In all cases ice core diameters were small (4cm to 6cm), discountinuous and mainly broken. Little information is available on the analyses of these cores except for some BNSAE preliminary results on grain size, density and crystal orientation (V. Schytt, 1958), and on the Alaskan ice core where bubble volumes and airpressures were measured (H. Bader)
5) Slide 5 summarizes the beginning and extent of the pre-IGY and IGY core drilling projects preformed by SIPRE in Greenland and Antarctica between 1956-1959. The individual projects, dates of field activity, type of drill and final depths of core recovery are shown. All cores were obtained using a modified Failing-1500 drilling rig and cooled-compressed air to remove the chips. Twenty foot length (6.5m) of steel pipe stems were used to lower and raise mechanical drill. The core barrel recovered an average 2m long core. Lowering, raising and disconnecting the heavy pipe stems was an extremely time consuming procedure (R. Lange, J. Tedrow). In general core quality was fair, often broken, but reasonably continuous in 1956; the 1957 core was in much better physical condition and reached a final depths of 411m.
The same Failing-1500 drill and equipment was transported to Antarctica and used to successful core to 305m at Byrd Station in the austral summer of 1957/1958 and through the Ross Ice Shelf, Little America V at 264m in 1958/1959 (R. Patenaude, R. Ragle).
A new phase in ice core drilling began with the Camp Century, Greenland project (listed at the bottom of Slides 5). With the successes of the IGY projects behind them, SIPRE was encouraged to continue with their long-held goal to develop a deep ice core-drilling system capable of reaching bedrock depths and below. The subsequent plan received full approval of the National Scientific Advisory Committees and support of the NSF. In 1957, B. Lyle Hansen was charged with the formal responsibility of designing and building this new system. The feasibility of such a drill was a subject that Hansen and Bader had already considered when they were working together at the University of Minnesota in 1950 and 1951 (SIPRE moved to Wilmette, Illinois in 1952). At that time they had been focusing on using a thermally heated coring-drill to be operated in a fluid-filled hole to prevent hole closure. The difficulties associated with using heat to core into sub zero ice and remove the associated melt water were many and complicated. The mechanical drill used during the IGY operations, was developed as an expeditions solution for immediate IGY objectives. In 1957 Hansen and Bader reignited the thermal ice-coring concept and with the engineering assistance of H.Ueda, constructed a prototype system for the Camp Century project. The resulting winch-operated wireline-suspended thermal drill was field tested at Camp Century during 1960-1961. The initial field tests resulted in a 186m deep, 12 cm diameter core. The main problem using the thermal process was the induced alteration of the top 70m of firm core, caused by the heating element.
