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Yellowstone Nation Park sampling expedition for Astrobiology
- July 2013 -
Yellowstone National Park is an outstanding place to do Astrobiology research. Created by 3 major eruptions 2 million, 1.3 million, and 600 thousand years ago (we’re overdue for the next one!), and punctuated by smaller eruptions since, Yellowstone is a natural laboratory to investigate life in extreme environments. The shallow magma chamber located 1 or 2 miles below the park – itself located within the caldera (collapsed terrain) of the eruptive events - and fueled by a likely mantle plume, gives life to hundreds of hot springs, geysers, and boiling mud pots. These environments, instantly lethal to humans, are home to a large array of microbes, living off the material transported by water as it interacted with rocks at depth, and brought to the surface often in spectacular ways.
Drs. Eric Boyd, Kirsten Fristad and myself, are in Yellowstone to survey the dissolved gas hydrogen in these springs. The reaction of water with rock produces hydrogen (H2) via several processes that are widespread on Earth. Hydrogen may also have a biological origin from such processes as fermentation. The geological processes that can form hydrogen are expected to occur on other planets where liquid water and rocks are present. The geological production of hydrogen represents a continuous supply of chemical energy for life. Hydrogen utilizing microbes are of particular interest because they are both widespread and are deeply rooted in the phylogenic tree of life, implying they may have emerged extremely early in the evolution of life on Earth, and possibly even at the origin of life. As a result, hydrogen-based microbes are strong candidates for the potential of life beyond Earth. Our goal this week is to measure the variation in hydrogen abundance in hydrothermal springs across Yellowstone and its distinct rock types, in order to assess whether these springs can host primitive microbes; and if so ask the following questions “why” and “how”? The first step in this research is understand what concentrations of H2 can be expected in such systems.
Kirsten and I left from NASA Ames Research Center on a 2 day road trip across California, Nevada, Idaho to finally arrive in West Yellowstone, MT. The scenic drive was fantastic, particularly when we reached terrain that had a deep volcanic origins, such as the Snake River Plain (image below). Being both rock enthusiasts, it was really cool to see how the Snake River has incised the flood basalt. With our “roadside geology” books, we turned a road trip into a geology lesson in its own right.
On our first day in the field, and equipped with the necessary sampling permits from the Park Service, we packed up our supplies in West Yellowstone, and met Eric at the Norris Geyser Basin inside the park, where we decided to work in the Crater Hills Geyser area. Crater Hills is on the east side of the park, and so we made it the first stop in our park survey. The pullout for the hike to Crater Hills is located by a scenic view of Lamar valley. Hundreds of bisons could be seen in the distance, with a few not too far from us during our hike up to the sampling site. In fact, once we arrived at Crater Hills, we had to wait to sample one of the hot spring because of a bison taking a nap by the spring! These are beautiful, yet dangerous animals, so we made sure to keep a safe distance.
Crater Hills is dominantly occupied by acidic hot springs. The soil around them is bare, as the acidic flows have leached out all plant nutrients. The fact that such springs occupy a depression just shows how effective those acidic springs are at eating through the rocks. Their existence created the depression! We sampled for hydrogen at four different pools by extracting the gas from collected spring water. Each spring had a different color and bubbling intensity. The main Crater Hills Geyser was by far the most impressive with its vigorous activity (see video below)!