South Pole Weekly Report, January 27, 2008

The drill head is put on a sled and then taken to Cargo for retro shipping immediately after the drilling of the last hole is completed.

Photo by Albrecht Karle

The 17th and 18th strings for the season were successfully drilled and deployed this week, meeting the season's "stretch goal" and also setting a new record for number of strings deployed in one season in spite a 5 day delay in the scheduled start to the season. Following a one-day break, drilling began for the 17th hole on January 21st. Drilling of the 18th hole began as deployment on the 17th hole was wrapping up on January 23rd and string deployment was completed on January 25th 5 days ahead of schedule. The table below provides the hole location and string installation completion dates for the holes planned for this season. The IceCube baseline plan was 14 strings with a stretch goal of 18.

The IceCube population at the end of the week is at 47. All cargo has been received that is scheduled to date. Retro cargo has begun in earnest in order to meet the northbound vessel in McMurdo.

Preparing the drill camp for winter began immediately after the drill came out of the 18th hole with the removal of water from the main hose reel, the return water hose reel and all surface hoses. In addition, the water tanks have been drained, all the water has been blown out of all the buildings in the Seasonal Equipment Site (SES) as well as all external hoses. The system has also been flushed with glycol. After the glycol is cleaned from the system all of the Do Not Freeze (DNF) items will be removed from all the buildings and the camp will be disassembled. This work will commence on Monday, after a 2 day weekend to give the drillers a break.

We have managed to retro all the heavy items, such as cable reels and drill cables, in time to meet the vessel in McMurdo. The firn drill is currently on the 3rd of next season's holes and we expect to finish hole 3 and 4 by Thursday before winterizing the drill. Next season's SES berm is completed and we expect to move the buildings to the new site by the end of next week.

The last DOM of the 18th string with deployment crew and drill lead.

Two logging runs were performed on the strings 53 and 54. The goal of these measurements was twofold. The first objective was to re-establish the logging device as a tool to measure the diameter of a hole in case we are concerned that the hole diameter might not be big enough. This can happen in case the data from the drill head are missing or inconclusive and any issues during the drilling give reason of doubt that the hole may not be big enough. A careful data analysis should allow determining the refreeze rate of the hole and that this data can be used to validate the refreeze models used to determine the IceCube drilling strategy.

A deep inclinometer and thermistor device was deployed to a depth of approximately 2537 meters on String 45. The device is reading near vertical with temperature in the expected range. With help from the cable team, the deployment team constructed extension support and electrical cables to take advantage of the deeper hole created by the drillers and the DOM target depth was increased to 2455 m. This makes three deployed inclinometers for the season. Once the devices reach near-ambient temperature, the winterovers can make the simple measurement to determine starting tilt. The deep thermistor will ultimately be useful for constraining the ice temperature profile and extrapolations to bedrock, which are relevant for the ice strain rate and the hotly debated frozen/liquid state of the South Pole lake.

Strings #54 and #45 passed Wet Connector Tesd (WCT) and Quad Connector Test (QCT) and will be connected to the hubs on Monday, Jan 28th. The final two bundles of patch cables were installed in the ICL and all but 3 strings are connected to the DOR cards.

IceCube Lab (ICL) winter storage was started in earnest this week by moving 134 DOMs into the ICL's first floor. DOM test cables and spare harnesses were also moved into the ICL. IceTop Freeze Control Units will likely be moved in the week of Jan 28 to Feb 3.

The 14 surface cables pulled into the ICL's west tower this season were marked with tape and buried this week. A plywood barrier was installed to allow for the following 26 cables to be installed into the remaining culverts. The snow was compacted and marked with flags.

This was the last DOM Testing week, as we wrapped up and stowed equipment. Holes 16 and 17 were filled with DOMs from the buffer, and hole 18 was mostly filled with DOMs from SPAT21 (South Pole Acceptance Test). The rest of the South Pole inventory for the next season looks like this: 36 IceTop DOMS and 122 InIce DOMs.

134 DOMs are stored for the winter in the ICL.

Photo by Mike Kleist

As the final string was deployed this week, we winterized the test site, took down the DOM testing tent and moved all unlucky DOMs that did not get the chance to be deployed this season to the ICL for winter storage. The South Pole Testers of DOMs can proudly say that 1,174 DOMs were tested this summer.

CBS returned to the South Pole for the first time in 10 years and interviewed several IceCubers. We are currently expected to appear on the CBS evening news some time between Feb 11 and Feb 13.

Michelangelo D'Agostino wrote an article on the new South Pole Station for "The Economist".

There were two reportable safety incidents this week:

In the first, a driller pulled a muscle in his back while reinstalling the clamshell collar on the TU20 winch. The collar weighs approximately 10 lbs. The driller was standing properly and not reaching. This was clearly an accident that could happen to anyone.

In the second incident, a driller suffered hot water burns on his wrist and hand while disconnecting a hose from the generator. The generator heat exchange system is connected by hoses to the EHWD water tanks. These hoses became frozen and showed no flow or temperature at the water tank end. The generator began to overheat causing residual water in its system to heat and pressurize. When the hose was removed at the generator this heated water was released causing the injury. An investigation is underway. The driller will heal fine.

The IceCube Pole team on Sunday, January 27, 2008.

Photo by John Jacobsen