Ground Truth

The turquoise-blue color of Station Lake, a small lake perched above the northwest shore of Laguna Negra, is an indication that it is rich in sediment, and possibly biological nutrients, making it a target of scientific interest. Credit: Nathalie Cabrol

by Henry Bortman

PLL has been moved to its summer home on the northwest finger of Laguna Negra.

Meanwhile, back on the south shore, Jeff Moersch, an assistant professor of Earth and planetary sciences at the University of Tennessee, and his graduate student, Robert Jacobsen, arrived at PLL Base Camp today and began work characterizing the geology of the Laguna Negra basin.

Jeff and Robert are conducting two sets of experiments. One is ground-truthing, or verifying, mineralogical data collected by orbiting satellites.

Robert Jacobsen takes an infrared spectrum of a large boulder near PLL Base Camp. The spectrometer is in his backpack; the computer in front of him displays and stores the data the spectrometer records. Credit: Henry Bortman

The Andes are among the most geologically active regions on Earth. The landscape is continually pushed upward and twisted by the pressure of tectonic plates, and volcanoes explode frequently, sometimes with catastrophic results. These processes, as well as rain and snow wearing away rock and turning it to sediment, have heavily reworked the terrain.

A number of orbiting satellites have crisscrossed the Earth, recording infrared spectra that can reveal what types of rocks are present in which locations. Different types of minerals absorb infrared light at different combinations of frequencies, and it is these absorption patterns that orbiting satellites record.

Satellites in orbit, however, have to do their observing through the Earth’s atmosphere, which can distort their results. Jeff and Robert brought with them a portable infrared spectrometer, an instrument that does the same thing as the spectrometers onboard a satellite, but that can be carried in a backpack. By walking up to various types of rocks and recording infrared spectra up-close, without the interference of the atmosphere, they can obtain what is known as “ground-truth” data. Taking these ground measurements in a few locations will enable them to calculate the distortions caused by the atmosphere and to subtract the atmospheric effect from spectral maps of the entire region to get a more accurate picture of precisely what types of mineral combinations are present.

Jeff Moersch squints at the heat maps of the Laguna Negra terrain produced by his thermal imager, carefully jotting down in his field notebook information about where the imager is pointed. Credit: Henry Bortman

That, in turn, will provide background information for other PLL team members interested in understanding precisely what types of minerals are being washed down from the mountains that surround Laguna Negra into the lake, and by extension, what types of nutrients are – and are not – available to the organisms that live in the lake.

Their second experiment involves a thermal camera. This, too, sees in the infrared, but rather than looking at spectral data at small points on individual rocks, the thermal camera takes a picture of the heat being radiated by large areas of the landscape. Jeff and Robert set the camera up at PLL Base Camp, pointed toward a distant shore of the lake and portions of the surrounding mountains, and plan to record a series of images over a period of a few days.

What they’re interested in is not so much any one individual image, but rather how the “heat map” recorded by their imager changes during the course of the day. The entire landscape heats up during the day, under intense sun that sends us all running for sunscreen (and bemoaning the lack of shade). But different materials retain or lose their heat in very different ways during the cold nights. Large boulders, for example, retain more heat than small grains of sand. Similarly, wet ground retains more heat than drier terrain.

The thermal imager thus can create maps that show how materials of different sizes have been sorted, or separated out, by glacial action and by the movement of water on the surface. That information, in turn, can provide an understanding of how water and ice have moved through the landscape in the past, and how it is behaving today.

The geologic information from these two experiments will provide a foundation for understanding how the Laguna Negra basin’s ecosystem is evolving in the present period of rapid deglaciation. It may also help planetary scientists interpret images of the geologic remains of past periods of deglaciation on Mars.

PLL’s New Home

Liam (r) prepares one of PLL’s 140-pound anchors for deployment. With him (l to r) are Cristian, Trey and Chris. Credit: XenoQuest Media

by Henry Bortman

The Planetary Lake Lander has been moored for the past week a short distance off the southern shore of Laguna Negra, near PLL Base Camp. Its proximity to camp enabled engineers to test its data-sampling and communications equipment. And to easily get out to the device to fix whatever annoying problems – miswired connections, transmission glitches – cropped up.

Now that the exciting world of the northwest shore has been explored and found to be a scientific wonderland, however, the time has come to relocate. A decision was made a couple of days ago to move PLL to a spot just off the northwest shore, where the waters of Victoria’s Cascade tumble into the lake, bringing with them nutrient-rich glacial sediments. This location will provide very different information than the crystal-clear, and nutrient-poor, waters near Base Camp.

Liam (standing) and Trey sail PLL toward the northwest finger of Laguna Negra. Credit: Chris Haberle

The spot chosen offered a finely tuned mix of characteristics. There was the glacial melt water, of course, fantastic for science. But there was also, conveniently, a pair of underwater landslides, discovered during Chris Haberle’s bathymetric survey of the area. That was good for anchoring PLL so it stays put for the next three months. And to top it off, the arc of the sun across the sky lined up nicely with PLL’s solar panels, so there will be no worry the scientific equipment will run short on power.

Yesterday, Trey and Liam, along with Chris and Cristian, spent the day preparing PLL for its journey to and installation in its new home. That meant, first, moving it from its temporary home to Launch Point, on the lake’s southwest shore. The advantage of working at Launch Point is that it’s the one spot along the lakeshore accessible by road.

The scientific and communications equipment had already been checked and double-checked. What remained to be done was outfitting PLL with new anchors. Two 140-pound anchors. These were too heavy to lift, so they had to be disassembled, carried onto the PLL’s pontoon in pieces, and then reassembled. While moored off the southern shore of the lake, PLL has been held in place by relatively lightweight anchors, but for it’s longer-term stay on the northwest shore, it needs to be anchored more securely.

The Planetary Lake Lander moored in its summer home off the northwest shore of Laguna Negra. In the lower left, the waters of Victoria’s Cascade. Credit: Chris Haberle

Assembling the anchors was only step one. Liam spent most of the day yesterday “flaking” the ropes attached to the anchors. This is not a problem the average person has to be concerned with, but when you’re floating on the surface of deep, hypothermia-inducing water, on a moderately unstable platform, and planning to drop overboard a pair of 140-pound anchors attached to very long ropes, it’s a good idea to prepare carefully.

You might think the best approach would be to coil the rope in a cute little circular pile. Turns out, that’s not the case. As you may have experienced with a garden hose, what appears to be neatly coiled, when pulled on, can suddenly become hopelessly tangled.

That’s not such a big problem when you’re dealing with a garden hose. But when you’re dealing with a long rope, with a 140-pound weight attached to one end, and when you are about to send that weight hurtling down through 45 meters of water, you want the rope to play out smoothly, not to snag on anything. Such as a piece of expensive equipment. Or someone’s ankle. Because whatever it snags on will (a) probably get broken; and (b) be dragged down into the deep with little hope of recovery.

So you flake the rope. Which means you stack it up in what looks like a random back-and-forth pile, but a pile that, crucially, is snag-resistant. And then you flake the other rope. And then you go back and flake the first rope again, just to be sure. And then the second rope, again. And a third time, to be really, really sure.

All this flaking was time well spent. Today, the PLL was sailed to its new location, the ropes were deployed without incident, and PLL was secured for its three-month stay in the northwest waters of Laguna Negra.

It was after that that the problem occurred. When PLL engineers pulled out their ruggedized, work-anywhere laptop to “talk” to the equipment onboard the lander, they couldn’t establish communication. That was confusing. And annoying. Here they were standing right next to the device they were trying to communicate with, a device they had communicated with successfully from the Robo Dome only the day before, and suddenly a communications link that had been working perfectly had gone awry.

Long story short: when the laptop had been in the Robo Dome, it had been attached to an external monitor. And the window for the software package that talked to PLL had been displayed on that external monitor. But out on the water, there was only the laptop. No external monitor. You’d think the software could figure that out and display the window in question on the laptop screen. But if you thought that, you’d be wrong. Instead, all it could do was issue a cryptic error message. Fortunately, once the team got back to the Robo Dome and reattached the external monitor, communication was re-established.

Now that everything’s working as it should, PLL is set to spend the next three months collecting data and transmitting it back to the IRG group at NASA Ames Research Center in Moffett Field, California. At that point, some members of the PLL team will retrieve the device and ship it back to Ames, where it will get upgraded with both new hardware and new software, before being brought back to Laguna Negra next summer.

The data that it sends back will form the basis for the development of the first version of PLL’s autonomous control software. Developing that autonomous software is the primary technology goal of the PLL ASTEP (Astrobiology Science and Technology for Exploring Planets) project. It’s not yet clear how “smart” the software will be in Year 2 of the project. Ultimately, the goal is to program PLL to make decisions on its own about what events are of scientific interest and about how best to study those events. But in Year 2, it may not implement autonomous decisions, but rather limit itself to performing the analysis that would lead to such decisions.

Dawn

The domes of PLL Base Camp, still in shadow, while across the lake Cerro Echaurren catches early morning light. Credit: Henry Bortman

by Henry Bortman

Most mornings I wake up around 5:30, when night is just beginning to fade into day. With the tent zipped shut for warmth, I hear dawn coming before I see it. It starts with a bird that sounds like a cross between a crow and a duck. Two short blasts. If I were writing a symphony of daybreak at Laguna Negra, I would score it with a coronet. It echoes off the mountains that surround the lake. This is always the first sound of the day. Two or three of these birds call back and forth to each other.

Soon after, other birds join in, a chorus of woodwind sounds – flute, piccolo, clarinet, each with a different song. Every morning starts this way: the coronet call, followed by the woodwinds. And every morning I consider getting up to watch the dawn; then change my mind and snuggle back down into my sleeping bag. I can always go out and see it tomorrow.

But today I get up, put on my warm clothes, unzip the tent, and step outside. The world is still, as if suspended for a moment between darkness and the return of light.

I head east, toward the hills of rock rubble one has to traverse to get the best view of Meson Alto, the high peak to the east of camp. This is the peak that glows pink, peach blush, dried cranberry, merlot at sunset. In the morning, it puts on a different show.

Meson Alto, with an assist from rare morning clouds, announces the imminent arrival of sunlight. Credit: Henry Bortman

I’m high up above Laguna Negra now. I can see the domes and tents of our campsite. No one else is awake yet. Lizards dart behind rocks. A rabbit hops across my path. Birds watch me approach, eyeing me suspiciously, flying off a short distance when I get too close. They’re still singing, but not as persistently as they were earlier.

I continue climbing, reaching the top of the ridge on the east side of camp. From here there is a better view of Meson Alto and the other mountains to its south, but if I want to see them in their full glory, I will have to cross a large boulder-strewn field to another ridge. There’s always another ridge.

From here I can see the vast extent of the boulder field, which stretches down to our campsite – in fact, we’re camped within it. The boulders are the terminal moraine of the glacier that carved out Laguna Negra. From up here on the ridge, I can sense the tremendous expanse of terrain covered by the glacier, thousands of years ago, as it scoured out the 300-foot-deep bowl that is now filled with water; I can hear the ancient glacier, grinding away at the rock, pushing boulders ahead of it in its path as it flows down from Cerro Echuarren, where what remains of the glacier sits today.

Cerro Echaurren is just beginning to be lit by sunlight now. It is nearly white light, with just a hint of yellow. Other peaks in the area block the sun from lighting up the scene with the deeper colors of early morning. I stop to sit on a rock and watch the light creep down the mountain, down onto the glacier, down toward the water.

It’s calm this morning, even more so than usual, but not perfectly calm. The lake is not a mirror. Rather, as the peaks light up, long shimmering streaks of reflected light stretch out from the base of the mountains across the lake toward me.

I sit cross-legged on a large, flat rock, straighten my spine, breathe. I get lost in the flickering light on the lake. I’m still in shadow, in the chill of night, because the sun has not yet risen above the rim of Meson Alto.

As the nearly full moon sets in the west, early light on Cerro Echaurren is reflected on the still water of Laguna Negra.

I get up, walk around a bit, searching for a path to the next ridge to the east, so that I can get a full view of Meson Alto, but I don’t see any way to get there without having to do a lot of boulder-hopping. Most places, there are paths between the boulders, but here I don’t see a way. I decide not to make the attempt. I’m by myself, and proceeding east would put me out of line of sight of the camp.

I feel mixed about not achieving this goal. It’s something I’ve been wanting to do since I got here. Other people have made the trek and come back, reporting on the incredible view. But not today.

I start to head back toward camp. Every couple of minutes I stop and look back at Meson Alto, to see if it has started its morning light show. It puts on two shows each day, one at sunset, when it glows, the other when the sun is about to crest each morning.

The morning show is beginning. A bright white line of light rims its jagged, slanting summit. Rays begin to shine through the ragged rim, upward and out to the sides. As the sun gets closer to cresting the rim, the rays shift and grow. Then, just before the edge of the sun appears, the rays contract and become fuzzier, less distinct.

The first bright flash of sun breaks through between two small jagged mountain teeth. Within a minute, the entire sun is above the rim of Meson Alto. The hillside where I’m standing on the trail is now flooded with light. The temperature shifts from chill to warm. I unzip my down jacket, take off my scarf and gloves.

I make my way down the hillside into camp, now full of activity. It’s eight o’clock. Breakfast is waiting.

Note: The photos below aren’t from the morning described above. I decided to watch dawn light up the landscape that morning without looking through a viewfinder. Here are some images from other days, when I was out with my camera.