Rothera to Cape Framnes cGPSNovember 27, 2012
Got the go ahead for deployment to Cape Framnes and Leppard Glacier cGPS sites. Will also support Daniel Farinotti’s deployment by carrying a half load of the required 2.5 plane loads of equipment and supplies to his Starbuck Glacier camp. We again had Ian Potten as our pilot and Roger Stilwell as GA, but substituted communications manager Adam Bradley for GA Ash Fusiarski since Ash is Daniel’s GA. We took off from Rothera at 9:10 a.m. and headed for Cape Framnes at the eastern tip of the Jason Peninsula which divides the Larsen B region, including the last remnant of the Larsen B Ice Shelf in Scar Inlet, from the still intact Larsen C Ice Shelf. The CAPF cGPS system needed a replacement of its GPS receiver.
We arrived at the cape at about 10:35 a.m. and quickly spotted the solar panels powering the system perched on a rocky ledge. Ian made a couple more circling passes to try to see if a small snow patch very close to the instrument would be usable as a landing site as opposed to the more obvious site about a mile away up a blue ice slope to a much larger flat, snowy plain. During one of the circles, Ian spotted a dark circular spot down just above the sea ice a few miles southwest of the instrument. He suspected it could have been a penguin colony, and as we approached it became clear that it was a breeding emperor penguin colony containing a few hundred adults and chicks.
Ian stayed a suitable distance and height above the colony to avoid stressing the birds, but close enough that we could obtain some photos that could be used to count the number of individual penguins. After a couple more passes, we finally landed at 11:15 a.m. at the more distant but safer site about a mile from the instrument. We donned ice axes and crampons and were able to cram all the necessary equipment and tools into our rucksacks and proceeded downhill toward the instrument. At first we tried staying on some sastrugi to the left of the shortest path to the instrument in order to minimize our passage over blue ice. But after I stepped through a couple of thin snow bridges over some unseen slots, Roger decided to take us back to the more direct blue ice path where we could more easily avoid the obvious narrow slots. Our crampons held us well on the sloping ice and we arrived at the instrument about an hour after leaving the plane. We took some quick photos and noted that the receiver appeared to be logging data. We swapped out the defective receiver for the replacement, and then ran some tests, one of which, namely the ethernet test, was failing.
At that point we called Seth White of UNAVCO who suggested we put back the original receiver. I started removing connectors, but noticed that I had apparently bent a pin on the new receiver when attaching the multi-pin ethernet connector to the receiver. I was able to bend the pin back, re-attach all the cables and rerun the tests. This time the ethernet test passed, so we closed up the box and called Seth again. He said everything now looked good, so we packed up and headed back to the plane, this time taking the more direct route staying on the blue ice all the way. After arriving in about half an hour, Ian informed us that Andy Barker had relayed him a message from Seth that he had erroneously told us that everything was working and that the receiver was not tracking satellites most likely due to the GPS antenna either not attached or not attached correctly. Turns out he had been looking at data logged before I had discovered the bent pin, and that I must have incorrectly seated the GPS antenna cable the second time. So after a quick snack we started back to the receiver. Upon opening the case we could see that the satellite tracking LED was not lit, so we must not have checked it after fixing the bent pin. I removed the GPS antenna cable from the receiver and carefully reattached it, noting that this time it seemed to take up more threads than when I removed it, so I must have had it cross-threaded. After powering up the receiver we noted that it was now tracking satellites, so we again closed up the box and called Seth. He said he was sure he was now looking at new data and that everything looked good. We climbed back up the ice hill, noting that a new lead had opened in the sea ice to our right since our previous ascent. We got back to the plane, packed up, and took off for Starbuck Glacier at 8:00 p.m. after just under nine hours on the ground. We landed at Daniel and Ash’s scenic Kilo camp on Starbuck at 8:35 pm, unloaded their final equipment, took a few photos, and were back in the air at 9:05 pm headed this time for the Leppard Glacier cGPS.
Our next stop at 9:40 pm was at Leppard Glacier, the site of another continuous GPS instrument. Ian was able to land just a few meters from the solar panels and antenna, so Roger and Adam were able to hop out of the plane and immediately started digging behind the panels. The goal was to uncover the box enclosing the electronics in order to copy some new firmware and a configuration file to the GPS receiver.
The box is almost identical to the one at Flask Glacier that we had visited three weeks earlier. The difference was that the box at Flask was buried under a couple of feet of loosely consolidated snow, whereas the box here at Leppard was under at least six feet of more firmly compacted snow (aka firn). After almost two hours of digging by Roger and Adam, they were down about 5.5 feet below the snow surface and still hadn’t reached the top of the box, let alone uncover its entire lid which would allow us to open it.
We also hadn’t yet exposed the bottom of the splices in the solar panel legs and associated cables, both covered in ice, that would allow us to raise the solar panels another couple of feet or about a year’s worth of accumulation at this apparently snowy site. So we decided to call it a day and head back to Rothera. We took off at 11:40 p.m. and arrived in Rothera at 1:00 a.m.