Thursday, January 10, 2008

AGAP LPM installation

OK, so after getting all our gear together and staged for the two flights on Twin Otter aircraft, we finally winged off into the flat white expanse of the Antarctic plateau. Our destination was the Antarctic Gamburtsev Province (AGAP), which sits on the Gamburtsev mountain range that is completely submerged under the ice. It's about as high an altitude region as you can find in Antarctica, minus the peaks where the mountains actually protrude through the ice. The AGAP field camp is at about 11,500 ft above sea level, and the persistent low pressure system over the pole makes that feel like over 13,000 feet. Out on the plateau it is simply flat and white. The only terrain features are the wind-blown sastrugi, which can range from only a few inches tall to several feet. Around AGAP the sastrugi were all pretty small.

After about 2.25 hours flying time we finally hove the field camp into view, and it certainly was one of the most isolated places I've ever had the pleasure to visit.

On the ground there were only four semi-permanent structures and a number of tents in which the camp staff were living. We stowed our gear in the big yellow tent and grabbed some lunch with the locals once we got our gear off the plane. All in all we had about 2,400 pounds of gear, some of which came on the second flight later this afternoon.

The low-power magnetometer (LPM) had to be between 1/4 to 1/2-mile from the camp to prevent interference from people, vehicles, etc. We loaded up on snowmobiles and drug out most of the gear we had to install. Since it was high altitude and we had no time to acclimate the camp staff made us let them do all the digging of the vaults that our gear would be deployed into. This really sped along the installation process and let us try to figure out how to assemble all the components. The other science tech and I had only helped dig this out of the ice back at Pole, and hadn't gotten a chance to ever assemble/disassemble the LPM, so we were a bit nervous as to whether things would go together correctly. By the end of the day we had gotten all the components on the tower (solar panels, GPS antenna, Iridium communications antennae, etc.) assembled, raised the tower and stabilized it with dead men anchors, and installed the empty battery box and electronics boxes in the main vault. The trench for the sensor cable-about 60 feet long-had also been excavated, and we wired up all the connections it was possible to do at that time.

We called it quits at that point and retired to the camp to get some good dinner (salmon and halibut) and warm up a bit. The ambient temperature was right around -30F, and we were lucky not to have any wind whatsoever. It was a nice, cozy atmosphere in the galley tent, and I really enjoyed the conversation with the camp staff (about 10 folks, mostly carpenters there building the camp). Once everybody headed for bed and the generators were shut off it was the most silent place I've ever been. Seriously, with no breeze there was absolutely no sound, and walking out to the pee flag late that night it felt like my footsteps were screamingly loud and probably waking up the whole camp. Unfortunately, I couldn't sleep because I was really worried about how the complicated process of wiring the batteries and calibrating the LPM would go the next day.

We got an early start the next morning, and plowed right into getting our 800 pounds of batteries installed in the battery box down in the vault. This actually went more smoothly than I'd anticipated, and we completed it in about 90 minutes or so. Somehow I managed to do all this work without wearing gloves and not getting frost bite. Once we had the LPM totally ready to go we spent a long while talking on the Iridium phone trying to track down the right people back in the States, and eventually got the go-ahead to power up the system.

Unfortunately it didn't work the first or second times we did so. Eventually it was discovered that the 10 wires in a connector on the big cable that was what mated the magnetometer sensor to the electronics box in the vault had all been broken. This was pretty disheartening to say the least. I sat there in the snow uttering a few choice words for some time, but eventually removed the cable from the system and took it back to camp to repair. The camp mechanic proved to be a life saver, and after about an hour's work three of us managed to get the cable back together with the correct wires and pins in the connectors aligned correctly. We were still pretty cold, so grabbed some lunch and headed back out to the LPM site to put the cable back in and try once again to bring the system up. Thankfully it worked this time, and after maybe 5 minutes of calibrating the orientation of the magnetometer sensor we got the OK to seal the vaults and consider the LPM good to go for the next couple years. Feeling very much relieved, we called in to the camp and the staff came out and helped us cover everything with plywood sheets and snow.

We had postponed our flight back to Pole once the cable problem had been discovered, so once the LPM was found to be fixed we had the camp staff call back in and get the Twin Otter headed our way again. We got to chill out for about 2 hours, and eventually the drone of the plane's engines could be heard, so we headed out to the smallest airport I've ever flown in/out of (a pallet with 5 drums of fuel in the snow), loaded our gear, and headed back to the booming metropolis of South Pole Station.

So, despite the big hurdle to overcome with the broke cable we got to head home with a successful deep field experience under our belts. It was great to finally get this project taken care of after many delays and road blocks, and I have to say it is the most satisfying work experience I've had in my two seasons on the Ice. There was a lot of independence and trust given us science techs, and it was a big relief to be able to come through for all the folks that were counting on having this instrument gathering science data for the next several years.


AaroN said...

I followed this post in earnest anxious to complete reading so I could Google to discover the exact purpose of an LPM. I read a couple articles and was astonished to find the answers to several questions I had such as:
How do batteries perform at such low temperatures?
How much power is required to operate this equipment?
(Noting the solar panel) How do they overcome the lengthy dark season?

Excellent post!

EthanG said...

You may have found this all out already on your own:

The batteries are inside a whole lot of insulation and have a heater that is controlled by a thermistor to regulate their temperature.

I never saw any specs on power consumption in the limited documentation we were provided.

The solar panels are only used as long as there is enough solar flux to power the system. The power distribution unit switches over to primary battery power once external power input dips beneath a certain threshold.

I'm very glad to hear you are keeping tabs on me, and it was very much my pleasure (and relief) to get that cable problem fixed and come home successful. Catch you later!

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