Science Requirements: Sonde for Retrieving a Basal Ice Core During Clean Hot Water Drilling

The IDP Science Advisory Board identified in the IDP Long Range Science Plan 2019-2029 a priority need to create the IDP Science Requirements for clean sample acquisition for a drill capable of fast retrieval of a core from sediment-laden basal ice. The need to retrieve basal ice samples in aqueous environments is important for a number of scientific applications, including biological studies and grounding zone assessments, where it is very likely that the basal ice will contain entrained sediment. It is envisioned that this ice coring sonde would be associated with a hot water drill tbd, for example the Roving or other drill. The sonde for the Cal Tech hot water ice coring drill designed by Englehardt, Kamb, Bolsey (J. Glaciol. 2000) may make a reasonable starting point for hot water ice coring sonde design, except that it is known that the core dogs in that drill were not functional in dirty ice. Furthermore, in deployment at both the Kamb Ice Stream (Caltech) and at the Whillans Ice Stream grounding zone (WISSARD-UCSC), slow advance of the drill head through sediment-laden ice led to an unacceptable degree of melting of the ice cylinder within the annulus. A different coring head and sonde design is needed, possibly including aspects of a rotary drill head. The logistical requirements associated with use of the sonde should be minimized such that the drill system should be useful in remote locations, and it should be compatible with clean access protocols for subglacial exploration (e.g. National Research Council, 2007). From discussions organized by IDP with iterative discussions between scientists, IDP engineers and IDP staff, the following are the science requirements for a Sonde for retrieving basal ice cores appropriate for use with Clean Hot Water Drill systems.