Andy Smith (BAS), Keith Nicholls (BAS), Tavi Murray (Leeds), Keith Makinson (BAS),
Gušfinna Ašalgeirsdóttir (Leeds)
Physical Sciences Division, British Antarctic Survey,
Cambridge CB3 0ET, and
School of Geography, University of Leeds, LS2 9JT
We report on preparations to access the bed of Rutford Ice
Stream, West Antarctica, during the 2004/05 austral summer. Holes will be
drilled to the bed using the BAS hot-water drill, used successfully many times
over the last 15 years and now upgraded to the required 2.5 km capability. We
plan to drill in two locations: first where the bed is believed to comprise
dilatant, deforming sediments; and second where the bed is non-deforming and
ice motion is by basal sliding. Sediment samples will be retrieved from the bed
using a gravity corer. Short sections of ice will also be collected at specific
target depths, using a hot-water corer. Tethered stakes (copies of the CalTech
design) will be inserted into the bed, to detect differential motion between
the basal ice and the bed. Instruments measuring water pressure, temperature,
tilt and orientation will be deployed in the boreholes. Sensor packages will
span the whole ice column but will be concentrated towards the bed. On the
surface there will be a combined network of GPS receivers and passive seismic
recording stations. These will be supplemented by seismic reflection and
shallow radar (GPR) surveys. Finally, we are in the process of arranging a
collaboration with NASA-JPL to enable their upgraded high-resolution video
camera to be deployed in the boreholes.
The project will contribute to a number of research areas,
including:
1. West Antarctic Ice Sheet history in the Weddell Sea
sector
2. Ice Stream basal processes and conditions
3. Ice Stream dynamics
Preparation for this project has already been underway for
more than 4 years. The field location is 1300 km from the main support base at
Rothera and everything must be input by Twin Otter. A depot containing 200 fuel
drums and approximately 15,000 kg of equipment (mostly for drilling) was
completed at the end of the 2003/04 season. A further 9,000 kg of equipment
will be deployed, along with up to 8 personnel, for the field project itself.