out past Scott Base, and sampled 1200 meters of sediment, the deepest core ever taken in Antarctica. This year, the drilling rig is twenty miles northwest of McMurdo on the seasonal Sea Ice. As of today, they have just passed the 1000 meter mark for sample, their goal for the season. This sediment is approximately 10 to 17 million years old.
The drill rig is similar to the ones that are found on boats, but it is modified to use the ice as the drilling platform. A hole is melted into the ice, and the bit is lowered through the water, approximately 1/4 mile, to the sea floor. They drill about 50 meters (170 feet) of core every day, cut it into 3 meter sections, label it (especially which side is up!) and send it back to McMurdo station via helicopter each night at 10pm.
the white tent protects the drill rig and drill operators from the elements
the drill rig inside
At this point, the sediment cores are placed into a refrigerator to regulate the temperature, so it doesn't freeze. If frozen, the water in the sediment would expand and shatter the cores!
typical core sample
Next, the cores are sliced in half length-wise with a water jet. One half is saved as an archive, and the other half is used for research. This half core, which is about 3" wide and subdivided into one meter lengths, is then photographed at a very high resolution in something that looks like a very long flatbed scanner. Preliminary chemical makeup is also analyzed.
cutting the core in half
After being run through the machines, the cores are moved into the laboratory, where they are visually inspected. The cores that we saw were mostly dark grey- like a chalkboard- and relatively uniform. They were hard to the touch, although we were told that they are pretty soft and can be crumbly in some instances. The scientists make systematic "cartoons" and notes about every inch of the core, recording things like rocks, worm holes, and shells that are found. All of these notes are entered into the computer, and linked to the photographs taken earlier.
the cores are laid into boxes for transport
the cores arrive at the lab
While we were there, Dave actually found a shell that was missed by the scientists! It was embedded perpendicularly to the cut face of the core, and created a crack in the core. He asked the Chris, one of the scientists, whether the crack might have been caused by the white squiggly thing in the sediment, and Chris picked up the end of the core and gave us a great view of the shell. They told him he gets a gold star and is now an honorary sediment geologist. Good eyes, Dave!
a scientist recording her visual inspection
The sediment is also analyzed under a microscope. Scrapings of the sediment are placed on a glass slide for this. At specifically interesting points, a thin sample can also be taken. For this, a slice of the rock is epoxied to a glass slide, and then planed down, or "lapped", to the thickness of a human hair!
At the end of all of this processing, the sediment cores are turned over to an entourage of waiting scientists. The samples will be used for current research as well as future research.
Relevance???
So whats the big deal about a bunch of sediment cylinders?
For one, they can give us an idea about historic trends in global warming. There have been cycles of warming and cooling of the earth in the past millions of years, and these cycles can be detected through the make-up of the sediment. If the core contains lots of glacial till, sand and rock sediment, or microbes, they can ascertain whether there was thick, thin, or no ice cover during that period, though they have little ability to place a time stamp on any length of core or how long it took to form.
Larry, our guide, described glacial ice using the "pancake batter" model: If you want your pancake to be larger, you add more batter to the center and the bulge pushes out the edges. Likewise, ice cover at sea level is an indicator of how thick the continental ice covering is. If the core suggests ice cover, scientists can extrapolate that the continent had heavier cover and global temps were lower during this period. They can further cross-reference this data with data on global temps from other sites around the globe to not only help date their samples, but to understand natural cycles and fluctuations of climate.
At this point, Larry got a bit fuzzy on specifics, but it was 3:30 am and we'd been gawking at him and his team for an hour and a half so we cut him loose and came to write it down because we love you!
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