Читать книгу Astrobiology - Charles S. Cockell - Страница 83

Affiliation: NASA Jet Propulsion Laboratory (JPL), Pasadena, CA, USA

What was your first degree subject? My first set of degrees were two bachelor's degrees, one in Geology and one in Materials Science. I learned in my master's degree how to build an astrobiology mission, and finally I went on to earn my PhD in Geobiology and Geological Sciences. I was fortunate to also work as a mission scientist on the 2004 Mars Exploration Rover mission while in college. My job on the mission was to examine microtextures from abraded rocks in outcrops where groundwater had infiltrated the sedimentary sections that we were exploring. This helped pave the way for my future career as an astrobiologist. While it was proven that water had existed on Mars, my questions started to form around how life could utilize such waters for survival and how evidence of biogenic activity could be preserved in salt and evaporite mineral veins.

What do you study? I am a geobiologist and astrobiologist who studies how life is preserved and maintained in hypersaline and evaporite salt mineral environments where ancient lakebed systems have dried or in modern lakes that are currently evaporating. I also study these ancient aqueous systems on Mars using in-situ and orbital data from rovers and orbiters. Moreover, I examine brine environments that are analogous to Europa's modern ocean–ice interfaces.

What science questions do you address? How can we validate true biological (biogenic) features from abiogenic ones? How can evidence of life and its processes be maintained deep underground in the Martian subsurface? How different would that life be from Earth's biomes and would we even detect it? What are the features of preserved microbiological processes in evaporites? How sustainable are these same features over geologic time? How can we use the single data point of life on Earth (including its diversity) and use that for life as we don't know it in our Solar System? Since 2017, I've co-led the Origins and Habitability Laboratory at JPL where we are looking to answer these questions and many others related to physical biosignatures and chemical biomarkers in extreme environments.

How did you get involved in astrobiology research? When I started my career, the focus was showing how widespread water was on Mars during the late Noachian/early Hesperian. Eventually that evolved to understanding how the mineralogy, formed from those same waters, could capture potential evidence of life and act as a record of biogenic processes. I'm also a geobiologist for extreme environments on Earth. Essentially, on our own planet astrobiology is geobiology. I wanted to contribute answers to astrobiology questions that dealt with validating records of ancient and modern preservation of life, how this evidence was recorded in halite and gypsum and other evaporite mineralogy, and using life “as we know it” to help understand “life as we don't know it” in our Universe. I got involved with astrobiology research essentially from seeing mineral formations on Mars precipitated and modified by ancient waters. This led me to closed-basin lake systems on Earth that recorded microbial communities that were once living in the nearby waters. The fieldwork led me to lab work where I created analog evaporite samples of what I observed in the field and on Mars through in-situ and orbital images and spectra. Incorporating all three aspects: field geobiology, laboratory work, and the context of ancient Mars and modern Europa has allowed for a clear and challenging pathway for understanding how cellular life can be preserved and maintained.