2007 – 2008 US ITASE Field Report

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Travel Conditions

Figure 2 Change in elevation, temperature, wind speed and wind chill during the season.
Note increased wind speeds 8-11 Dec (days 40-43) and 20 Dec (day 52) resulting in two and
one days lost for research, respectively due to poor travel and drilling conditions.

Surface conditions over the traverse route varied from hard packed firn (first half of the route) to soft snow (second half of the route) with alternating regions of variable height  (cm to >1m) sastrugi.

Shift Schedule During Travel: During travel the team was divided up into two groups that operated as separate shifts.  Each shift required two Challenger 55 drivers, one Pisten Bulley driver, one crevasse detector operator, one shallow radar operator). The deep radar was operated by one person throughout the traverse (B. Welch). After some experimentation with number of shifts per day it was decided that a maximum of 3 shifts would operate per day, Shifts lasted nominally 3 waypoints (10km/waypoint) that averaged out to 4.5-5.5 hours per shift.  Following the day’s shifts the team stopped travel, rested for 8 hours, had a hot meal and then returned to travel.

Monitoring Team Member Fatigue: Pulse and oxygen saturation were measured every morning for every member of the team to assess acclimatization to field conditions.  Unfortunately the O²/pulse meter was not made available to US ITASE until several days into the field season so only one individual (who arrived later in the season) could be monitored from their season’s start to end.
Team average O² shows a decline with elevation within expected limits.  Team average pulse shows considerable variability over time. This variability can be ascribed to a combination of changing work and environmental conditions.

O²/pulse meters are inexpensive and easy to use.  They should be standard issue to field teams working at elevation.  Previous use by P. Mayewski in high altitude (>20,000’ ) environments has been invaluable in identifying individuals under stress and those likely to suffer from altitude effects.

Route reconnaissance: US ITASE has had considerable success in finding safe crevasse routes utilizing RADARSAT, Landsat and MODIS imagery (G. Hamilton and L. Stearns).  During the 2006-2007 season crevasse-like features were encountered several km from site 06-4.  Landsat imagery examined following this season revealed the location of these features.  Unfortunately Landsat imagery only extends to 82°S and this season’s traverse went from 80 to 90°S. The entire route south of 82°S was crevasse free except for one series of several en echelon crevasses (average width 50-100’) revealed during a Basler reconnaissance flight of the region from site 1 to site 3.  This fortunate finding allowed us to correct our route by a few km, sufficient to avoid the crevasses. While satellite imagery is an excellent tool for investigating traverse routes it should always be followed by aircraft reconnaissance. 

Environmental Spills: One incident occurred. A Challenger 55 radiator broke at winter–over site (06–4, long 144.6988309, lat 80.30768631) during season start–up resulting in one gallon of glycol spilled onto the snow surface.  All of the glycol was recovered with a spill kit and returned to McMurdo prior to departure of the traverse from the site.

Challenger 55s and Traverse Platform Configuration: One forklift–equipped, one plow–equipped; the same units used on previous US ITASE traverses. The plow unit pulled in a single line: one Lehman, one Polar Haven Berco, 3 Siglin sleds, and the Polar Pooper. The fork unit pulled in a single line: one Lehman, one Kitchen module mounted on a Berco, Blue Room (sleeping and science) mounted on a Berco, and the deep radar sled. Both 55s operated well this season although they are beginning to show wear.  The plow 55 has been in the field since 2000 and the fork since 2001.  Throughout phase one, the Challengers were almost new, but since their introduction to the field they have traveled ~8000 km with US ITASE and >1500km with LGT RPSC oversnow traverse. See “Mechanic’s Repair” section later on this report for details of repairs and the mechanic’s (Josh Swanson) recommendations.

Spreader Bars: Spreader bars were introduced to the traverse platform at the onset of the 2006–2007 season by the RPSC camp manager at that time. Spreader bar construction and related complications resulted in US ITASE losing several weeks of work.  The spreader bars were introduced to reduce sled drag by spreading out sled loads and by reducing re–use of sled tracks.  This system has apparently worked well for the SPIT traverse.  However, the SPIT traverse has operated largely over the Ross Ice Shelf and apparently does not use spreader bars on the plateau due to issues related to sastrugi (G. Blaisdell, pers. comm. 2007 US ITASE out brief). As it turns out spreader bars enhance sled torque in sastrugi regions and as demonstrated by US ITASE in 2006–2007 create unsafe conditions for individuals riding in modules towed on the ends of spreader bars in sastrugi fields. For the first half of the 2007–2008 season we configured one train in line and one utilizing a spreader bar primarily because the Siglin sleds were not equipped (as requested) with rear towbars.  Once we encountered softer snow (midway on the traverse) the in–line train performed well and the spreader bar train was repeatedly stuck requiring extrication by double–teaming the two Challengers. In addition following storms the spreader bars posed additional digging challenges because they are wider than the rest of the train. Further the spreader bar skiis were poorly constructed and they dug into the snow acting as anchors. In summation, the spreader bars wasted time at the onset of 2006–2007 and have served as little more than additional weight plus something extra to have to drag and deal with on traverse.  It is unfortunate that so much US ITASE time and effort was wasted on the spreader bars.

Pisten Bully (PB): As of 2006 the PB has served as lead vehicle for the traverse since it houses the crevasse radar.  The PB is highly maneuverable and has proven to be an excellent vehicle for the task. It was also excellent for conducting deep radar traverses around ice core sites. The mechanic’s report (later in this section) suggests that the PB be returned to McMurdo for overhaul this season.

Generators: Qty 2 diesel 12kw (primary camp energy supply, second unit for back-up) for heating of the kitchen and Blue Room plus powering the snow melter and the Eclipse drill plus other lesser uses (e.g. recharging batteries). Qty 1 gasoline 5kw (back–up power – never used). Qty 2 gasoline 2kw (primary use deep radar). Qty 1 gasoline 1kw (radar back up).

Use of the 12kw generators during the 2007-08 season reduced dependence on less safe systems such as propane and increased available power.  A make–shift chimney was built in the field to divert generator fumes from shelters.  This system requires upgrade.

Fuel Consumption:  AN8 usage for two Challenger 55s, one Pisten Bully, two 12kw generators.

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