Movin' Right Along

IceCube is definitely in full swing this season. We've completed the deep drilling and deployment of 6 strings and are deploying the 7th right now. We should be able to get at least one more before Christmas (maybe even two) and another two before the New Year. This is, of course, barring any unforseen mechanical or other system failure and, God forbid, any injuries.

Drilling usually takes about 27 to 36 hours for one hole. This is from the time that the drill head enters the ice (about 75 ft. below the surface of the snow or the "firn") to when the 60 ft., 1,000 lb weight stack is pulled from the hole and detached. The drill is comprised of 3 separate spools, sending 2 - 4 in. hoses and one 1 in. cable down the 2,500 meters (8,200 feet) to the bottom of our hole. The cable's job is twofold: it supplies communicatiosn to the drill head so we can "steer" it and read out the pressure and temperature of the water, thus being able to calculate the lifetime of the hole (how long it will stay open to stuff our instuments down it), it also has a kevlar type strength member to support our main drill hose. The other hose is a return water line to resupply the heater tanks and return hot high-pressure water to the drill head.

The cable is taped to the main hose with a high-tech very expensive fiber glass tape. This activiy provides two of the most boring jobs available as a driller. One is taping the cable to the hose on the way down and the other is cutting the tape off as the cable/hose comes up. Again, this is a 30 hr. process on average. Yesterday, since cableguyland is a little slow in between deployments, I volunteered to cut tape. It was a great experience and it helps me "bridge the gap" between drillers and non-drillers. After all, we're all IceCubers, right?

During my tenure as drill tape cutter, we found a section of hose (most sections are around 100 to 150 meters) that appeared to have been slipping out or through its strain relief. This is characteristic of a hose that is pulling or elongating, called "necking", which compromises the structural integrity of the hose. Once we removed the strain relief, we also found a couple of half-inch sized nics or cuts in the hose. These signs all pointed to a quick hose change, which takes less than an hour (practice makes perfect). All of this is important because this hose carries superheated water at very high pressures, something like 190 degrees F at 800 to 1,000 psi (pounds per square inch). Any abnormality in the hose or thinning of the walls can produce a catastrophic failure of the drill or a dangerous stream of water vapor.

This morning, after deployment is finished, I will head out to the deployment site and complete the deployment by doing the "cable drag". This involves paying out the rest of the deployment cable off of its spool, dragging it over out drill/deployment tower and mating it to the surface cable in the SJB. In all, this process takes less than an hour and in performed by 7 or 8 people.

Then I get to have brunch... the only thing that gets me out of bed on Sundays...

Good-bye for now.