Our GPS stations consist of a GPS antenna, solar panel, and a large black pelican case with all the electronics. These stations have recorded position every 30 seconds for the past few years, giving us a very detailed record of glacier motion. Unfortunately, the stations typically turn off in the winter months when there is no light to recharge the batteries, but they work roughly 2/3 of the time.
These stations were installed to better understand the impact of water reaching the bottom of the ice sheet. Water is denser than ice, so in certain places it can hydrofracture to the bottom of the ice sheet. When it reaches the bottom of the ice sheet, it can lubricate the ice-rock interface, reduce the friction, and cause enhanced slip (kind of like the impact of putting water on a slip-n-slide).
We call the places where the water hydrofractures to the bottom of the ice sheet "moulins". The above picture shows a stream flowing on the surface of an ice sheet. You might notice that the stream disappears into the ice. That's a moulin.
We collected roughly half of the GPS stations today and will pack them up for shipment tomorrow. The day after tomorrow we will head back up to the ice to collect the rest of the gear.
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