Analysis of spectroscopy datasets from rover field tests in the Atacama Desert (Chile), focusing on the composition of the surface and identification of potential habitats for life

Apostolopoulos, D.

Cabrol, N. A.

Chong Diaz, G.

Cockell, C.

Coppin, P.

Dohm, J. M.

Fisher, G.

Glasgow, J.

Grin, E. A.

Hock, A. N.

Marinangeli, L.

Minkley, N.

Moersch, J. E.

Ori, G. G.

Piatek, J. L.

Rampe, M.

Smith, T.

Stubb, K.

Thomas, G.

Waggoner, A.

Wagner, M.

Warren-Rhodes, K.

Weinstein, S.

Wettergreen, D. S.

Whittaker, R.

Wyatt, M.

English

Open Research Online 

Open Research OnlineThe Open University’s repository of research publicationsand other research outputsSpectroscopic results from the Life in the Atacama(LITA) project 2004 field seasonConference or Workshop ItemHow to cite:Piatek, J. L.; Moersch, J. E.; Wyatt, M.; Rampe, M.; Cabrol, N. A.; Wettergreen, D. S.; Whittaker, R.; Grin,E. A.; Chong Diaz, G.; Cockell, C.; Coppin, P.; Dohm, J. M.; Fisher, G.; Hock, A. N.; Marinangeli, L.; Minkley, N.;Ori, G. G.; Waggoner, A.; Warren-Rhodes, K.; Weinstein, S.; Apostolopoulos, D.; Smith, T.; Wagner, M.; Stubb, K.;Thomas, G. and Glasgow, J. (2005). Spectroscopic results from the Life in the Atacama (LITA) project 2004 fieldseason. In: 36th Lunar and Planetary Science Conference, 14-18 Mar 2005, Houston, Texas, USA.For guidance on citations see FAQs.c© [not recorded]Version: [not recorded]Link(s) to article on publisher’s website:http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1563.pdfCopyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyrightowners. For more information on Open Research Online’s data policy on reuse of materials please consult the policiespage.oro.open.ac.ukSpectroscopic results from the Life in the Atacama (LITA) project 2004 field season. J.L. Piatek1, J.E.Moersch1, M. Wyatt2, M. Rampey1, N. A. Cabrol3,4, D. S. Wettergreen5, R. Whittaker5, E. A. Grin3,4, G. ChongDiaz6, C. Cockell7, P. Coppin8, J. M. Dohm9, G. Fisher10, A. N. Hock11, L. Marinangeli12, N. Minkley10, G. G. Ori12,A. Waggoner10, K. Warren-Rhodes3,4, S. Weinstein10, D. Apostolopoulos5, T. Smith5, M. Wagner5, K. Stubb5, G.Thomas13, and J. Glasgow13. 1Dept. of Earth and Planetary Sciences, Univ. of Tennessee, Knoxville, TN; 2ArizonaState University; 3NASA Ames SST.; 4SETI Institute; 5CMU Robotics Institute, Pittsburgh, PA; 6Univ. Catolica delNorte. Chile; 7British Antarctic Survey (BAS),UK; 8Eventscope, CMU, Pittsburgh; 9Univ. of Arizona. Tucson, AZ;10CMU MBIC, Pittsburgh; 11UCLA, CA. 12IRSPS, Pescara, Italy; 13GROK Laboratory, Univ. of Iowa, IAIntroduction: The Life in the Atacama (LITA)project includes rover field tests designed to look forlife in the arid environment of the Atacama Desert(Chile). Field instruments were chosen to help remoteobservers identify potential habitats and the presenceof life in these habitats, and included twospectrometers for help in identifying the mineralogyof the field sites.Two field trials were undertaken during the 2004field season. The remote science team had no priorknowledge of the local geology, and relied entirely onorbital images and rover-acquired data to makeinterpretations. Each field trial lasted approximatelyone week: the sites for these trials were in differentlocations, and are designated “Site B” and “Site C.”Instrumentation:  The field instrumentationincluded two spectrometers: one VNIR spectrometermounted on the rover, and one human operated TIRemission spectrometer. A second human-operatedVNIR spectrometer was also available in case ofdifficulties with the rover-mounted version; thissubstitution was only used at a single locale duringoperations, however. The rover-mounted VNIRspectrometer observes reflected light in thewavelength region from 0.5 – 2.5 µm: this wavelengthregion is very useful for identifying chlorophyllspectroscopically. Although the spectrometer ismounted next to the imager, the exact pointing isunknown.The TIR spectrometer measures emitted light, andthe useful wavelength range covers 8-13 µm. Thisinstrument is human-operated; however, the planningstrategy required that the remote science team treatthis instrument as if it were mounted on the rover.Orbital Results: Visible/near-infrared (VNIR)data from the IKONOS (Site B only) and ASTERinstruments were used to examine the photogeology ofthe field site, and in conjunction with elevation fromASTER DEMs to plan the daily traverse for the rover.ASTER thermal infrared (TIR) data has 5 bands inthe 8-12 µm wavelength region with a resolution of 90m /pixel. These images were used to try and identifythe regional mineralogy of each site. The data usedwere already processed to remove atmosphere and doa temperature-emissivity separation. The images wereprocessed in ENVI to identify spectral endmembers ineach image. These spectral endmembers were thencompared to reference library spectra (deconvolved toASTER bandpasses), and linear deconvolution used toidentify potential mineral or rock components in eachendmember. The resulting list of components was thenused in a linear deconvolution of the entire ASTERimage (along with a blackbody function). The resultwas an “endmember map,” which indicatedgraphically the percentage of each endmemberthroughout the image. At both sites, 3 majormineral/rock components were identified by thismethod: Site B endmembers were felsic volcanics,intermediate volcanics, and carbonates, while Site Cendmembers were albite, talc, and quartz. Gypsumwas present in a few areas at Site C, and was listed asa fourth “minor” endmember. The endmember mapfrom Site C is shown in Figure 1. These endmembermaps were created just prior to remote operations, andwere used to identify areas of interest (based onmineralogy), and to guide rover traverse planning.Rover Spectral Results: Both instruments usedduring remote ops proved useful in identifying themineralogy of the surface: however, no chlorophylldetections were made during either field trial. TheVNIR results were somewhat compromised byweather (when increasing humidity increased theatmospheric noise in the results), and by incompletecalibrations at some locales. In most locales at bothfield sites, the VNIR results appear to be clay mineralspectra (of various species): other VNIR resultssuggest sulfates or desert varnish.The TIR results were analyzed using lineardeconvolution, and are consistent with the clay resultsidentified in the VNIR. In addition, the TIR resultspicked up quantities of sulfates, zeolites, iron oxidesor sulfides, primary igneous minerals (pyroxenes andfeldspars), and quartz. Weather was also a factor inTIR acquisition.Discussion: Given the limited number of bands inthe ASTER TIR data, it is important to examine if thepre-ops conclusions (made using the ASTER derivedendmember maps) are consistent with the spectraacquired by the rover during the two field trials. It isnot possible, because of resolution, to directlyLunar and Planetary Science XXXVI (2005) 1563.pdfcompare the results, but the general conclusions madefrom the rover results can be used to better interpretthe ASTER results.At Site B, the endmembers identified wereintermediate volcanics, felsic volcanics, andcarbonates. While no carbonates were detected byrover spectrometers, there were no significantconcentrations of carbonates identified in the ASTERdata along the traverse path, so this identificationcannot be confirmed. In the case of the otherendmembers, a number of spectra suggested thepresence of feldspar and/or pyroxene at a particularlocale, which is consistent with the intermediatevolcanic endmember, although alteration minerals arepresent at all locales. It is possible that the felsicendmember is spectrally similar to clay minerals, andthis endmember should be altered intermediatevolcanics, rather than felsic volcanics. Theseendmembers are best revised as alteration productions(clays), altered intermediate volcanics, and carbonates(?).At Site C (see endmember map in Figure 1), themajor endmembers were talc, albite, and quartz: minorconcentrations of gypsum were also observed in theASTER TIR results. The remote science teamspecifically targeted an area of higher quartzconcentration, and results from that locale confirm thepresence of quartz. The talc endmember is potentiallyconsistent with the zeolites, micas, and clay mineralsidentified spectrally throughout the field area. Thealbite endmember is common throughout the image,and is spectrally similar to gypsum and other sulfates,although with a lower band depth. Based on the fieldresults, it appears that while the endmember spectrumis shaped most like albite, it is more likely that thespectrum represents particulate sulfates rather thanfeldspar. The endmembers at this site can be revised toclay minerals, quartz, and sulfates (particulate). Thepresence of quartz and sulfates at various locales areimportant detections for the identification of potentialhabitats.Implications: Even though chlorophyll was notdetected spectrally during the LITA 2004 field season,the spectral results are valuable for examining thelocal geology, and for pinpointing potential habitatswhere life may be present. The picture painted by therover results and the supporting orbital images suggestthat both sites consist of altered volcanic material,with more primary material present at Site B. Thesevolcanics have weathered over time to various clayminerals, and sulfate minerals have been deposited byprecipitation or evaporation. Improved targeting andinstrument calibration should lead to more conclusiveresults in the next field season.Figure 1: “Endmember map” for Site C, showing concentrations of endmembers: red – quartz; blue – clay, green –sulfate (particulate), as derived from ASTE RTIR result. The ‘landing ellipse’ and the rover traverse (beginning andending at ‘LS’) are shown in black (the traverse begins with a short eastward leg).Lunar and Planetary Science XXXVI (2005) 1563.pdf

Spectroscopic results from the Life in the Atacama (LITA) project 2004 field season

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Spectroscopic results from the Life in the Atacama (LITA) project 2004 field season

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