Exobiology Branch (Code SSX)

Mission Statement

The branch conducts interdisciplinary basic research in exobiology to understand pre-biotic chemistry, and the origin, evolution, distribution, and future of life in the Universe. We provide an interface between the external academic community and NASA programs. Our work also informs the selection, design and development of NASA life detection missions; the design and fabrication of spaceflight instruments to evaluate habitability and detect biosignatures; and the interpretation of astrobiology mission and astronomical data.

Exobiology Branch 2015

Exobiology Branch 2015

1st row left to right. David Blake, Orlando Santos, Esther Weber, Mark Ditzler, David Des Marais, Linda Jahnke 2nd row left to right. Arthur Weber, George Cooper 3rd row left to right. Michael Kubo, Rocco Mancinelli, Jackson Lee, Tori Hoehler 4th row left to right. Sanjoy Som, Thomas Murphy, Andro Rios, Mike Wilson 5th row left to right. Fathi Karouia, Craig Everroad, Milena Popović, Samantha Yim, Niki Parenteau 6th row left to right. Joshua Reynolds, Bennett Kapili, Melissa Thang, Yasaman Mortensen 7th row left to right. Adrian Carabello, Leslie Bebout, Marisa Mayer, Angela Detweiler, Mastewal Abate, Oana Marcu Sandy Dueck, Joseph Solvason

Principal Investigators not pictured. Brad Bebout, Tom Bristow, Andrew Pohorille, David Summers


The CheMin Instrument on the Mars Science Laboratory


The Exobiology Branch is home to David Blake, the Principal Investigator for the CheMin instrument on the Mars Science Laboratory, scheduled for launch in 2011.


CheMin field testing in Death Valley
CheMin field testing in Death Valley.



A Miniature Gas Chromatograph-Ion Mobility Spectrometer

The CheMin instrument utilizes X-ray diffraction and flourescence to provide difinitive minerology of rock samples (both elemental analysis and crystal structure determination).


CheMin integration on MSL

The CheMin instrument being integrated onto the MSL rover. Next stop, Mars!


Early Habitable Environments and the Evolution of Complexity

The Exobiology Branch is home to David Des Marais, the Principal Investigator of the NASA Astrobiology Institute (NAI) Ames Team, which focuses on Early Habitable Environments and the Evolution of Complexity.  The overarching goal of this scientific program is to understand the creation and distribution of early habitable environments in emerging planetary systems.  The Ames Team provides a program of integrative, mission-enabled and mission-enabling research on habitability and a thematically related program of education and public outreach focused around informal education in high-impact venues.  Andrew Pohorille, Tori Hoehler, and Sandy Dueck are also members of the Exobiology Branch and hold key roles as Lead Co-Investigators on the team.  To learn more about the NAI Ames Team, visit their website at www.amesteam.arc.nasa.gov.


NAI Team


Origin of Life Research

For nearly 40 years, the Exobiology Branch at Ames has been the main center for origins of life research at NASA, and a world leader in this scientific area. Currently, the branch has the unique feature of being the only center within the NASA Astrobiology Program that has a sustained, long-term program of theoretical and computational studies on the origins of life. This research program, which contains both molecular and system-level components, is leveraged by the supercomputing facilities at Ames and by Ames' status as the NASA lead center in information science and technology.


Pohorille Article

The image shown above is the cover art for the latest issue of the Journal of Physical Chemistry, highlighting an article by Andrew Pohorille, a Principal Investigator in the Branch, with co-authors Christopher Jarzynski and Christophe Chipot, titled "Good practices in free-energy calculations". From the abstract: "As access to computational resources continues to increase, free-energy calculations have emerged as a powerful tool that can play a predictive role in a wide range of research areas. ... In this contribution, the current best practices for carrying out free-energy calculations using free energy perturbation and nonequilibrium work methods are discussed demonstrating that, at little to no additional cost, free-energy estimates could be markedly improved and bounded by meaningful error estimates."

Dr. Pohorille is also the recepient of this year's H. Julian Allen Award, bestowed by NASA Ames for best research paper. Titled "Calculating free energies using average force", the paper appeared in the Journal of Chemical Physics (co-author Eric Darve), Volume 115, Number 20, November 2001. According to the Citation Index in the Web of Science the paper has been cited 111 times as of March 2010. From the abstract: "A new, general formula that connects the derivatives of the free energy along the selected, generalized coordinates of the system with the instantaneous force acting on these coordinates is derived. The instantaneous force is defined as the force acting on the coordinate of interest so that when it is subtracted from the equations of motion the acceleration along this coordinate is zero. The formula applies to simulations in which the selected coordinates are either unconstrained or constrained to fixed values."

The Branch is also home to Dr. Arthur Weber, a SETI Institute researcher, who works together with his wife Esther to study the pre-biotic chemistry of sugars, and how these molecules may have led to the origin of life.

Weber Lab
The role of sugars in pre-biotic chemistry.



The Branch is housed in Building 239 at NASA Ames Research Center.  Laboratory facilities available include analytical equipment for the characterization of gas and aqueous chemistry, instruments for the detection of various biomarkers including sugars and organics, microbiology facilities including the culture of microbial mat communities, electron and RAMAN microscopes, a molecular biology suite, and informatics computational capabilities.




Weekly Highlight

Planet hunters seek new ways to detect alien life Astrobiologists debate which chemical signatures would hint at life on other worlds.

In the search for life beyond Earth, false alarms abound. Researchers have generally considered, and rejected, claims ranging from a 1970s report of life on Mars to the 1990s ‘discovery’ of fossilized space microbes in a meteorite.

Rocks - JPL

Rocks Rich in Silica Present Puzzles for Mars Rover Team

In detective stories, as the plot thickens, an unexpected clue often delivers more questions than answers. In this case, the scene is a mountain on Mars. The clue: the chemical compound silica. Lots of silica. The sleuths: a savvy band of Earthbound researchers whose agent on Mars is NASA's laser-flashing, one-armed mobile laboratory, Curiosity.

Mars Rover Breaks Driving Record

Mars Rover Breaks Driving Record. The Pasadena (CA) Star-News (7/28, 89K) reports that on Monday, NASA announced that “the Opportunity Mars rover broke a world record this month when, after 10.5 years, its odometer read 25 miles.” The piece notes that “the space rover has gone 40 times above and beyond NASA’s expectations, said John Callas, Mars exploration rover project manager at the Jet Propulsion Labora

Ames Instrument Helps Identify the First Habitable Environment on Mars, Wins Invention Award

June 24, 2014


Ames Instrument Helps Identify the First Habitable Environment on Mars, Wins Invention Award 


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