Responsible environmental stewardship for the exploration of subglacial aquatic environments requires investigations to progress from the least invasive techniques to more invasive ones in a stepwise manner. An iterative progression of investigations will generate scientific data while simultaneously providing important information to define standards and protocols that in turn may be refined based on newly acquired data. The ideal approach would be to characterize as many subglacial lake environments as possible using remote sensing and ground seismic sounding and then select examples of different types of environments for progressive investigation. Although the committee recognizes that the ideal approach may be difficult to implement, nonetheless, an incremental approach to and identification of future research sites are strongly suggested.

Once the decision is made to directly sample a particular subglacial aquatic environment, the committee believes that the biology of these environments needs to be protected and is therefore the first priority. Accordingly, good stewardship requires that the cleanest technologies practicable be employed during the exploration of these lakes, and that exploration does not permanently alter the biological and chemical nature of these environments (see Recommendations 7 and 8).

A simple first step would be collection of a water column profile (i.e., using in situ sensors on some kind of profiling package) and a small sample of the water. It is not necessary to sample the environment in its entirety during the initial stages of exploration, because the physical, chemical, and biological properties of the water column need to be understood before realistic standards for contamination can be set and required advancements in engineering for more advanced exploration can be determined. Key data to be acquired in the first step of this progressive approach would ideally be geared toward helping understand partition coefficients, mixing regimes, habitats that have the potential for microbiological activity, and the fate of contaminants. The simplest approach would involve a CTD cast with other sensors, followed by a vertical profile and sample return of water and surface sediment.

Although investigation of Lake Vostok is the most advanced, three other lakes (Concordia, Ellsworth, and South Pole) are under investigation or consideration. These lakes represent different categories based on their geologic characteristics. Vostok is a rift lake, Ellsworth and Concordia are basin lakes, and South Pole Lake may be small and shallow or may consist only of sediments and, therefore, not actually be a lake. The proximity of Vostok, Concordia, and South Pole lakes to existing research stations has great logistical benefits. Although Lake Ellsworth is not located near an existing research station, a reasonable case can also be made for a temporary drilling camp at Lake Ellsworth where a hot-water drill would penetrate the ice sheet in a few weeks (Box 1.2). This site is located along a crevasse-free path to the Patriot Hills, where a blue ice runway exists and supplies and personnel can be flown directly from Punta Arenas, Chile. These locations make the drilling easier to manage, strong environmental protocols more easily to apply, and the access for international inspection easier. These subglacial aquatic environments are thus good candidates for investigations based on logistical criteria.

Unfortunately, the basic hydrology of Lake Concordia and South Pole Lake is completely unknown, so the potential environmental impact of sampling these lakes on other subglacial aquatic environments in their respective drainage basins is also unknown. However, the basic hydrology of Lake Vostok and Lake Ellsworth is understood, and they appear to be good candidates for exploration.

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