IceBite Blog: University Valley
McMurdo Station, a major Antarctic research base, is like a small town. During the summer there are over a 1,000 people living there. About 200 people “winter over,” preparing everything for the next summer season.
Credit: M. Marinova
NASA’s IceBite project will spend three austral summers in Antarctica testing ice-penetrating drills for a future mission to Mars. A team of seven scientists recently returned from the first field season, installing scientific probes in the ice and frozen ground, and scouting for sites where the drills will be tested the following year. One of the team members, Margarita Marinova, wrote a blog of the team’s activities. In this third set of entries, she describes the team’s return from Lake Joyce to McMurdo Station, and work at a second field site, University Valley.
Dec. 1, 2009. McMurdo Station
Back in McMurdo after a productive and fun week at Lake Joyce, now we have only 2 days to get everything organized and packed for our second field site: University Valley. At Lake Joyce we could use the camp infrastructure that was already set up by Dale Andersen and his team, but at University Valley we need to bring absolutely everything ourselves. Food tent, work tent, chairs, tables, stove, water, food, pots & pans – everything we will need for 10 days. It is surprisingly hard to think of everything you will need for 10 days of science and exploration. Something as simple as not having the right pliers or screwdriver could put a serious damper on our science. But we also have to be careful not to bring too much – helicopter flight hours are precious, and we already expect that we’ll need three helicopter loads to get set up.
Because University Valley will also be much colder, we need to adjust some of our thinking to deal with that. For example, we’ll bring out as much water with us as we can. This is because out in the field we will have to melt snow for any extra water we need, and this is very energy and time expensive. We are also keeping track of all the items that we can’t allow to freeze – chemicals, liquids in glass bottles, personal items. All of these items need to be put into a “warm box” as soon as we get there. On the other hand, all the frozen food we’re bringing we can just toss anywhere and not really worry about it.
Well I’m off to get everything ready and lugging heavy boxes! University Valley, here we come
Dec. 7, 2009. University Valley
University Valley (elevation: 1677 meters, about 1 mile) is our second field site for the season. This is one of the most Mars-like places on Earth! It’s cold and dry, and mostly lifeless. And that’s why we are here: by studying this Mars analogue on Earth, we can better understand what’s happening on Mars. We are here to study the subsurface ice table, look at the biology and how and where it survives, and also to explore this little-studied valley.
University Valley with the snowpack at the head of the valley. Note the little bits of remaining snow: the amount of snow on the ground is greatest near the snowpack and decreases towards the mouth of the valley.
Credit: M. Marinova
University Valley is more than a kilometer higher than Lake Joyce, which makes it about 10°C (18°F) colder, giving a temperature of about -13°C (8°F) throughout the day. And that’s in summer! When the sun is shining it is nice and pleasant, but with wind the cold can quickly become painful. University Valley rarely sees air temperatures above freezing. So while at Lake Joyce we had to be careful about falling into the lake moat that had been melted by the day’s warm temperatures, at University Valley we can only get water for drinking by melting snow!
At University Valley our main goals are to set up a weather station, map the depth from the ground surface to the ice-cemented ground, explore the area to understand its geology and history better, and collect ice, snow, and dirt samples for isotope, biology and chemistry analyses. Setting up a weather station to record weather data year-round is a direct way of understanding a system. While we can make pretty good guesses at what the overall weather patterns are like, the details can be very important.
An example of how small differences can be very important is the “degree days above zero”: the number of degrees the temperature climbs above freezing (0°C) multiplied by the amount of time that the temperature is above zero. Even a few degree days above zero – such as at Lake Joyce – can cause widespread melting of surface and subsurface ice, changing the distribution of ice dramatically over a very short period of time. In theory, University Valley sees no degree days above freezing, but no-one knows for sure. If the temperature were to rise above zero, surface runoff would recharge subsurface reservoirs tens or hundreds of times faster than would the common process of vapor diffusion, in which molecules of water vapor in the atmosphere diffuse down through the soil and freeze. This is why are setting up sensors to collect a multi-year, year-round record of the weather conditions, so we can understand the processes that create the type of permafrost we see there.
An interesting feature at University Valley is the change in depth to ice-cemented permafrost ground along the valley floor. Permafrost is commonly defined as soil whose temperature never gets above freezing. In most places around the world, permafrost soil is cemented by ice: water melted at the soil surface trickles down into the pores of the permafrost soil and fills them. As the water freezes, the soil becomes ice-cemented. The term “cemented” is quite appropriate, as this soil is incredibly hard.
Jen Heldmann taking a core of the large snowpack. This is a completely manual process of twisting a big tube (with cutters on the bottom) into the ice. The depth of our core was about a meter (3-4 ft).
Credit: M. Marinova
In University Valley, however, because of the exceptionally dry atmosphere and the lack of surface melting due to the cold, there is a dry permafrost layer and then an ice-cemented permafrost layer below it. As the name suggests, the dry permafrost layer is soil – no ice – that never gets to temperatures above freezing. There is an ice-cemented layer below the dry permafrost layer, because with time even the tiny amounts of moisture in the atmosphere will make their way (diffuse) into the subsurface and freeze, molecule by molecule.
At University Valley we see an interesting gradient: the depth to the ice-cemented ground increases with the distance from the snowpack at the head of the valley. We think this relationship results from the most snow collecting at the head of the valley, and less and less snow collecting on the ground with distance from the snowpack. Snow on the ground acts as an accelerant for putting water molecules in the subsurface; thus prolonged or more frequent snow cover means more ice in the subsurface and so a shallower depth to the ice-cemented ground. After digging numerous pits, we have shown that this trend of ice-cemented ground depth increasing with distance from the snowpack is quite robust. (And after digging the many, many pits, dinner tasted incredibly good!)
With any extreme environment, studying the biology of the area can give us many insights into what the limits of life are and how biology evolved. The limits of life are of special interest since they tell us about whether Earth-like life could survive on other planets. If Earth life could survive there, then it’s more reasonable to think that alien life forms could have developed, or even still be surviving, on these planets.
Because of the great similarity of University Valley to Mars, understanding the biology here is of special interest to studying the Red Planet. We are collecting many samples to bring back with us to look for how many and what kinds of organisms are present in the soil. During one of our evening discussions, I learned that some organisms can be alive in temperatures down to about -10°C (15°F)! This may seem crazy since every organism needs liquid water to live! But these organisms have learned how to use slight changes in the bonding structure between the “frozen” water molecules to help them treat the cold water molecules as being liquid. It’s incredible how life figures out how to do this!
Another fascinating adaptation of biology is endoliths: these are organisms which live in rocks! Sandstone rock is very porous, so algae and fungi can squeeze inside (in this case the algae and fungi form a mutually beneficial, or symbiotic, relationship). The rock provides a good habitat because rock surfaces get much warmer than the air temperature (think of how hot the sand on a beach is on a sunny day), which helps the organisms stay warm and metabolize. In addition, the porous nature of the rock causes water to be sucked in and trapped in its pores, providing a nice supply to the organisms. And the icing on the cake is that the layer of overlying rock shields the organisms from the damaging UV of sunlight but lets enough light through for the algae to photosynthesize.
Now it’s time for another hot chocolate and then off to the super comfy sleeping bag