Stormy Skies and Garden Worlds

Storm clouds that built up over Laguna Negra for several afternoons in a row sent the PLL team indoors. Credit: Henry Bortman

A team of scientists has traveled to remote Laguna Negra in the central Andes of Chile to test technologies that could one day be used to explore the lakes of Titan. The Planetary Lake Lander (PLL) project is led by Principal Investigator Nathalie Cabrol of the NASA Ames Research Center and the SETI Institute, and is funded by the NASA Astrobiology Science and Technology for Exploring Planets (ASTEP) program. This three-year field campaign will design and deploy a lake lander at Laguna Negra, which is a particularly vulnerable system where ice is melting at an accelerated rate. In addition to preparing us for Titan, the study will also help answer questions about how deglaciation affects life in glacial lakes. During the 2011 field campaign, Astrobiology Magazine’s Expeditions Editor, Henry Bortman, is providing a first-hand account of the team’s work through blogs and images.


Biology under Stormy Skies
Thursday, December 8, 2011

The weather has taken a turn toward the dramatic. For the first few days we were here, the sky was practically cloudless all day long. Then for a couple of days, puffy white clouds would build up in the afternoon.

Before the storms moved in, researchers collected samples and took measurements along the shore of Laguna Negra. Here Luis A. Rivas (l) monitors the temperature and other physico-chemical properties of the lake’s water. Commodore Chris Haberle has his hand on the tiller. Credit: Henry Bortman

But in the past couple of days, the afternoon sky has gone dark, we’ve heard thunder in the distance, and the peaks of the mountains that surround the lake have been obscured in mist.

And it snowed. Not down here in base camp. Here we got a half an hour or so of light rain. But up on Cerro Echaurren to the north and even more so on Meson Alto to the east, there are new dustings of white powder. That may not seem odd to those of you reading this in the northern hemisphere, where winter is approaching. But here below the Equator, we are only two weeks from the first day of summer.

Although some of us would prefer to sit on a rock overlooking the lake, listening to the wind and watching cloud formations roll through, the threat of thunderstorms has sent us scurrying to zip up the rain flies on our tents and has forced most of our activity indoors. It has also put a temporary halt to biological sampling on the lake.

But biologists are dedicated lot, and some members of the PLL team have plenty of samples, collected when the weather was better, that need to be filtered and prepared for laboratory analysis. This process involves sucking up water, liters and liters of water collected from Laguna Negra and Laguna Lo Encañado, into a syringe, some 50 milliliters at a time, and then forcing the water through a small circular filter laced with pores tiny enough to trap microbial cells.

In the biological dome, the collected samples are proccessed and analyzed. Here, Yolanda Blanco is sonicating the biological material trapped on one of the filters. Credit: Henry Bortman

The water gets discarded, except a small volume that will be use for measuring dissolved cations and anions. Also of interest is the yellowish-brown stain left behind on the filter paper, comprised largely of microorganisms from the lake.

Some of these filters are preserved in ethanol, for later DNA extraction. Other filters are kept on dry ice until they can be transported down to Santiago de Chile University, where they will be freeze-dried for the trip back to Madrid, Spain.

Madrid is where microbial ecologists Yolanda Blanco and Luis A. Rivas work, at the Centro de Astrobiología. They are part of a team that for the past several years has been developing a life-detection device, a device they hope will be sent one day to Mars, or perhaps to other worlds in our solar system, in search of evidence for extra-terrestrial life.

The device goes by the name SOLID (Signs Of LIfe Detector), which includes an antibody microarray in its sample analysis unit. This microarray crams hundreds of microscopic dots, each a distinct biological probe, onto a small glass slide. The dots, printed onto the slide, contain antibodies. Some of these antibodies react to specific types of organisms. Others react to common biological molecules, such as amino acids, the building blocks of proteins; or the lipids found in cell walls. Unlike past life-detection methods that look for biosignatures by heating a sample to high temperatures and sniffing at the released gases, the antibody-microarray approach is less destructive, more precise and capable of searching for hundreds of different biosignatures simultaneously.

The northwest “finger” of Laguna Negra can be seen near the center of this Goolge Earth image of the region. In the lower left, Laguna Lo Encañado is visible. Credit: Image ©2011 GeoEye/DigitalGlobe/Google; Data SIO/NOAA/U.S. Navy/NGA/GEBCO

The array is exposed to a sample, such as the material trapped by filtering water from Laguna Negra. If the organism or biomolecule that a particular antibody is designed to detect is present in the sample, the antibody binds to the sample material. This captured material is revealed by using a fluorescent probe. Examined under the right type of light, these fluorescent tags appear as glowing dots. The position of the dot on the glass slide tells researchers which organism or molecule has been detected.

Blanco, Rivas and their colleagues previously tested detectors at Rio Tinto, in Spain, and in Chile’s Atacama Desert, each time with a slightly different emphasis tuned to the environmental conditions of those field sites. One focus of the work at Laguna Negra will be looking for psychrophilic, or cold-loving, organisms.

The Garden World of the Northwest Shore
Posted on Friday, December 9, 2011

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.

Mariner 1 (the small red dot near the bottom center of the image) sets sail for Hangnail Cove, on the northwest shore of Laguna Negra, below the Echaurren glacier. Credit: Trey Smith

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.

Liam Pedersen, seated near the point where the thundering Victoria’s Cascade pours glacial water and sediment into Laguna Negra, conducts a promising test of communications between the lake’s northwest shore and PLL Base Camp on the south shore. Credit: Chris Haberle

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.

 

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