| Title | The limitations on organic detection in Mars-like soils by thermal volatilization- gas chromatography-MS and their implications for the Viking results |
| Author | Navarro-González, R.; Navarro, K.F.; de la Rosa, J.; Iñiguez, E.; Molina, P.; Miranda, L.D.; Morales, P.; Cienfuegos, E.; Coll, P.; Raulin, F.; Amils, R.; McKay, C.P. |
| Author Affil | Navarro-González, R., Universidad Nacional Autónoma de México, Laboratorio de Quimica de Plasmas y Estudios Planetarios, Mexico City, Mexico. Other: Université de Paris XII, France; Consejo Superior de Investigaciones Científicas, Spain; NASA, Ames Research Center |
| Source | Proceedings of the National Academy of Sciences of the United States of America, 103(44), p.16089-16094, . Publisher: National Academy of Sciences, Washington, DC, United States. ISSN: 0027-8424 |
| Publication Date | Oct. 31, 2006 |
| Notes | In English. Supplemental information/data is available in the online version of this article. 36 refs. GeoRef Acc. No: 297408 |
| Index Terms | Chile--Atacama Desert; Africa--Libyan Desert; Antarctica--McMurdo dry valleys; United States--Mojave Desert; Peru; Africa; Antarctica; aromatic hydrocarbons; astrobiology; Atacama Desert; benzene; C-13/C- 12; C/N; carbon; chemical analysis; Chile; detection; experimental studies; gas chromatograms; hydrocarbons; isotope ratios; isotopes; Libyan Desert; Mars; mass spectra; McMurdo dry valleys; Minas de Rio Tinto; Mojave Desert; natural analogs; nitrogen; organic compounds; Panoche Valley; planets; quantitative analysis; soils; South America; spectra; stable isotopes; terrestrial planets; thermal volatilization; United States; Victoria Land; Viking Program; volatilization |
| Abstract | The failure of Viking Lander thermal volatilization (TV) (without or with thermal degradation)-gas chromatography (GC)-MS experiments to detect organics suggests chemical rather than biological interpretations for the reactivity of the martian soil. Here, we report that TV-GC-MS may be blind to low levels of organics on Mars. A comparison between TV-GC-MS and total organics has been conducted for a variety of Mars analog soils. In the Antarctic Dry Valleys and the Atacama and Libyan Deserts we find 10-90 µg of refractory or graphitic carbon per gram of soil, which would have been undetectable by the Viking TV-GC-MS. In iron-containing soils (jarosites from Rio Tinto and Panoche Valley) and the Mars simulant (palogonite), oxidation of the organic material to carbon dioxide (CO2) by iron oxides and/or their salts drastically attenuates the detection of organics. The release of 50-700 ppm of CO2 by TV-GC-MS in the Viking analysis may indicate that an oxidation of organic material took place. Therefore, the martian surface could have several orders of magnitude more organics than the stated Viking detection limit. Because of the simplicity of sample handling, TV-GC-MS is still considered the standard method for organic detection on future Mars missions. We suggest that the design of future organic instruments for Mars should include other methods to be able to detect extinct and/or extant life. |
| URL | http://hdl.handle.net/10.1073/pnas.0604210103 |
| Publication Type | journal article |
| Record ID | 87499 |