The importance and role of Subglacial Antarctic Environments (SAE) is recognized as central to many processes that have shaped the polar ice sheets both today and in the past. Subglacial environments include a range of features that differ in geologic setting, age, evolutionary history, hydrological conditions and size. These environments are "natural" earth-bound macrocosms that in some instances trace their origins to a time before Antarctica became encased in ice. In contrast to other habitats, where solar energy is a primary influence, processes in subglacial environments are affected by the flow of the overlying ice, the ice-water boundary layer, basal heat flux and potential thermal or non-thermal fluid transfers, depending on the tectonic conditions. Recent findings suggest that a third control is subglacial hydrology, which enables the exchange of water and associated chemicals and sediments between subglacial systems; now known be viable life-habitats. The full spectrum of sub-ice environments present beneath the Antarctic continent provides an unparalleled opportunity to explore and study one of Earth's last frontiers and decipher fundamental earth and life processes. The exploration and study of subglacial environments will advance our understanding of how life, climate, and planetary history have combined to produce the Antarctic continent as we know it today.
The recent funding of three international campaigns to drill into and sample subglacial lake environments (Whillans Ice Stream Subglacial Access Research Drilling (WISSARD), the Lake Ellsworth Exploration and Lake Vostok Drilling Programmes) will result in a dramatic shift in the current understanding of Antarctic SAE via the generation of first time data on subglacial physical, chemical and biological processes. However, they are not an end point for Antarctic subglacial research and the need to maintain communications and coordination between participating groups during and subsequent to the drill phase of these projects is vital.
There is an emergent need to address two specific issues that are paramount as we move into a new era of Antarctic Subglacial Lake exploration. The first regards the development of SAE entry and sampling protocols that are commensurate with the need to protect these pristine and remote habitats. The second regards the technological developments that are required to ensure that there is maximum data return from current and future Antarctic subglacial missions. Many of the challenges for SAE exploration are technological. Currently funded lake access campaigns are largely oriented towards sample collection and return, with limited in situ analyses and little long-term monitoring of chemical and physical conditions. Part of this approach stems from concerns over environmental protection and the impact of deploying permanent instruments in lakes. However, the single largest factor limiting the acquisition of data using sensors and observatories is the current dearth of sensing technologies of sufficient maturity for deployment to the bed of the Antarctic Ice Sheet. Here, perennial cold, high pressure, low levels of target analytes, remote location and the need to deploy sensors via a borehole create severe challenges for instrumentation. Hence, there is currently a mismatch between the science goals and the status of technologies required to meet these objectives. While the first phase of funded lake access programmes will generate highly novel datasets and a revised understanding of SAE, a significant output from these campaigns will be the generation of new scientific questions and hypotheses that require a second phase of carefully targeted lake exploration. These follow-on drilling campaigns are already at the planning stage in some countries, but cannot be fully realized with the technology status quo.
SAE have been documented for some time using remote sensing geophysical techniques, but only very recently have plans been devised and implemented to sample and study these environments directly. The long lead in times for the sampling of these lakes is largely related to the technological difficulty of penetrating the overlying ice sheet, but also reflects the cautious approach warranted by the pristine nature of the environments, and their almost completely unknown capacity to sustain viable ecosystems. SCAR (e.g. via SALE) has played a fundamental role in shaping the science priorities and international partnerships in the nascent field of subglacial aquatic research, but now there is an important need for a new path forward that focuses international exchange on the appropriate technology and methodologies required to carry out the science in an environmentally responsible way. The goal of ATHENA Expert Group is to lay the foundations for future SAE exploration via the development of rate limiting Technological and Environmental infrastructure.