DSC_1838  Professor Sarah Stewart Johnson (PI)

I’m an assistant professor at Georgetown University and a visiting scientist at NASA’s Goddard Space Flight Center. I’m fortunate to get to work with some amazing people!  At present, my lab includes:

   Elena Zaikova
I am a postdoctoral fellow investigating the evolution, adaptation and evidence of activity of microbial communities inhabiting extreme environments like Antarctica. My primary research interests lie in understanding how microbial communities assemble and function, and how they help shape the ecosystem.
 unnamed   Maëva Millan
I am a postdoctoral fellow working on the chemical and mineralogical composition of the Martian surface using the Sample Analysis at Mars (SAM) experiment onboard the Curiosity rover of the MSL mission. In particular, I am searching for organic molecules and biomarkers on Mars and investigating methods of their preservation in various kind of Martian minerals. In addition to data collected from SAM, I work with Martian analog samples from terrestrial environments. I recently received my Ph.D in specialty Astronomy and Astrophysics in France on a similar project. My daily laboratory experiments are physio-chemical analysis using pyrolysis and wet chemistry coupled to gas-chromatography mass-spectrometry. I try to replicate SAM conditions as closely as possible to help data interpretation and the search of organic matter. Besides work, I love hiking and taking pictures of the beautiful places, landscapes and people I meet during my trips. 
 unnamed  Nicole Wagner
I am a Ph.D student in the Johnson Biosignatures Lab. After receiving a B.S. from Stanford in physics with a focus on astronomy and a B.S. from Portland State University in biology, I decided to merge my interests in the study of life in extreme environments used as Mars analogs here at Georgetown. My foray into the world of extremophiles began in Anna-Louise Reysenbach’s lab at Portland State University where I spent my days sifting through the genome of hyperthermophilic archaea. In my free time, I re-watch episodes of Star Trek, obsess over all things SpaceX, and dote on my toy poodle.
 Anaïs  Anaïs Roussel
The questions that I am passionate about pertain to how life developed and adapted to extreme and variable environments. I am particularly interested in biomarkers, how to find them and understand them, and how we can use this knowledge in the search for life in our solar system. Before coming to Georgetown to begin my PhD, I studied engineering in biotechnologies in France and researched biomarker preservation in ancient rocks in Oman as a member of the Summons Lab at MIT.
 DSC00351  Angela Bai
I’m a recent graduate of Georgetown College with a Bachelor’s degree in biology. As a research assistant in the Johnson Biosignatures Lab, I study the ancient microbial communities of Antarctica’s Dry Valleys in order to understand how life can survive in extreme environments. I am fascinated by the diverse paradigms with which we can conceptualize life in the universe. Besides in Regents 511, I can also be found cooking or geeking out about sustainable design.
 julie  Julie Bevilacqua
I’m a rising senior at Georgetown University studying Biology of Global Health and English. My research focuses on the microbial communities in the soils and microbial mats of the Dry Valleys in Antarctica. I’ve also worked in the field to collect samples at Craters of the Moon in order to study the impact of non-photosynthetic microbes on mineral deposition in lava tubes. I’m interested in the metabolic mechanisms for survival in harsh conditions and in the diverse applications of new sequencing technology, from research labs to the field to clinical settings. Outside the lab, I like to spend my time reading, baking, and traveling.
 Mia  Mia Vanderwilt
I am a senior at Georgetown University receiving a B.S. in Science, Technology, and International Affairs with a concentration in Environment and Energy. My prior research has been variably focused on drought mitigation policy in India, modeling shifts in Icelandic fishery distributions and glacier mass balance on the Juneau Icefield in Alaska. I am interested in the influence of biogeochemical processes in glacial environments on extremophile community composition, adaptation and function, and the potential astrobiological implications of this interaction. This October, I will be accompanying Nicole to Lake Untersee in Antarctica. When not exploring the sub-Arctic and Antarctic, I love skiing, backpacking, kayaking and trail running.
 anushree  Anushree Srivastava
I am a short-term scholar at NASA Goddard Space Flight Center and Johnson Biosignature Lab. I am working with the SAM (Sample Analysis at Mars) team, assisting in astrobiology experiment onboard the Curiosity rover of the MSL mission. My work focuses on identification of organic molecules potentially detected on Mars by SAM. I have completed MSc in Biotechnology from the University of Essex, UK, where my research focused on the detection of haloarchaeal signatures within the Messinian halite (~6 million years old) fluid inclusions, as well as testing the long-term survivability of halophiles entombed inside the lab-grown halite crystals.


Lab alums include:

mark deirdre
Maggie Weng Maya Samuels-Fair


mark deirdre Ben Indo1 (1)
Mark Sutton Deirdre Collins Ben Johnson


IMG_0354 savannah 2015-05-22 15.07.15
Monica Soni Savannah Fuqua Allee Torres