8 January, 1999

8 January


The explosives test pit at South Pole station is an area that is at least 20 feet deep and 50 feet in length. At the bottom of the

pit, tunnels are being blasted into its walls. They are practicing tunnel construction for the new South Pole station to be completed by 2005. John Wright (a.k.a. "Blaster"), patiently guided Ryan and I through the routine of a blast that could be felt 160 feet under- ground. We each were given the opportunity to set off a trial charge as we closed in on the proper combination of pentolite, blasting cap and detonator cord necessary to achieve the effect that we sought.

There were hydrophones (microphones) buried with the last string

of the telescope last season. We wanted to see if they were working properly from their icy perch on the cable more than a mile under the surface. By setting off a charge about 50 feet from the area of the last string deployed, we hoped to be able to get a response from the microphones. The real test would be on

Monday morning. We measured ice core remnants from the pit

where the actual test would be conducted to get an idea of ice density.

Checking the densiy of a fraction of the ice core removed from the pit that the explosion will occur in backs up our data on the calculated density. We'd like to know how fast the sound will travel through this ice.

Careful planning with the blasting cap and detonation cord ensures a safe and accurate result.

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