Monday, August 1, 2011

ARIANNA 2010 Part 2: Arrival in Moore's Bay

Here is part 2 of the guest post by Jordan Hanson, about the 2010 ARIANNA field season.

The beauty which surrounded us during our helo flight to the detector can only be inadequately described. We flew past windswept mountains covered in dark weather, accompanied by white glistening glaciers beneath. We observed rock formations and islands in the ice shelf that protruded upwards for a thousand feet, such as Minna Bluff. Finally, we passed Mount Discovery and proceeded onto the vast, open Ross Ice Shelf – a flat expanse of pristine snow-covered sea ice over half a kilometer thick. One hundred and twenty kilometers from our departure point, we located our detector.

After we touched down and the rotors of the helo stopped spinning, we began to unload the gear and set up camp. First we established a “cargo line,” a row of bags and tents that allowed us to access individual pieces of equipment easily in an environment in which it can be difficult to maneuver. We also had to scan for crevasses, potentially melted cracks in the ice that can have depths of hundreds of feet. With the help of ground penetrating radar, we were able to trace out a safe area on which we could safely build our camp. I remember it being so windy (in excess of 40 mph from the south) that my hands got numb each time I took them out of my parka pocket to take a bite of my sandwich.

Once we had constructed camp, we began cooking and boiling water to keep warm and get used to living there for two weeks. We had several tents: one for working and the kitchen, three tents for sleeping (Steve, Rebekah, and myself), and a tent which served as an outhouse. We unpacked our scientific gear and began installing it in the work tent. After we created our camp site, it was my job to establish a 1 kilometer flag line to be used in a later experiment. I went with a mountaineer from McMurdo, who examined the output of a ground-penetrating radar unit while I pulled it on a sled. Placing a bamboo flag every 100 meters, we staked out a crevasse-free line 977 meters long. Camp looked like a few yellow dots on a vast, flat white surface, backed by mountains covered with glaciers in the background. After placing the flags, we headed back to base.

I was eager to fix the detector, which had not come online yet since the sun had returned to shine on our solar panels. We had a small wind generator during the previous season, but it turned out not to draw enough power from the wind storms that happen every so often on the ice shelf. Steve injured his back the day we arrived in camp, so he returned to McMurdo for medical treatment while Rebakah mangaged the camp and I saw to the ARIANNA prototype. I had a satellite phone which I used to communicate with Thorsten Stezelberger, who installed the detector originally with Spencer Klein in the 2009-10 season. I noticed that the 12V lead-acid gel battery used to power the detector was cracked, having slightly frozen and expanded. However, it still held charge, and thus we do not expect that this was the problem.

It took us a long time to excavate the electronics box, which was buried in six feet of snow, beneath the metal rig that supports the solar cells. Once we had it in the tent, I used a Honda generator and a DC power source to power the electronics, while I checked each electronics component individually to located the problems. Before replacing anything, I extracted the data from the previous season and saved it on one of our computers and in other places. There was brand new event data that we had never seen before, since our station ran even after the wireless communications were removed. I replaced the CPU battery backup, which had lost its charge after so many months without power and in -30 degrees Celsius temperatures. I replaced the CPU itself, which appeared to be non-functional, and the analogue to digital converter (ADC) as well. After I fixed those components, I checked to see if the Iridium satellite modem began to draw current. I eventually figured out that the network settings such as port assignments had been lost and/or changed for certain systems upon shutdown, and after fixing all of that, the satellite modem began sending data North. Fixing the current prototype was a big victory for us, because it allowed us to take data during the 2010-11 season at a lower threshold, since man-made noise sources from the wireless communications equipment had been found and eliminated. In addition, I built and installed a taller, more powerful wind generator that allowed us to take data further into the winter while the sun dipped below the horizon.

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