The NfoLD Webinar Series
The next webinar will be:
Dr. Heather Graham
NASA Goddard Spaceflight Center
Thursday, 23 April, 10 am Pacific (17:00 UTC)
for Extant Life Detection
About Dr. Heather Graham
Dr. Graham is an organic geochemist with widely varied research experience ranging from paleoecology to phytochemistry to astrobiology. She is profoundly curious about the natural world, the history of life, the vast connections between biotic and abiotic systems, and what evolution can tell use about our future.
When not in the lab, she is equally passionate about building casual and formal educational ecosystems that foster creativity, build diversity, and inspire scientific excellence. And she's also an active science communicator with collaborations in art, theater, and digital media.
Abstract for the Webinar
Current strategies for biosignature detection rely mainly on identification of well-established and widely accepted features and signatures associated with the biologic processes of life on Earth, such as particular classes of molecules and isotopic signatures, enantiomeric excesses, and patterns within the molecular weights of fatty acids or other lipids. As we begin to explore icy moons of Jupiter and Saturn and other destinations far beyond Earth, methods that identify unknowable, unfamiliar features and chemistries that may represent processes of life as-yet unrecognized become increasingly important. Life detection without presumption of terran characteristics presents a formidable challenge to any astrobiology strategy. How do we contend with the truly alien? “Agnostic” approaches to biosignature and life detection are designed to target generic characteristics of life that distinguish it from abiotic chemistry. These methods require us to utilize existing instrumentation in more general ways, pursue new leads, and synthesize data with probabilistic approaches, since agnostic methods may trade definitiveness for inclusivity. This talk will outline some of the approaches under investigation in the Laboratory for Agnostic Biosignatures, discuss potential paths towards “agnostification”, and address some of the methodological problems and knowledge gaps posed by the problem of considering “life as we don’t know it”.
The Search for Chiral Asymmetry
as a Potential Biosignature in our Solar System
Dr. Danny Glavin, NASA Goddard Spaceflight Center
Tuesday, 25 February 2020
About Dr. Danny Glavin
Daniel Glavin earned a B.S. in physics from the University of California at San Diego in 1996 and a Ph.D. in earth sciences from the Scripps Institution of Oceanography in 2001 where he studied the amino acid and nucleobase composition of meteorites and exogenous delivery as a mechanism for delivering prebiotic organic compounds to the early Earth. He joined the 2002–03 Antarctic Search for Meteorites (ANSMET) team that recovered over 900 meteorites in Antarctica. In 2003, Dr. Glavin joined the NASA Goddard Space Flight Center in Greenbelt, Maryland, where he later cofounded the Astrobiology Analytical Laboratory at NASA Goddard. He was selected to be a Participating Scientist on the Mars Science Laboratory (MSL) mission in 2011 and was part of the team that discovered the first evidence of indigenous organic compounds on Mars using the Sample Analysis at Mars (SAM) instrument. He became NASA Goddard’s Associate Director for Strategic Science in the Solar System Exploration Division in 2014. Dr. Glavin is a Co-Investigator on the OSIRIS-REx asteroid sample return mission. In recognition of Dr. Glavin’s meteorite research, the International Astronomical Union named an asteroid after him, asteroid (24480) Glavin. He has received numerous awards including the 2007 NASA Goddard Internal Research and Development Innovator of the Year Award, the 2010 Nier Prize from the Meteoritical Society, and the 2014 NASA Robert H. Goddard Exceptional Achievement Award for Science.
Abstract for the Webinar
The search for evidence of extraterrestrial life in our Solar System is currently guided by our understanding of terrestrial biology and its associated biosignatures. The observed homochirality in all life on Earth, that is, the predominance of “left-handed” or L-amino acids and “right-handed” or D-sugars, is a unique property of life that is crucial for molecular recognition, enzymatic function, information storage and structure and is thought to be a prerequisite for the origin or early evolution of life. Therefore, the detection of L- or D-enantiomeric excesses of chiral amino acids and sugars could be a powerful indicator for extant or extinct life on another world. However, studies of primitive meteorites have revealed they contain extraterrestrial amino acids and sugar acids with large enantiomeric excesses of the same chirality as terrestrial biology resulting from non-biological processes, complicating the use of chiral asymmetry by itself as a definitive biosignature. Here we review our current knowledge of the distributions and enantiomeric and isotopic compositions of amino acids and polyols found in meteorites compared to terrestrial biology and propose a set of criteria for future life detection missions that should be used to help establish the origin of chiral asymmetry. Significant advances in spaceflight-qualified sample extraction, purification, and chromatographic separation technologies coupled with high-resolution mass spectrometry are needed to make these measurements. Given the complexity and limited duration of spaceflight operations and the analytical challenges associated with in situ analyses of complex organics in extraterrestrial samples, returning samples to Earth may ultimately provide the best chance to firmly establish the origin of chiral asymmetry and other potential biosignatures in our Solar System.
See this Chemical Reviews Manuscript