An efficient melting probe for glacial research

Abstract

In this paper, we present an electric-thermal drill with a novel design of a melting head that was developed within the EnEx-RANGE project. The design combines a short melting head with a large surface area of parabolic shape. It was succesfully tested in the laboratory as well as on Alpine glaciers (Langenferner and Mittelbergferner) and at the Ross Ice Shelf in Antarctica. In all these different environments, a high melting speed per specific power of typically 8.8 cm3 w−1 h−1 is achieved that is close to the ideal maximum bound of ~10.5–11.8 cm3 w−1 h−1 when neglecting all heat losses. It has also been demonstrated that the melting probe can be operated with typical equipment of small-scale field camps including a small power generator.

The Autonomous Pinger Unit of the Acoustic Navigation Network in EnEx-RANGE: an autonomous in-ice melting probe with acoustic instrumentation

“…The APUs were tested on several glaciers in the Alps and on the Ross Ice Shelf in Antarctica, an overview of these tests and the melting performance is discussed in Heinen and others (2021). The final field test of the EnEx-RANGE project was conducted in August 2018 on the Langenferner glacier in Lombardy, Italy, in collaboration with the Cybernetics Lab IMA & IfU of RWTH Aachen University, the University of Bremen (EnEx-CAUSE) 1 and the Technical University of Braunschweig (EnEx-MIE) 2 .…”

“…Similar to Enceladus, Europa's subglacial ocean is a possible habitat for life. The APU is the base for the development of a new melting probe, the TRIPLE-IceCraft (Heinen and others, 2021). The TRIPLE-IceCraft is a modular carrier system for transporting standardized payloads through several hundred meters of ice, penetrating into an ocean or subglacial lake and later returning to the surface.…”

“…The APU is a melting probe equipped with a powerful acoustic emitter and sensitive receivers. Its melting system utilizes heating cartridges in combination with a novel-shaped, high efficient melting head made from a copper alloy (Heinen and others, 2021). A data system with various auxiliary sensors is used to monitor the internal state of the APU and delivers input for position estimation.…”

“…Each heating cartridge is protected from overheating with a thermo switch and switches off at 100 ° C with a hysteresis of 30 ° C. The novel shape of the melting head was developed and a patent application filed during EnEx-RANGE and allows for an optimized heat flow (Linder and others, 2018). This results in a typical melting speed of v m = 3.5 m h −1 at a maximum power consumption of P max = 2400 W in-situ (Heinen and others, 2021). The 12 heating cartridges are organized in five groups such that the output power of the melting system can be increased in steps of 200 W. Each group is supplied with 230 VAC line voltage that is controlled by TRIACs located on the heater TRIAC ring including a compact driver circuit.…”

“…A freezing of the power cable or hull was not observed on alpine glaciers. For polar environments, where the melt water will wick into the firn, a special version of the APU was developed, where the sidewalls are equipped with heater foils and the power cable is covered in a water-repellent material (Heinen and others, 2021). For cold, water-filled holes a uncoiling of the cable from the inside of the probe is necessary in order to guarantee advancement, even if the melt channel is completely frozen.…”