Lake Fryxell, Taylor Valley, Antarctica
by Peter SmithDecember 27, 2007 -
Heavy clouds, snow flurries, light winds and temperature near 20 F. With wind chill it feels like about 10 F and this is the warm part of the trip. Next week we fly to higher elevation where the temperatures should drop well below zero. Even so, the weather has prevented the helos from arriving to take us to Lake Vida in Victoria Valley. The pass above our camp leads to Wright Valley, the next one to the northwest, and it is completely cloud filled. Victoria is on the other side of Wright so until the weather lifts, there is little chance that we will go today. Fortunately, the experienced polar scientists of the group say that weather conditions can change rapidly and tomorrow is forecast to be better flying weather.
Our team is using the extra time to catch up on data analysis and various indoor activities. It is 9 a.m. now and if we do not get the signal to proceed with our daytrip plans by noon, then Doug plans to start another trench which takes 5 hours from camp to return. I will use this opportunity to tell the story of our experiences during the last few days in camp.
Chris McKay, Doug Ming, Sam Kounaves, and Susanne Douglass arrived at Lake Fryxell on December 20, at 9 a.m. They immediately decided to hike across the lake to see "if the other side was really there." Lake ice is several meters thick and easily survives the summer; however, the margins of the lake where the water is shallow melt back about 10 m from the shore. To reach the ice you can put on waders, take the rowboat, or run really fast.
Ice skating is not an option. The forces of wind, solar heating, and currents have pushed and shoved the ice into fairy castle structures and sharp ridges. There are pockets where ice has melted, then frozen over, not dangerous, but an unwelcome surprise when you step on one and find yourself in water up to your hip.
The other side of the lake is the site for the F6 camp and supports another team of scientists. The "stream team" uses this camp as a base to study the flow of water into the lake from the upper valleys and the two glaciers that bracket the lake: Commonwealth and Canada. On each stream they have constructed a weir, a partial dam, made from sand bags; it has a sluice positioned in the middle of known dimensions so that the stream flow can be measured.
Back at Camp Fryxell, there were 4 other microbiologists here already studying the life associated with the lakes and streams. Typically, they study bacterial communities, mosses, and the master of the valley—the mighty nematode. The species in these valleys are found no where else in the world. The nematode is a microscopic, worm-like animal that performs a constant St. Vitus dance, wriggling chaotically until it finds food or warmth. Partly, the warmth they seek comes from the opposite sex.
Most nematodes are sexual creatures, but some are parthenogenic. This wonderful word comes from ancient greek and means virgin birth. For instance, the Parthenon is the temple of the Virgin, in this case Athena, the virgin goddess of wisdom. One consequence of a virgin birth is that the child will always be female. Therefore, Jesus Christ, born of a virgin, required a miracle.
Our Phoenix IPY team (International Polar Year project led by PI Leslie Tamppari of JPL) is treating the valley like an alien planet. We attempt to duplicate the science activities that the Phoenix mission will perform on Mars. First, dig a trench down to the permafrost layer where the ice is hard as rock. Then sample the various strata that are revealed in the trench wall and analyze these samples using laboratory instruments to assess the chemistry, mineralogy, microscopy, and biology. The gradients of these measured quantities and the changes in character from layer to layer are used to reveal the history of the site. Our goal is to position trenches at several locations within the patterned ground characteristic of polar terrain to understand the variations of the trench geology with location.
Patterned ground looks from the air like a irregular gridwork etched onto the surface. Many of the shapes formed by the grid are polygonal with a characteristic size of 5 meters across. These same designs are seen by spacecraft orbiting Mars and are caused by the expansion and contraction of subsurface ice. In the coldest weather the ice contracts forming cracks at the polygon boundaries. Loose soil and rock can slide into these cracks preventing them from closing when the weather warms. Our goal is to sample both the centers of polygons and the boundaries looking for differences and similarities.
When Aaron and I arrived on Sunday the 23rd a trench across a polygon boundary was already dug about half a mile East of camp. The depth to the ice was 28 cm, about the depth of your head, and it was quickly melting due to the exposure to warmer temperatures and wetting the bottom of the trench. Samples had already been acquired, but Sam wanted a cross section of the icy soil at the bottom of the trench. He knelt down in the icy trench and using a metal curry brush with 1 mm notches he scraped his way down 5 cm taking 50 samples on the way. This useful tool was provided by one of his daughters who used it to groom the family dog.
Sam is a professor of chemistry at Tufts University and has spent his spare time over the last 4 years testing the MECA wet chemistry cells in his laboratory. MECA is one of the science analysis instruments on the deck of our spacecraft and is designed to provide the analytical chemistry of the Martian soil after mixing it with water. He has brought a flight-spare instrument with him to Antarctica and is determined to analyze a subset of samples here. He will soon discover that there is a hidden weakness in his instrument that prevents a full description of the local soil chemistry.
Aaron has also brought a flight-like instrument with him: the thermal and electrical conductivity probe (TECP). As a Mars geologist at NASA Ames in Sunnyvale, CA, Aaron has spent years wrestling with instrumentation preparing for the day when one of his instruments will return data to Earth. He quickly sets up a lab space where he will spend many hours over the next few days first debugging the hardware, then the software. Tonight is the test run that will set his field work in motion.
The tantalizing danger of a hard deadline has motivated Aaron and just two hours before the helo arrives to take us back to Mac Town he has dug a trench and with his coat over his head to see his computer screen and his machines powered by an extension cord the first data is taken. If one did not know he was there it would look like someone had set a red tent for the elves that inhabit the valley when no one is here to see them.
I must end this blog now to prepare for the helo's arrival in an hour. We are tidying up the campsite so that it appears that we have never been here. Then, off to the "big" city for the New Year's weekend.