Coring sediments in subglacial aquatic environments offers unique opportunities for research on paleo-environments and paleo-climates because it can provide data from periods even earlier than ice cores, as well as the overlying ice histories, interactions between ice and the water system, life forms in extreme habitats, sedimentology, and stratigraphy. However, retrieving sediment cores from a subglacial environment faces more difficulties than sediment coring in oceans and lakes, resulting in low yields from the most current subglacial sediment coring methods. The coring tools should pass through a hot water-drilled access borehole, then the water column, to reach the sediment layers. The access boreholes are size-limited by the hot water drilling tools and techniques. These holes are drilled through ice up to 3000–4000 m thick, with diameters ranging from 10–60 cm, and with a refreezing closure rate of up to 6 mm/h after being drilled. Several purpose-built streamline corers have been developed to pass through access boreholes and collect the sediment core. The main coring objectives are as follows: (i) To obtain undisturbed water–sediment cores, either singly or as multi-cores and (ii) to obtain long cores with minimal stratigraphic deformation. Subglacial sediment coring methods use similar tools to those used in lake and ocean coring. These methods include the following: Gravity coring, push coring, piston coring, hammer or percussion coring, vibrocoring, and composite methods. Several core length records have been attained by different coring methods, including a 290 cm percussion core from the sub-ice-shelf seafloor, a 400 cm piston core from the sub-ice-stream, and a 170 cm gravity core from a subglacial lake. There are also several undisturbed water–sediment cores that have been obtained by gravity corers or hammer corers. Most current coring tools are deployed by winch and cable facilities on the ice surface. There are three main limitations for obtaining long sediment cores which determines coring tool development, as follows: Hot-water borehole radial size restriction, the sedimentary structure, and the coring techniques. In this paper, we provide a general view on current developments in coring tools, including the working principles, corer characteristics, operational methods, coring site locations, field conditions, coring results, and possible technical improvements. Future prospects in corer design and development are also discussed.

Currently, hot-water drill systems are actively used to observe ocean cavities under ice shelves, detect the effects of climate change on glaciers, retrieve sub-ice seabed samples, study the internal ice structure with video imaging, log temperatures, measure deformations within ice, determine basal sliding velocity, provide clean access to subglacial lakes, and many other scientific applications. The main parameters of hot-water drilling systems in any configuration are flow rate, delivery pressure, and temperature of the delivered water. The controlled outcome variables are the diameter of the drilled borehole, rate of penetration, power and fuel consumption for ice melting, and refreezing rate of the borehole. The independent variables while drilling are the current/target depth and the temperature of the ice. The paper aims to present a design procedure for hot-water drilling parameters that are necessary to choose appropriate equipment and tools at the planning stage.

As a result of the severe natural environment with oxygen deficit in the Antarctic, using conventional manual work to screw and unscrew the drill pipe increases the labor intensity tremendously and causes an efficiency reduction. Therefore, it would be useful to design a clamper inside the drilling shelter, which could help to assemble and disassemble the ice core barrel with screw connection. This paper describes the design of and experiments with the clamper inside the movable drilling shelter. A related testing stand was also designed and built to experiment on relationships between the clamper motor current versus clamping torque and force. Through experimental data collation and calculation analysis, the following conclusions could be drawn: (1) according to the rotary ability of the Ice and Bedrock Electromechanical Drill (IBED) to calculate and determine the torque of clamper, the clamping torque required to provide by the clamper is 100 N·m; (2) finite element simulation and analysis of the non-standard transmission chain showed that the mechanical reliability of the subparts; (3) the experimental results showed the range of the clamping force and clamping torque of the clamper. The clamping force and clamping torque increased with the increase of clamper DC motor current, presenting proportional linear relationships. The clamper can meet the clamping requirements of IBED for screwing, unscrewing, and clamping, which will be greatly helpful when it is tested in the field.

China has made considerable efforts in its ice-drilling technology since the 1970s; however, a comprehensive overview of its achievements is still lacking. This paper reviews China’s progress in ice-drilling technology over the past five decades. First, drilling projects in the Third Pole and polar regions are summarized. In the Third Pole region, more than 120 boreholes have been drilled, with the deepest reaching 324 m and the highest on the summit of Mount Everest. In Antarctica, Chinese drilling activities have mainly been concentrated in the area near Great Wall Station and along the traverse from Zhongshan Station to Dome A. Key achievements include a >800 m deep ice-core borehole at Dome A, a 3413 m hot-water borehole at Qilin Subglacial Lake (QSL), and the recovery of two subglacial bedrock cores. Second, the mechanical and thermal ice drills developed in China are reviewed. Before the 2010s, China had only shallow-drilling systems. Since then, a series of ice drills with deep-drilling capabilities have been developed. Future drilling priorities include resuming deep coring at Dome A, exploring QSL, sampling the subglacial bedrock of the Gamburtsev Subglacial Mountains (GSMs), and expanding activities to West Antarctica. Simultaneously, existing drills that are still at the laboratory or early field-testing phase require further refinement and validation, and the development of new drills, such as a deep ice-core drill, a thermal ice coring drill, and a flexible-tube air reverse-circulation drill, should be actively pursued.