2011 Annual Science Report
University of Wisconsin Reporting | SEP 2010 – AUG 2011
Project 6A: Astrobiology and Habitability Studies Supporting Mars Research and Missions
Field research at Mars analogs sites such as desert environments can provide important constraints for instrument calibration and landing site strategies of robotic exploration missions to Mars that will investigate habitability and life beyond Earth during this decade. We report on astrobiology field research from the Mars Desert Research Station (MDRS) in Utah Hanksville conducted during the EuroGeoMars 2009 campaign. EuroGeoMars 2009 was an example of a Moon-Mars field research campaign dedicated to the demonstration of astrobiology instruments and a specific methodology of comprehensive measurements from selected sampling sites. Special emphasis was given to sample collection and pre-screening using in-situ portable instruments. We have investigated 10 selected samples from different geological formations including Mancos Shale, Morrison, and Dakota Formation as well as a variety of locations (surface, subsurface and cliffs) partly in-situ in the habitat or in a post-analysis cycle. We compiled the individual studies and tried to establish correlations among environmental parameters, minerals, organic markers and biota. The results are interpreted in the context of future missions that target the identification of organic molecules and biomarkers on Mars.
We have characterized the mineralogy, organic compounds and microbiology of 10 selected sample sites from the Utah desert. The samples were collected under sterile conditions at desert areas of Utah in the vicinity of MDRS in Hanksville (Foing et al. 2011), see Figure 1. The samples were partly analyzed in situ and later distributed to the various laboratories for post-analysis. Soil sample properties such as pH value and elemental composition of K, P, Mg, and nitrate were measured in the MDRS habitat laboratory (Ehrenfreund et al. 2011).
On-site Polymerase Chain Reaction (PCR) using specific primers in combination with agarose gels identified biota of several domains shortly after collection (Thiel et al. 2011). Post-analysis studies determined the total carbon content (Orzechowska et al. 2011). The concentrations of polycyclic aromatic hydrocarbons (PAHs) have been determined by using the solid phase micro extraction (SPME) method that provides good recoveries for small PAHs that are usually targeted by planetary missions (Orzechowska et al. 2011).
Amino acids were extracted from soil samples and analyzed on a Gas Chromatograph Mass Spectrometer (GC-MS) (Martins et al. 2011). Culture-independent molecular analysis directed at ribosomal RNA, was used to investigate the detailed microbiology of desert samples. Phylogenetic analysis revealed an extraordinary variety of putative extremophiles, mainly Bacteria but also Archaea and Eukarya. These comprised radioresistant, endolithic, chasmolithic, xerophilic, hypolithic, thermophilic, thermoaci-dophilic, psychrophilic, halophilic, haloalkaliphilic and alkaliphilic microorganisms. In summary, the data revealed large difference in occurrence and diversity over short distances (Direito et al. 2011). Mineralogy investigations were performed using Infrared spectroscopy and X-ray diffraction analysis (Kotler et al. 2011).
Compared to extremely arid deserts (such as Atacama), organic and biological material can be identified in a number of samples and subsequently be used to perform correlations studies. Among the important findings of this astrobiology field research campaign are the diversity in the mineralogy composition of soil samples even when collected in proximity, the low abundances of polycyclic aromatic hydrocarbons and amino acids and the presence of biota of all three domains with significant heterogeneity (Kotler et al. 2011, Orzechowska et al. 2011, Martins et al. 2011, Direito et al. 2011). Clay-rich samples from the Morrison formation seem devoid of amino acids and biota. In-situ analysis investigations of habitability were optimized to quantify organic molecules that are targeted by planetary organic detection instruments, such as amino acids and PAHs. Whereas PAH concentrations and in particular naphthalene (likely of atmospheric origin) could be measured in all samples, the abundances did not exceed ng/g levels (Orzechowska et al. 2011). Amino acid levels showed a larger heterogeneity; only 4 samples showed abundances in the ppm level (Martins et al. 2011) similar to results obtained from the Atacama desert.
Results from the EuroGeoMars 2009 campaign show that samples in which microorganisms could be observed after PCR amplification, had significantly lower clay particle content than samples in which microorganisms were not detected (Ehrenfreund et al. 2011). No significant correlation was observed between amino acids and DNA yield or positive PCR signals. Microbial numbers and diversity do not appear to be correlated with neither organic content nor mineralogy. Instead, the dominant factor in bacterial number may be soil porosity and lower clay particle content. The successful hunt for organics will be a trade off between several parameters, including the original organic molecule concentrations, the preservation potential, extractability and the instrument performance (Ehrenfreund et al. 2011).
For Mars exploration, top-level trades incurred during site selection may limit the ability to access the most desirable regions with a high probability for the preservation of organic compounds, see Figure 2. Once a science platform is landed on Mars, the search for organics can be further impeded by sample processing and delivery constraints. The EuroGeoMars 2009 campaign was not limited by sample access as may be the case on Mars (e.g. need for drilling) and appropriate precautions were taken to prevent sample contamination (e.g. aseptic collection and storage). Additionally, the environmental parameters that result in the degradation of organic compounds are less extreme at the Utah site than they are in Atacama Desert and on Mars. Yet, even with unrestricted access to areas with high organic preservation potential (e.g. clay-rich materials) the recovery of organics is challenging. The level of organic material present in clay will strongly depend on its deposition history, diagenesis and specific composition. Field research conducted during the EuroGeoMars 2009 campaign shows the need to further optimize extraction procedures to analyse biomarkers and organic molecules in future sampling campaigns.
The data are published in a special issue of the International Journal of Astrobiology:
S. Direito, P. Ehrenfreund, A. Marees, M. Staats, B. Foing, W. Röling (2011) “A wide variety of putative extremophiles and large beta-diversity at the Mars Desert Research Station(Utah)”, Intern. Journal of Astrobiology 10/3, 191-208
P. Ehrenfreund et al. (2011) “Astrobiology and habitability studies in preparation for future Mars missions: trends from investigating minerals, organics and biota”, Intern. Journal of Astrobiology 10/3, 239-254
B. H. Foing et al. & ILEWG EuroGeoMars 2009 team (2011) “Field Astrobiology Research in Moon-Mars analogue environment: Instruments and Methods”, Intern. Journal of Astrobiology 10/3, 141-160
Z. Martins, M. A. Sephton, B. H. Foing, P. Ehrenfreund (2011) “Extraction of amino acids from soils close to the Mars Desert Research Station (MDRS), Utah”, Intern. Journal of Astrobiology 10/3, 231-238
G.E. Orzechowska, R.D. Kidd, B.H. Foing, I. Kanik, C. Stoker, P. Ehrenfreund (2011) “Analysis of Mars Analog Soil Samples Using Solid Phase Microextraction, Organic Solvent Extraction and Gas Chromatography/Mass Spectrometry”, Intern. Journal of Astrobiology 10/3, 209-220
C. Thiel, P. Ehrenfreund, B. Foing, V. Pletser, O. Ullrich (2011) “PCR-based analysis of microbial communities during the EuroGeoMars campaign at Mars Desert Research Station, Utah”, Intern. Journal of Astrobiology 10/3, 177-190
J.M. Kotler, R.C. Quinn, Z. Martins, B.H. Foing, P. Ehrenfreund (2011) “Analysis of Mineral Matrices of planetary soils analogs from the Utah Desert”, Intern. Journal of Astrobiology 10/3, 221-230.