by Dr. Robert A. Bindschadler
"Practice Makes Perfect"
Our project took a major step forward in 2010, although the work we accomplished was completed far from the Pine Island area. Our goal was to conduct field work together for the first time, try out as many of our techniques as possible and test as much equipment as we could. I wanted to have the field team be the same people who would be first to return to Pine Island ice shelf in 2011-12.
Yup, that's right. 2011-12. It still seems like a long way off, but it is an incredibly complex operation to bring machinery as sophisticated as a helicopter to a harsh and remote site, so far from a warm hut and skilled mechanics. All that type of support has to be brought along. And the helos drink fuel at a rapid rate, if they are going to stay aloft, which we certainly want them to do! All this means that there is a mountain of camp supplies, tools, buildings and fuel to get out to PIG. That started this season with the caching of thousands of gallons of fuel at Byrd Station, in West Antarctica. The original Byrd Station (at 80S, 120W) was established during the International Geophysical Year in 1957-58 and since there there have been two other stations set up once the original was too completely buried. Now there is a 4th Byrd Station, still about 800 miles from McMurdo Station.
Next season, camp equipment will be added to this cache of fuel and the whole shebang pulled on sleds by heavy tractors to the desired Pine Island Helo Support Camp site. We've picked this site to be in an uncrevassed area just beside (south of) the crevassed ice shelf. From there we will be able to use helos to hop over to the ice shelf (and hop back!). The camp will be built as soon in 2011-12 as a construction crew can be flown in. Once built, it's time to call for the helos and then the scientists.
Back to our story of this season.
To practice, there was no need to travel far from the comfortable confines of McMurdo Station. There was a site similar to PIG, but uncrevassed, nestled in the elbow of Ross Island, around the corner from McMurdo. The area is called Windless Bight (which, of course, begs the question how windy it really is). Men of none other than Robert Falcon Scott's party named it and they knew wind, so we were hopeful for a pleasant field stay. We took only those items that we thought we would be using two seasons hence. This meant tents to sleep and eat in, and our scientific gear out in the cold, open air.
We knew from past measurements by other groups that the ice cover in Windless Bight is a floating ice at least 100 meters thick and that beneath there was deep water plunging many hundreds of meters to a distant sea floor. These conditions were close enough to the 600-m thick ice and 500-m deep water we expect on PIG to satisfy us. Before the main field party went out, Sridhar Anandakrishnan took his season's geophysics field team out to this area to practice how to collect seismic measurements of ice thickness and water depth by setting off small explosions and recording the reflected sound waves on "geophones". This was just the information we needed and it confirmed that the ice shelf was closer to 200 meters thick and the water at least 800 m deep. Perfect!
It can be surprising how much field gear is needed to do even simple tasks, and ours was a not-so-simple task. As we prepared in McMurdo in November 2009, the equipment pile reached ever higher in the final days and hours before it was stacked onto trailers and pulled out of McMurdo. It was slow going, but we only had about 20 kilometers to go and after an early morning start, everything and everybody arrived at Windless Bight by mid afternoon.
The transporters brought a forklift out and were so helpful. They could have just left our stuff in a big pile, but they worked with us to place every big, heavy item just where we wanted it. This was remarkably helpful and shortened our work by at least two days. They even brought 500 gallons of water to help us get our drilling water supply started and made a HUGE pile of snow right next to the reservoir pool (a common recreational swimming pool) to further simplify the tasks that lay ahead.
While the unloading proceeded, others set up camp and before they transportation crew left, we were able to thank them with our first camp supper.
With all due deference to Scott, Windless Bight is not without wind. Yet the weather was pleasant enough for Antarctica. More important, everyone got along extremely well and we discovered enough good cooks. My experience is that everyone works very hard in Antarctic field camps and this camp was no exception. In short order, we had the all the equipment unpacked a things were working.
The first big science task was to make a large hole through the ice shelf. This was accomplished with a hot-water drill. The technology is simple—melt snow, heat the water, pump it through a hose, point the hose down, and let out more hose as it melts its way through the ice—but it looks complex with hoses snaking all over, some carrying smelly diesel fuel, others carrying cold water and yet others carrying hot water. Martin Tuffer and Dale Pomraning from the University of Alaska-Fairbanks handled this task with help from the others when needed. They were happy to see that their new pump worked beautifully. When everything was purring along, it only took a little over an hour to make the first hole into the water cavity beneath the ice. We were on our way!
Larger holes were made by removing the initial drill hose and replacing the nozzle with more of a side-spraying "shower head"-like nozzle. This enlarged the first hole (about 2-3 inches in diameter) to 5-6 inches in diameter. This "reaming" was followed by a second reaming using an even larger diameter spraying nozzle to create a hole that was at least 8 inches in diameter (guaranteed by the 8-inch diameter ring set between the two water-spraying shower head cones on the nozzle. Drill rates were fast enough that the final hole was complete in a long day. This made us ready for the next step.
Alberto Behar of JPL was delayed getting to our field camp, and when he arrived the hole was approaching its final size. Alberto quickly set up half of the cook tent as his shop and before the hole was finished, he had his borehole camera system ready to go.
At this point the true story must take an unpleasant detour. As the hole was being prepared for the camera, some equipment was dislodged right next to the waiting hole and, as these things too-often go, the equipment (a scale used to measure the load on the drilling hose) slid ever-so-quickly to and down the hole! We attempted to recover the scale, but it had no sharp edges to snare. Next we tried to drill past it, but that also failed. Finally, we tried to melt a larger hole so that the scale would fall out the hole and into the water beneath: also to no avail.
Turning lemon into lemonade, we realized we now had something in the hole to look at and the camera system was put into action. Sure enough, we could see the scale wedged in the hole. It confirmed the improbability that we could us this hole. Fortunately, McMurdo was not far away and while most of us slept, two others spent the night driving into McMurdo to get more fuel so that a new hole could be drilled the next day. We consoled ourselves with the knowledge that this painful learning was one of the reasons we came here to practice and that we now would redesign some equipment and modify our procedures so that this could not happen at PIG, where extra fuel lies over 1000 miles away and might undermine success of an entire field season! So we were lucky, not clumsy, right?
Well practiced, the next day's hole went even smoother, no scale lost and before dinner, Alberto's camera was dropped into the new hole. We all huddled around the monitors in the tent. The "show" was about to begin. Not much was seen-at first. The water in the hole was made murky with the rust that came from the heaters. For 175 meters down, this was the story. Then the water became rapidly clearer, then crystal clear and we were all treated to a surreal view of the borehole wall, intricately scalloped by the reamer, spinning on the monitor screen as the camera spun in the hole, suspended by its connecting fiber optic cable.
What Alberto had added, and had yet to turn on, was a backward looking camera. This was important because one of our questions we wanted to answer with the camera system was how rough was the bottom of the ice shelf? The upward camera gave us a great view of this.
Not long after this came the biggest surprise of all. While we were staring at the camera's view of the hole, a large shape flashed by! Then to our universal delight, an orange "shrimp-like" animal swam into perfect focus. It frolicked in the borehole, perched on the cable and generally put on a show while all of us sat hypnotized in front of the monitor. How totally cool and totally unexpected! This video has become quite popular.
After we returned, I've learned quite a bit more about this creature from marine biologists. Stacy Kim of Moss Landing Marine Laboratory was the first biologist to see the video and immediately recognized it as a Lyssianasid amphipod. It was about 3 inches long and Stacy concluded that this meant there was quite an extensive biological community under the ice here—even so far (20 miles in our case) from open water.
After all the excitement subsided, the camera was lowered nearly a full kilometer down, but we did not reach the sea floor and very little else was seen—just the deep blackness of the water sub-ice environment. An additional biological tease appeared as the camera was reeled back in—not on the monitor, but on the cable itself. A tentacle was noticed attached to the cable as it returned to the surface. The sample was photographed, bagged and left with marine biologists in McMurdo. We still are waiting to tell what it was from.
A second slight detour from our smooth game plan occurred once the camera returned to the underside of the ice shelf. The upward looking camera showed that the cable had cut into the side of the bottom of the hole, preventing a smooth entry of the wide camera body into the large hole. After a couple of gradual tugs with the winch motor, Alberto took a heavier hand to the controls and ran the winch motor at full speed. We held our breath as we saw the icy barrier fill the monitor screen, then shake violently, but once the view stabilized, we saw that the camera had found its way back into the hole. Having almost lost the entire package (and possibly ruined another hole for the next experiment), we agreed not to "hang around" to see if our amphipod would return or if something else might appear and returned the camera to the surface with a "job well done".
This was certainly a lot of excitement for one day, but we had more work to do. It was now the turn of Tim Stanton and Jim Stockel to deploy the ocean profiler. This is the only profiler of its kind and was custom engineered and built for our project. During the days of drill setup, Tim and Jim and been meticulously preparing the profiler for its maiden voyage into the icy depths and it was ready to go once Alberto's camera was safely home.
As the lost scale had painfully taught us, it is hazardous working over a large hole that disappears into 200 meters of ice and yet more water beyond. This made the profiler deployment particularly nerve-wracking. We wouldn't be able to connect the profiler to the cable before both were already by the hole's gaping mouth. For the people charged with making this connection accident-free, anyone's movement was usually preceded by their announcing what they were going to do and others acknowledging that they understood. It may sound silly, but it wasn't when so much was at stake. There would be no "do-overs" with this one-of-a-kind instrument.
Sighs of relief were heard all around once we had guided the profiler into the hole and it was successfully held by its cable. Data began to spring onto the computer screen once it hit the water in the hole. The data continued to stream across as the profiler continued its deep journey. Safe deployment of the profiler required it to sit a the bottom of the heavily weighted cable for up to a day to allow any ice that may have formed on the instruments to gradually melt. A fascinating feature of the profiler system is that it transmits its data to a surface receiver that then automatically dials Tim's home computer in Monterey, California. So we could not take these calls in Monterey, but instead had to call Tim's associate to hear what had been phoned in by the profiler's surface companion.
All seemed fine with the first post-deployment profile. On-board the profiler, oil is pumped to bladders that change the units buoyancy, allowing it to rise or sink as it rolls along the cable. The first profile was just a few conservative meters and all seemed to check out. We were elated with our success and our additional discoveries. It didn't take long to pack up everything and return to the nearby McMurdo. Faster still was the final stage of returning our equipment and packing for the homebound flight.
It was at the threshold of this triumphal return that a call from Monterey interjected the third detour to our journey. The profiler had stopped sending data. The surface unit phoned, but no data was present. This was a wilting disappointment to us all, but particularly to Tim and Jim. They returned to our camp site, but there was little they could do. Now that we are all home, they are continuing to examine what might have gone wrong. Plans are already being made to return to McMurdo next season to conduct further tests, this time through sea ice, without the additional tasks of hot-water drilling through a thick ice shelf. The profiler has to work at PIG and, as our experience at Windless Bight showed, practice makes perfect.