Many areas of Earth have temperate, stable, and nutrient-rich environments that allow life to flourish. Not all parts of Earth are like this. Some areas, such as the Greenlands Ice Sheet, are not suitable for human habitation.
It is only natural that we will be exploring worlds that may not be suitable for our search for life in the Solar System. Our most likely targets are icy worlds such as Saturns moon Enceladus and Jupiters moon Europa. These frozen worlds are home to warm oceans beneath layers of ice.
What can the Greenlands cryo-ecosystems reveal about searching for life in icy bodies such as Europa and Enceladus,
Greenlands Ice Sheet (GrIS), is a harsh environment for any organisms. This is an extreme environment in which life must deal with long periods of sub-zero temperatures. Due to the magnetosphere's nature, Earth's polar regions also receive more radiation than other areas. Scientists believe that the GrIS could be a useful tool in our search for life elsewhere on Earth, especially in extreme environments.
Laura Snchez Garca is a geoscientist with the Centro de Astrobiologa, Madrid, Spain. Sanchez-Garcia visited Greenland's field site in July 2021 in order to study microbiological cryo-ecosystems. Sanchez-Garcia said that the GrIS acts as a laboratory to study these systems. The ice sheet could have implications for our search for life on Europa and Enceladus.
Laura Sanchez-Garcia using the GrIS ice drill. Image Credit: Laura Sanchez-Garcia/CAB (INTA-CSIC)
GrIS is not the only thing that has attracted attention. Glacial lakes, melting streams and peat bogs are all possible options. All of these environments could be host to microbial environments representing different stages of evolution of psychrophilic microorganisms.
Sanchez-Garcia's research was focused on so-called lipid biomarkers. These organic molecules can be traced back directly to their origin organisms. Lipids are fats and waxes. They can be preserved in sedimentary rocks or in ice over geological time periods, which is not possible with other markers such as DNA and proteins. Bioinformatics and genomics have made it possible to study lipid biomarkers and helped us understand the history of Earth's microbial life. These same breakthroughs are shaping our search for life elsewhere in the Solar System.
Sanchez-Garcia and Daniel Carrizo, her colleague, collected ice core samples at different locations around the GrIS. They collected ice core samples from various locations around the GrIS. They also collected meltwater samples, sediment samples from bedrock erosion, as well as water samples from various types of lakes including a salt lake. All the samples were filtered, and then analyzed. Water samples were chemically analyzed, while sediment and frozen samples were analyzed to determine lipid biomarkers.
Sediment resulting from the erosion glacial bedrocks of the Greenland Ice Sheet. Image Credit: Laura Sanchez-Garcia/CAB (INTA-CSIC)
The team collected samples of mosses, grasses and lichens. The team was able to see the new isotopic signatures of the vegetation that contribute to the soil's lipidic fingerprint. Next steps?
Kangerlussuaq Planetary Analogue Field site: Soil and Vegetation studies Credits: Laura Snche Garca/CAB (INTA–CSIC).
Sanchez-Garcia & Carrizo are back in lab with their samples. They plan to publish their findings. They are currently focusing their research on three subjects:
The Greenlandic glacier Issunguata Sermia was found to have psychrophilic metabolisms and sources.
The Molecular and isotopic distributions of lipid biomarkers within glacial versus rainfallwater lakes in the Greenlandic region, Kangerlussuaq.
Based on molecular and isotopic biomarkers of lipids, biological succession in Greenlandic soils following glacier retreat
These studies are crucial for understanding Earth's history and for astrobiology. These data are used to build models that show how biology, chemistry, and geology interact. This data gives scientists a better understanding about the Earth's carbon cycle and how oxygen is built up in the atmosphere. This information is crucial for complex organisms to develop.
The search for life on other planets is made easier by insights into Earth's development. These insights into the development of extremophiles on Earth help to create mission profiles for places such as Europa and Enceladus. Successful missions depend on asking the right questions and using the right technology. This research helps to refine the questions.
Artist's impression of Europa's interior, based upon data from Galileo space probes Credit to NASA
Astrobiologists believe that water must come into contact with rocks in order for life to exist. Scientists believe that rock and briny water are in close contact on both Enceladus as Europa. Ice is another important feature. Sanchez-Garcia and other researchers have the opportunity to improve their understanding of how it all works by studying the Greenland Ice Sheet.
Astrobiology's overarching goal is to understand how Earth became habitable. What, when and why did Earth become habitable? How can we find out if other planets in the Solar System are habitable?
It is unlikely that one big answer will be given to all of these questions. It is more probable to find a series smaller answers. Perhaps this research at Greenland Ice Sheet can provide some.
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