| Dr. Jennifer Blank Curriculum Vitae: 
Jennifer is a geochemist who likes to study life that walks on the wild side. Testing the extremes of biochemistry is more than just setting records, however. Since most of the worlds beyond Earth sport conditions that are far less friendly than those of our own, it may be that the vast majority of all life is, in fact, of the extreme variety. By heating and squeezing molecules in fluids, Jennifer has learned that some fluid-based organic molecules that would simply disintegrate when heated in a laboratory beaker maintain their structure when the fluid is under pressure. This could clearly be an encouraging finding for those who hope to find, for example, life near a hot vent at the bottom of a deep, alien ocean. She’s also learned that if you apply sudden pressure (and concomitant heat) to organic molecules, some will survive, and others will often reassemble, or polymerize, into yet more interesting biologically relevant compounds. Imagine amino acids formed in the icy interior of a comet that later smashes into a planet. Some of the amino acids will survive the impact, and others will polymerize into peptides, which is also a biologically important compound. It seems that life’s precursors don’t mind getting smashed.
Projects
An Experimental Study of the Generation and Enantiomeric Enrichment of Sugars and Amino Acids in Cometary Impacts
NNX08AQ26G
The discovery of relatively high abundances of organic compounds such as amino acids and sugar derivatives in meteorites, comets, and the interstellar medium implies that there are relatively efficient mechanisms for producing fairly complicated organic compounds in space, supporting the notion that the building blocks of life may have been delivered to Earth by impacting asteroids and comets. Comets are the delivery vehicles of preference because they generate lower pressures and temperatures in an impact and also contain high proportions of organic material and water, the key ingredients for life. The shock chemistry associated with the behavior of organic compounds during impact remains largely unknown, due to the paucity of experimental data for relevant dynamic extreme-condition regimes.
In an earlier NASA-funded project, we conducted "comet impact" experiments in which aqueous fluids containing dissolved amino acids were subjected to hypervelocity impacts and then examined for chemical change. We made several remarkable observations; not only did fractions of the initial amino acids survive shock conditions relevant for an oblique impact, they polymerized to form peptides (rather than other less-biologically-interesting compounds) and there was no tarry, macromolecular material observed as a bi-product.
Here, we outline a 3-year program to expand previous shock chemistry work to include experiments using sugars and sugar derivatives. We propose a series of 6 impact experiments per year to test the following hypotheses: (1 ) that high velocity impacts promote a formose-type reaction to generate sugars (formaldeyde + water --> glycoaldehyde); (2 ) that sugar dimers, trimers, and higher order homologs are produced from an initial mixture of sugar monomers, as was observed with amino acids; and (3) that an initial enantiomeric excess present among amino acids and sugars will be enhanced through shock processing and dimer/polymer formation.
We propose to conduct the impact experiments using an 80-mm-bore gas gun at Los Alamos National Laboratory and a quantitative soft recovery method, already developed. Starting materials( formaldehyde, sugar compounds, amino acids and dipeptides) and recovered products will be analyzed using a combination of liquid and gas chromatography/mass spectrometry. The proposed analytical work capitalizes on procedural methods already developed to distinguish simple sugars, sugar derivatives, amino acids, and small peptides.
The proposed research directly meets a fundamental goal of NASA's Exobiology and Evolutionary Biology program to identify and understand the characteristics of our solar system that may have led to the origin of life. Our results will allow us to assess the role of impact chemistry as a mechanism for generating larger molecules and/or introducing a chiral bias to Earth’s initial inventory of prebiotic compounds.
Enantiomeric and Isotopic Analysis of Sugar Derivatives in Carbonaceous Meteorites
NNX09AC91A
The work described here will focus on the gas and liquid chromatographic analysis and mass spectrometric analysis of sugar derivatives and related compounds identified recently by Dr. Cooper. The results of this study will provide insight into the abiotic synthesis and evolution of organic molecules in space, a topic of particular interest to the Origin of Life community. An additional component of this cooperative agreement provides funds to support the participation of Dr. Blank as a science team member of ChemCam, the LIBS instrument on the Mars Science Laboratory mission scheduled for 2009 launch. Dr. Blank will work in collaboration with Dr. Chris McKay (NASA/Ames), a co-Investigator on the ChemCam project, to investigate detection limits of LIBS applied to carbonates and organic compounds.
|