Researchers used a mini-sub to motor around the subglacial Lake Whillans. The sub was equipped with a video camera and a fiber optic link to the surface. One of the big issues involved in probing these subglacial lakes is trying to do it without contaminating the lake with microcrobes from the surface. So presumably that was an issue here. The video, however, makes no mention of efforts to sterilize the mini-sub. Maybe the scientists just skipped the whole idea as being too much of a problem(!).  After all, they were way down in Antarctica, who would know?