Featured Image: Iceberg in North Star Bay, Greenland by Jeremy Harbeck – NASA, Public Domain
Authors: Michael J. Malaska, Rohit Bhartia, Kenneth S. Manatt, John C. Priscu, William J. Abbey, Boleslaw Mellerowicz, Joseph Palmowski, Gale L. Paulsen, Kris Zacny, Evan J. Eshelman, and Juliana D’Andrilli
Like the rings of a tree, core samples extracted from glacial ice preserve a unique record of past events. But instead of recording seasonal growth, the ancient ice sheets of Antarctica and Greenland have preserved the conditions of long gone climates and ecosystems. Some sheets have continuously accumulated so much snowfall over the past series of millennia that in some places the ice can reach depths that are miles deep. Analyzing this immense glacial record can inform us about not just the global patterns of climate change, but also the evolution of microbial life on Earth, and maybe even the icy worlds of our Solar System.
However, drilling down into the ice sheet and removing a column of ice can result in sample contamination, melting, and loss of information. In a new study, scientists have foregone this risky means of extraction and employed an all-new instrument to detect and analyze microbes and organic molecules trapped in the ice. Their findings suggest that a more secure analysis of subterranean ice is possible, offering a significant alternative to traditional ice coring methods. What’s more, this instrument could also make it easier to study ice on distant planets and moons thought to contain traces of life.
The new instrument known as WATSON (the Wireline Analysis Tool for the Subsurface Observation of Northern ice sheets) has now surveyed a new section of ice by drilling further down into an existing borehole at Summit Station in Greenland. The borehole served as an analogue, or test site, for scientists to investigate the presence of frozen microbes, how they got trapped at different depths within the ice sheet, and if we might find a similar scenario somewhere out beyond Earth. Since ice can house and sustain microbial communities between its porous grains and within brine channels, the frozen poles of Mars, the oceanic world of Europa, the ice-covered Enceladus, and Titan’s surface features of water-ice are now leading contenders as potential habitats for extraterrestrial life.
WATSON is equipped with a robotic drill arm as well as an imaging spectrometer capable of detecting the chemical structure of molecules by measuring ultraviolet wavelengths of light that are invisible to the human eye. The authors of the study report WATSON found traces of specific microbial species and organic compounds, while the new drill design ensured a clearer and wider view of the ice without the threat of melting or damage in transport. The original borehole was already about 85 meters (279 feet) deep, and the WATSON experiment drilled an additional 26 meters (85 feet), extending the hole to approximately 110 meters (360 feet) down. By observing an ice sample directly in place, the authors conclude WATSON demonstrates a new and improved method for studying ice-bound organic matter and its distribution deep within ice sheets.
Perhaps most compelling is the prospect that in-situ, or “in place,” instruments like WATSON could address the challenges of robotic exploration to our planetary neighbors’ icy depths. Even if we eventually overcome the substantial distance and technical ingenuity required to return ice samples to Earth, ultimately that sampling would still rely on bulk ice core extraction. Instead, WATSON and in-situ analysis may resolve the issues surrounding extraction and transport, and could support thorough astrobiological investigations in future planned missions to these uncharted, and conceivably living worlds.
New instrument maps and preserves frozen habitats on Earth- and potentially icy worlds by Emily Felder is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.