by Henry Bortman
So far, our activities have focused on the waters along the southern shore of Laguna Negra, with occasional side trips to Laguna Lo Encañado to collect samples. But yesterday, for the first time, PLL team members Liam Pedersen and Chris Haberle struck out in the battery-powered Zodiac, Mariner 1, on a 40-minute, 4-kilometer journey to the northwest shore of the lake.
There, they discovered another world.
Laguna Negra is only 1.5 kilometers wide, but it is 6 kilometers long, the longer direction running north-south. The lake has two long “fingers” that stretch north, one to the northwest, the other to the northeast.
PLL Base Camp is situated at the center of the southern shore. The Echaurren glacier, however, sits high above the northwest finger. The team has been anxious to do research in this area, because it is where interaction between the glacier and the lake is likely to be greatest. That also makes it an ideal spot to consider as a summer home for the Planetary Lake Lander.
What a difference a few kilometers makes. Upon approaching the shoreline, the PLL advance team spotted underwater caves with denser vegetation than the scraggly assortment of plants along the southern shore. Then they saw the streams, lined with lush vegetation, and displays of wildflowers. And the massive waterfall, Victoria’s Cascade, named by the expedition that explored the area a century and a half ago.
Most importantly, though, from a scientific point of view, was the turbidity of the northwest water where the waterfall meets Laguna Negra. Most of the lake is crystal clear, which makes for lovely sightseeing, but an indication that the lake is nutrient-poor. As a result of global warming, the glacier in recent years has retreated to a great extent. There is no longer any direct contact between the glacier and the lake. And the water that spills down into the lake from the melting ice no longer carries much sediment. It is that sediment that makes lake waters cloudy. It is also that sediment that carries nutrients for life.
There is a small area on the northwest shore where this turbid water can be seen diffusing into the lake, but because it’s colder than the lake water, it quickly sinks to the bottom, mixing very little with the otherwise transparent lake.
It is just this interaction between the glacier and the lake, however, and the difference between this area, which can support a distinct ecosystem, and other parts of the lake, that makes it scientifically appealing – and a potential long-term site for the Planetary Lake Lander.
Fortunately, communications tests conducted between the northwest-shore landing site and PLL Base Camp were successful, making the prospect of situating the lake lander there for the summer even more promising.