nai

Project Progress

2007 featured the fourth Summer Undergraduate Internship in Astrobiology, a ten-week residential research program at the Goddard Center for Astrobiology (GCA). (http://astrobiology.gsfc.nasa.gov/education.html) Competition was very keen, with an oversubscription ratio of 3.0. Students applied from over 32 colleges and universities in the United States, and 10 Interns from 9 institutions were selected. Each Intern carried out a defined research project working directly with a GCA scientist at Goddard Space Flight Center or the University of Maryland. As a group, the Interns met with a different GCA scientist each week, learning about his/her respective area of research, visiting diverse laboratories and gaining a broader view of astrobiology as a whole. During a Field Trip to the U. S. Naval Observatory (USNO) in Washington, D. C., Interns saw two historical telescopes: the Six-inch Transit Circle Telescope used to mark the precise positions of stars (to assist marine navigation), and the 26-inch Refracting Telescope with which Asaph Hall discovered the two moons of Mars (Phobos and Deimos). They also visited the USNO Master Clock, the nation’s official timekeeper. At summer’s end, each Intern reported his/her research in a power point presentation projected nation-wide to member Teams in NASA’s Astrobiology Institute, as part of the NAI Forum for Astrobiology Research (FAR) Series. (http://astrobiology.gsfc.nasa.gov/main07.html)

Brief Summaries of Research are given below:

Ariel Lewis (Eckerd College) was mentored by Drs. Marla Moore (GSFC) and Reggie Hudson (Eckerd College). Ariel worked in the Cosmic Ice Laboratory and investigated the properties of carbonic acid (H2CO3). She prepared this compound by combining HBr and bicarbonate salts at cryogenic temperatures, and using infrared spectroscopy to follow H2CO3 formation on warming the mixture. She compared the spectra and stability of the H2CO3 formed in this way with that formed by ion-irradiating mixed CO2-H2O ices. She also measured, for the first time, the energy of sublimation of H2CO3 and its vapor pressure vs. temperature. Ariel demonstrated that carbonic acid is likely to form in places as diverse as icy satellites (e.g., Europa, Ariel, Triton), Mars, and comet nuclei. Her work will help guide future searches for carbonic acid that are needed for evaluating its astrobiological potential. In a separate project, Ariel worked on radiation-chemical reactions to form amino acids in carbonaceous asteroids, and investigated the reported enantiomeric excesses of isovaline and valine in the Murchison meteorite.

Lorne Loudin (Keene State College) mentored by Drs. Richard Walker, Igor Puchtel, and Daniel Glavin (GSFC), worked with the Walker group at the University of Maryland and was involved in the chemical analysis of highly siderophile elements in lunar impact melt breccias that resulted from the major basin-forming impacts. The objective of this work was to learn geochemical techniques for such measurements, then to acquire new results and compare them with the existing database for lunar, meteoritic and terrestrial samples. The abundance of highly siderophile elements (Re, Os, Ir, Ru, Pt, Pd, Rh & Au) was determined for three 200 milligram Apollo lunar sub-samples. These data show that: 1. breccia 76055 is most similar to Ordinary and Enstatite Chondrites on plots of 187 Os/ 188 Os vs. Pt/Ir; 2. 76055 overlaps the HSE data for the aphanite samples 73215 and 73255; 3. More than one chemical composition of an impactor can be inferred in the Serenitatis Basin (Puchtel et al., in review), Norman et al. 2002); 4. Some impact melts have HSE signatures that diverge from known chondritic values (Puchtel et al., in review). Organic analysis yielded minute trace levels of amino acid, consistent with previous studies of lunar soils (Glavin). No non-protein amino acids of extraterrestrial origin were identified (Glavin).

Steven Manning (University of Maryland), was mentored by Dr. Joseph Nuth (GSFC). Steve measured the rates of Fischer-Tropsch type reactions for production of organic volatiles catalyzed by carbonaceous deposits on iron silicate smokes, as contrasted with the rates on the iron silicate smokes themselves. Experiments were carried out as a function of reaction temperature and total number of experiments using a single sample of catalytic materials. Using reagent gases CO, N2, and H2, carbonaceous coating formed on the silicates after repeated exposure (~2nd to 3rd flush of reactive gases). The organic coating did not stop catalysis: the rate was even greater than that of the clean silicate grains. The catalytic nature of the organic coating allows for further production of important (possibly prebiotic) organics throughout the Solar Nebula even well after the silicate grains become coated. Analysis of the organics produced was begun.

Justin Nieusma (The College of New Jersey) was mentored by Dr. Geronimo Villanueva, NPP at GSFC. Justin analyzed high resolution infrared spectra of Mars acquired at the W. M. Keck Observatory (Mauna Kea, HI), emphasizing CO2 bands revealed in a spectrally complete survey of the 1.1 – 1.4 µm spectral region. Working with these highly advanced spectra, he studied and removed undesired instrumental effects (e.g., spectral-fringes, and electronics ground-offsets) and provided calibrated spectra across the disk of Mars. He retrieved absolute atmospheric surface pressure with high confidence, and showed that it followed topographic features (craters, lowlands, highlands). When measured with trace constituents, the simultaneous measurement of the principal atmospheric gas permits quantitative measurement of mixing ratios. His results will help when testing the existence of active vents and their possible seasonal dependence.

Heidi Owens (Auburn University) was mentored by Drs. Jennifer Eigenbrode and Paul Mahaffy (GSFC). She also worked closely with other team members developing the Science Analysis at Mars (SAM) instrument for the 2009 Mars Science Laboratory, a mission to investigate the habitability of Mars. Heidi analyzed complex organic compounds using pyrolysis gas chromatograph – mass spectroscopy (GCMS), an analytical technique to be applied by SAM. She analyzed rock samples including Mars-analog samples obtained on the Arctic Mars Analog Svalbard Expedition (AMASE). She identified a variety of aromatic hydrocarbons and alkanes in a hydrocarbon-rich dolomite rock, which she confirmed by comparison to standards. Heidi also worked on optimizing organic extraction conditions for laboratory and field-based pyrolysis.

Nadezhda Radeva (Connecticut College) was mentored by Drs. Geronimo Villanueva and Michael Mumma (GSFC). Nadya analyzed high resolution infrared spectra of Mars acquired at the W. M. Keck Observatory (Mauna Kea, HI), emphasizing bands of CO, H2O, and O2 revealed in a spectrally complete survey of the 1.1 – 1.4 µm spectral region. Working with these highly advanced spectra, she studied and removed instrumental effects (e.g., hot and dead pixels, spectral-fringes, and electronics ground-offsets) and provided calibrated spectra across the disk of Mars. She extracted the column abundance for water point-by-point along the central meridian of Mars, showing that it correlated with major landforms such as the Hellas basin.

Cara Rahon (Iona College) was mentored by Dr. Michael DiSanti (GSFC). Cara analyzed spectra of comet C/2004 Q2 Machholz, an Oort cloud comet observed with the NIRSPEC spectrometer at the W. M. Keck Observatory (Mauna Kea, HI). Using our latest processing software, she extracted calibrated spectra from raw frames, analyzed the detected cometary spectral lines in terms of rotational temperatures and production rates, and quantified the production rates for seven molecular species (H2O, CO, CH3OH, CH4, C2H6, C2H2, and HCN). She compared her results with those taken seven weeks later and showed that the chemical composition was unchanged, thereby suggesting that the comet was homogeneous in its composition.

Joshua Stern (Brown University) was mentored by Drs. Jason Dworkin and Daniel Glavin, (GSFC). Josh investigated hydroxy and carboxylic acids by derivatizing them with the chiral fluorescent tag agent R-DBD-APy. He then used High Performance Liquid Chromatography and Time-of Flight Mass Spectrometry to quantify the chiral yield. He showed that the approach did not provide the needed sensitivity for carboxylic acids, and identified several alternate avenues for investigation.

Kamen Todorov (Connecticut College) was mentored by Dr. Drake Deming (GSFC). Kamen analyzed infrared spectra of HD209458 acquired with the Spitzer Space Telescope during secondary eclipse of the exoplanet (HD209458b). He used time series acquired at 16 µm wavelength with Spitzer’s IRS “blue” peak-up array camera to quantify the depth of the eclipse, i.e., the fraction of the total pre-eclipse infrared light contributed by the exoplanet. He then derived the effective temperature of the emitting layer (~1100K), showing that it was too hot for liquid water to form.

James Doty (Rice University) was mentored by Drs. Jason Dworkin and Daniel Glavin (GSFC). Jim initiated a search for aromatic molecules in carbonaceous meteorites. He extracted organics from a sample of a CM chondrite (Murchison) and a CM-2 chondrite (LEW90500), and subjected them to analysis using High Performance Liquid Chromatography and Time-of Flight Mass Spectrometry in the Astrobiology Analytical Laboratory. Nucleobases were detected (xanthine, guanine, and/or uracil) along with numerous unidentified spectral features. Work is continuing.