The Blue Ice Drill (BID) is a large-diameter agile drill system designed by the Ice Drilling Design and Operations group of the University of Wisconsin–Madison to quickly core-clean 241 mm diameter ice samples from near-surface sites. It consists of a down-hole motor/gear reducer rotating a coring cutter and core barrel inside an outer barrel for efficient cuttings transport in solid ice. A variable-frequency drive and custom control box regulates electrical power to the drill. Torque reaction is accomplished on the surface via handles attached to a torsion stem. Core recovery is achieved with either core dogs in the sonde or with a separate core recovery tool. All down-hole tools are suspended on a collapsible tripod via ropes running on a capstan winch. The BID is operated by a minimum of two people and has been used successfully during two seasons of coring on a blue ice area of Taylor Glacier, Antarctica. An updated version of the drill system, BID-Deep, has been designed to recover cores to depths up to 200 m.

The cone penetration test has been successfully used to classify soil for ∼100 years. However, it has received only limited contemporary use in frozen geomaterials. The historical and contemporary use of the cone penetration test in various frozen geomaterials is considered here and contemporary data from recent work in polar snow are examined. It is probable that many material physical properties (e.g. density, strength and microstructure) can be obtained directly from cone penetration testing. It appears under-utilized as a contemporary scientific and engineering investigative tool in frozen geomaterials.

On 1 December 2011 the West Antarctic Ice Sheet (WAIS) Divide ice-core project reached its final depth of 3405 m. The WAIS Divide ice core is not only the longest US ice core to date, but is also the highest-quality deep ice core, including ice from the brittle ice zone, that the US has ever recovered. The methods used at WAIS Divide to handle and log the drilled ice, the procedures used to safely retrograde the ice back to the US National Ice Core Laboratory (NICL) and the methods used to process and sample the ice at the NICL are described and discussed.

Many of the ice-coring objectives in the Ice Drilling Program Office (IDPO) Long Range Science Plan, such as those in the International Partnerships in Ice Core Sciences (IPICS) 2k array and 40k network, are attainable in many locations with an intermediate depth drill (IDD) that can collect core from a fluid-filled hole down to 1500 m depth. The Ice Drilling Design and Operations (IDDO) group has designed and is in the process of building an agile IDD to meet this objective. The drill tent, power distribution and core-processing systems are an integral part of the IDD, which can be deployed by small aircraft and assembled by hand to minimize logistic requirements. The new drill system will be ready for testing in Greenland beginning in late spring 2014. The first production drilling is scheduled for the 2014/15 field season at the South Pole.

Determining the expected age at a potential ice-core drilling site on a polar ice sheet generally depends on a combination of information from remote-sensing methods, estimates of current accumulation and modelling. This poses irreducible uncertainties in retrieving an undisturbed ice core of the desired age. Although recently perfected radar techniques will improve the picture of the ice sheet below future drilling sites, rapid prospective drillings could further increase the success of deep drilling projects. Here we design and explore a drilling system for a minimum-size rapid-access hole. The advantages of a small hole are the low demand for drilling fluid, low overall weight of the equipment, fast installing and de-installing and low costs. We show that, in theory, drilling of a 20 mm hole to a depth of 3000 m is possible in ∼4 days. First concepts have been realized and verified in the field. Both the drill cuttings and the hole itself can be used to characterize the properties of the ice sheet and its potential to provide a trustworthy palaeo-record. A candidate drilling site could be explored in ∼2 weeks, which would enable the characterization of several sites in one summer season.

A challenge for future deep-ice coring in central Antarctica is to identify an appropriate inert drilling fluid with no undesirable physical or chemical characteristics. The drilling fluids currently in use (kerosene-based fluids with density-increasing additives, ethanol and n-butyl acetate) are not intelligent choices for the future from safety, environmental and some technological standpoints. Recently proposed drilling fluids based upon ESTISOL™ have high viscosity at low temperatures, which severely limits their application in cold environments. This paper presents our research into the application of low-molecular-weight, fatty-acid esters (FAEs), substances commonly used in the fragrance and flavoring industries. According to available data, selected FAEs are not hazardous to human health. Considering density requirements alone, ethyl butyrate and n-propyl propionate best meet our present needs. The viscosities of these two chemicals are also the lowest among studied FAEs, not exceeding 4 mPas at temperatures down to −60°C. Both compounds are highly volatile, and insoluble in water. Such properties are attractive, but the applicability of FAEs to deep, cold, ice drilling can be evaluated only after field-based, practical experiments in test boreholes.

The 2011/12 Antarctic field season saw the first use of a new British Antarctic Survey (BAS) ice-shelf hot-water drill system on the Larsen C and George VI ice shelves. Delivering 90 L min−1 at 80°C, a total of five holes >30 cm in diameter at three locations were successfully drilled through almost 400 m of ice to provide access to the underlying ocean, including the first access beneath the Larsen C ice shelf. These access holes enabled the deployment of instruments to measure sea-water conductivity, temperature, depth and microstructure, the collection of water samples and up to 2.9 m long sediment cores, before long-term oceanographic moorings were deployed. The simple modular design allowed for Twin Otter aircraft deployment, rapid assembly and commissioning of the system, which proved highly reliable with minimal supervision. A number of novel solutions to various operational sub-ice-shelf profiling and mooring deployment issues were successfully employed through the hot-water drilled access holes to aid the positioning, recovery and deployment of instruments. With future activities now focusing on the Filchner–Ronne Ice Shelf, the drill has been upgraded from its current 500 m capability to 1000 m with additional drill hose and further generator, pumping and heating modules.

The NEEM deep ice-core drilling in northwest Greenland was completed in summer 2010 after three seasons, which included establishing all drilling infrastructure. Normal drilling operations in the main borehole were declared terminated at 2537.36 m below the surface, when further penetration was stopped by a stone embedded in the ice in the path of the drill head. The design and implementation of the drilling operation strongly resembled the NGRIP drilling program. The NEEM drill was an extended version of the Hans Tausen (HT) drill, with specific modifications to optimize its use with the highly viscous Estisol-240/Coasol drill fluid used at NEEM. Modification to the drill and its performance in the new drilling fluid was largely satisfactory and successful. Throughout the drilling, special consideration was given to the way chips were transported and collected in a new chip chamber, including the consequences of drilling a larger borehole diameter than with previous drill operations that used the HT family of drills. The problems normally associated with warm ice drilling near the base of an ice sheet were largely absent at NEEM.

Electromechanical auger core drills are widely used in shallow ice-coring practice on mountain glaciers and polar ice caps and sheets. Generally, these drills are lightweight, can be readily transported to remote drilling sites, are easily installed there and drill with relatively high rates of penetration and low power consumption. During the past few decades, dozens of electromechanical auger drills have been designed. However, the auger options were usually determined by experience, and the main parameters (auger angle and rotation speed) are varied in a wide range from drill to drill. In order to choose the optimal auger parameters, the discrete element method (DEM) is used to analyze the performance of cuttings transportation for different rotation speeds in the range 50–200 rpm and auger angles in the range 15–45°. To improve the efficiency of cuttings transportation, many factors have to be considered (e.g. particle sizes and their variability, ice temperature, material of the core barrel and jacket, and availability of needed driven motor-gears). For the conditions assumed in the present studies, the recommended rotation speed is 100 rpm at auger angles of 35–40°.

Maintaining ice-core quality through the brittle ice zone (BIZ) remains challenging for polar ice-core studies. At depth, increasing ice overburden pressurizes trapped air bubbles, causing fracture of cores upon exposure to atmospheric pressure. Fractured ice cores degrade analyses, reducing resolution and causing contamination. BIZ encounters at 18 sites across the Greenland, West and East Antarctic ice sheets are documented. The BIZ begins at a mean depth of 545 ± 162 m (1 standard deviation), extending to depths where ductile clathrate ice is reached: an average of 1132 ± 178 m depth. Ice ages in this zone vary with snow accumulation rate and ice thickness, beginning as young as 2 ka BP at Dye-3, Greenland, affecting ice >160 ka BP in age at Taylor Dome, Antarctica, and compromising up to 90% of retrieved samples at intermediate-depth sites. Effects of pressure and temperature on the BIZ are explored using modeled firn-column overburden pressure and borehole temperatures, revealing complex associations between firn densification and BIZ depth, and qualitatively supporting expected thinning of the BIZ at low ice temperatures due to shallower clathrate stability. Mitigating techniques for drilling, transport, sampling and analysis of brittle ice cores are also discussed.

The Institute of Low Temperature Science at Hokkaido University conducted ice-core drilling in alpine glaciers in the northern North Pacific region to reconstruct climate change in this region for the past few hundred years. We drilled two ice cores in the Kamchatka Peninsula, Russia. An ice core with a length of 211 m was drilled on a glacier at the summit caldera of Ushkovsky mountain in 1998. A second core, with a length of 115m (until bedrock was reached), was drilled on a glacier at the summit caldera of Ichinsky mountain in 2006. We drilled three further ice cores in Alaska, USA. Two ice cores with lengths of 50 and 212m were drilled on a glacier at the summit caldera of Mount Wrangell in 2003 and 2004. The third ice core was drilled on the ice divide among three glaciers, Black Rapids, Trident and Susitna glaciers, which represent a flat saddle north of Aurora Peak in the Alaska Range. This paper details the field operations and characteristics of the different ice-drilling systems used and the problems encountered.

The Chinese First Deep Ice-Core Drilling Project DK-1 has commenced at Kunlun station in the Dome A region, the highest plateau in Antarctica. During the first season, within the 28th Chinese National Antarctic Research Expedition (CHINARE) 2011/12 the pilot hole was drilled and reamed in order to install a 100 m deep fiberglass casing. In the next season, 29th CHINARE 2012/13, the deep ice-core drilling system was installed, and all the auxiliary equipment was connected and commissioned. After filling the hole with drilling fluid (n-butyl acetate), three runs of ‘wet’ ice-core drilling were carried out and a depth of 131.24 m was reached. Drilling to the bedrock at the target depth of ∼3100 m is planned to be completed during a further four seasons. We describe the work in progress and the status of equipment for the Dome A drilling project.

In deep ice-coring, as in many other disciplines, a winching system is involved in the overall operation of the drilling activities. The need to efficiently store the cable on the winch drum is well recognized, and the ‘orthocyclically wound’ approach is often used. This is accomplished by means of a ‘Lebus groove’, along with a level winding scheme of some description. The level wind is usually implemented in one of several ways using some mechanism to synchronize the position of the level wind with the point where the cable meets the winch drum. A novel method using a feedback control system is presented in this paper, introducing a virtually error-free approach to the surprisingly difficult task of level winding.

The IceCube Neutrino Observatory was constructed at the South Pole during the 2004/05 to 2010/11 austral summer seasons. IceCube transforms 1 km3 of Antarctic ice into an astrophysical particle detector composed of 86 cables (strings) of optical sensors buried deep beneath the surface. Each string required drilling a borehole ∼60 cm in diameter to a depth of 2500 m. The 5 MW Enhanced Hot Water Drill was designed and built specifically for this task, capable of producing the required boreholes at a rate of one hole per 48 hours. Hot-water drilling on this scale presented unique challenges and was rich in lessons learned, yielding a collection of notable developments and takeaways (e.g. fuel-saving measures, thermal modeling, firn drilling and closed-loop computer control). Descriptions of system functionality and of lessons learned from IceCube drilling are presented.

IceCube, a cubic-kilometer neutrino detector, was built at the South Pole using a hot-water drill system. Deep holes were drilled into the Antarctic ice sheet and filled with highly sensitive optical instrumentation. For the hot-water drilling, a computer model was developed to predict the hole sizes and hole lifetimes during construction. The goal was to predict ultimate size and freezeback rates based on water flow rate and temperature, drill speed, ice temperature and ream parameters (for a secondary operation where hot water continues to flow as the drill is withdrawn). This model proved to be very successful. It increased confidence that the holes would remain open long enough after drilling to allow the deployment of the necessary instrumentation. It also allowed for a decrease, over the course of the project, in the amount of overdrilling that was used as a margin against a too-rapid freeze-in. This resulted in significant fuel savings.

Electromechanical cable-suspended drilling technology is considered one of the most feasible methods for subglacial bedrock drilling. The outstanding feature of this technology is that the bit load produced by the drill weight is usually within the range 1.5–4 kN while the recommended load for diamond drilling is 10–30 kN or even more. Therefore, searching for the diamond bits that can drill in extremely hard formations with minimal load and acceptable rates of penetration and torque is the necessary step to prove the feasibility of electromechanical subglacial drilling technology. A special test stand has been designed and constructed to examine the impregnated, surface-set, toothed and specially manufactured bionic drill bits. The results of experiments with ten types of drill bits show that the toothed diamond drill bit has the highest penetration rate of 3.18 m h−1 in very hard and abrasive granite under a 3 kN load. The torque (28.7 Nm) and power consumption (1.5 kW) of toothed drill bits are acceptable for cable-suspended drilling. The penetration rates of bionic drill bits may also be considered suitable and fall within the range 1.0–1.69 m h−1 under the lowest tested load.

For ice-core drilling on high-elevation glaciers, lightweight and modular electromechanical (EM) drills are used to allow for transportation by porters or pack animals. However, application of EM drills is constrained to glaciers with temperatures well below the ice melting point. When drilling into temperate ice, liquid water accumulates in the borehole, hindering chip transport, filling the chip barrel and finally blocking the drill. Drilling into near-temperate ice is also problematic as pressure-induced melting can cause refreezing of meltwater on the drill which then easily gets stuck in the borehole. We developed a thermal drill compatible with the Fast Electromechanical Lightweight Ice Coring System (FELICS). The melting element consists of a coil heater, molded in an aluminum crown. Using the combined mechanical and thermal drill we obtained a 101 m surface-to-bedrock ice core from temperate Silvrettagletscher, Swiss Alps. The borehole with temperatures around 0°C was filled with meltwater. Power was supplied by two 2kW gasoline generators consuming a total of 70 L of alkylate fuel. Ice-core production rate was 1.8 mh−1. The drill produced non-fractured ice cores of excellent quality with a length of 70 cm and a diameter of 75–80 mm.

Supported by the US National Science Foundation, a new 1500 m, ∼40 ka old ice core will be recovered from South Pole during the 2014/15 and 2015/16 austral summer seasons using the new US intermediate-depth drill. The combination of low temperatures, relatively high accumulation rates and low impurity concentrations at South Pole will yield detailed records of ice chemistry and trace atmospheric gases. The South Pole ice core will provide a climate history record of a unique area of the East Antarctic plateau that is partly influenced by weather systems that cross the West Antarctic ice sheet. The ice at South Pole flows at ∼ 10ma−1 and the South Pole ice-core site is a significant distance from an ice divide. Therefore, ice recovered at depth originated progressively farther upstream of the coring site. New ground-penetrating radar collected over the drill site location shows no anthropogenic influence over the past ∼50 years or upper 15 m. Depth–age scale modeling results show consistent and plausible annual-layer thicknesses and accumulation rate histories, indicating that no significant stratigraphic disturbances exist in the upper 1500 m near the ice-core drill site.

The deep ice-sheet coring (DISC) drill was used for production ice-core drilling at WAIS Divide in Antarctica for six field seasons between 2007 and 2013. Continuous ice-core samples were obtained between the snow surface and 3405 m depth. During the 2012/13 austral summer, the DISC drill’s newly designed replicate ice-coring system was utilized to collect nearly 285m of additional high-quality core samples at depths of high scientific interest. Annual progress graphs are described, as well as milestones achieved over the course of the project. Drilling operations, challenges encountered, drill fluid usage, drilling results, and the drill crew’s experiences with the DISC drill and replicate coring system during production drilling are described and discussed in detail. Core-processing operations are described briefly, as well as the logistical undertaking of the DISC drill’s deployment to Antarctica.