Today was focused on melting the horizontal chamber and on instrumentation. With the panel pulled from the vertical shaft there is time to look at the instruments that are used to measure the glacier's movement, The sensing instruments are the whole reason for going to this elaborate work! And it is a lot of work! Imagine having to fly all these scientists here, house them safely, feed them, provide electricity, let alone dig miles of tunnels through solid rock!
The melting process is just spraying hot water constantly over the ice. You can see in the pictures that the melting of the horizontal shaft has already progressed some ten feet into the ice. You can see on the bottom all the debris from the glacier. The idea is to continue melting forward and then take a sharp right into the vertical shaft. It will take several days of melting.
As the glacier moves down an incline it grinds rocks at the bottom, these scrape along the base in a specific direction. You can see the striations along the granite force plate that was located on top of the instrument panel. This rock plate was directly exposed to the glacier ice, it is made of a different material than the local granite and can withstand the constant grinding. If you look at the picture below you can see the scratch marks of the glacier this past year, they clearly show a direction. The sensors on board the panel include load cells and water pressure sensors. The load cells are attached in various ways. The researchers are interested in how much weight is above and more importantly how much horizontal drag there is. Imagine someone giving you a heavy book to hold. If I drag the book from your hands sideways you can figure out what direction it is pulled by placing a sensor on two adjacent sides. You can also weigh the book by placing a sensor in each hand.
Denis Cohen is a glacier researcher living in Geneva who is working with Prof Iverson. He joined us last night by hiking up to the tunnel and will stay a week. He plans on adding an instrument to the panel this year, he is interested in listening to the rocks as they slowly crack under pressure so he has brought along an acoustic microphone with an amplifier to listen to the pings of rock.
In the horizontal shaft the plan is to insert the new accelerometers. Once the melt is completed, the sensors will be inserted in a long tube. I spent most of the day preparing the battery packs for the accelerometers. This was just a lot of soldering to extend the battery life of the system. Once it is in the ice it must remain there, either transmitting wirelessly or through a cable, if the cable breaks the only way to get it back is to melt the ice next year.
Later that afternoon Hallgier goes skiing up and over to a small cabin above the glacier....and after dinner shows pictures to us all of his family and various ski trips... skiing and outdoor life is definitely a major part of Norweigian life. I realize that I have not been out of the tunnel for a couple of days now, so tomorrow it is time to see some sunlight.