Examinando por Autor "Sutter, Brad"

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A Review of Sample Analysis at Mars-Evolved Gas Analysis Laboratory Analog Work Supporting the Presence of Perchlorates and Chlorates in Gale Crater, Mars
(Multidisciplinary Digital Publishing Institute (MDPI), 2021-04-20) Clark, J.; Sutter, Brad; Douglas Archer, P.; Ming, D.; Elizabeth Rampe; McAdam, A. C.; Navarro González, R.; Eigenbrode, Jennifer L.; Glavin, D.; Zorzano, María-Paz; Martín Torres, Javier; Morris, Richard V.; Tu, V.; Ralston, S. J.; Mahaffy, Paul R.; Agencia Estatal de Investigación (AEI)
The Sample Analysis at Mars (SAM) instrument on the Curiosity rover has detected evidence of oxychlorine compounds (i.e., perchlorates and chlorates) in Gale crater, which has implications for past habitability, diagenesis, aqueous processes, interpretation of in situ organic analyses, understanding the martian chlorine cycle, and hazards and resources for future human exploration. Pure oxychlorines and mixtures of oxychlorines with Mars-analog phases have been analyzed for their oxygen (O2) and hydrogen chloride (HCl) releases on SAM laboratory analog instruments in order to constrain which phases are present in Gale crater. These studies demonstrated that oxychlorines evolve O2 releases with peaks between ~200 and 600 °C, although the thermal decomposition temperatures and the amount of evolved O2 decrease when iron phases are present in the sample. Mg and Fe oxychlorines decompose into oxides and release HCl between ~200 and 542 °C. Ca, Na, and K oxychlorines thermally decompose into chlorides and do not evolve HCl by themselves. However, the chlorides (original or from oxychlorine decomposition) can react with water-evolving phases (e.g., phyllosilicates) in the sample and evolve HCl within the temperature range of SAM (<~870 °C). These laboratory analog studies support that the SAM detection of oxychlorine phases is consistent with the presence of Mg, Ca, Na, and K perchlorate and/or chlorate along with possible contributions from adsorbed oxychlorines in Gale crater samples.
Restringido
Background levels of methane in Mars’ atmosphere show strong seasonal variations
(Science, 2018-06-08) Webster, Christopher R.; Mahaffy, Paul R.; Atreya, Sushil K.; Moores, John E.; Flesch, Gregory J.; Malespin, Charles A.; McKay, Christopher P.; Martínez, Germán M.; Smith, Christina L.; Martín Torres, Javier; Gómez Elvira, J.; Zorzano, María-Paz; Wong, Michael H.; Trainer, Melissa G.; Steele, Andrew; Archer, Doug; Sutter, Brad; Coll, Patrice J.; Freissinet, Caroline; Meslin, Pierre-Yves; Gough, Raina V.; House, Christopher H.; Pavlov, Alexander; Eigenbrode, Jennifer L.; Glavin, Daniel P.; Pearson, John C.; Keymeulen, Didier; Christensen, Lance E.; Schwenzer, Susanne P.; Navarro González, R.; Pla García, J.; Rafkin, Scot C. R.; Vicente Retortillo, Álvaro; Kahanpää, H.; Viúdez Moreiras, Daniel; Smith, Michael D.; Harri, Ari-Matti; Genzer, María; Hassler, Donald M.; Lemmon, M. T.; Crisp, Joy; Sander, Stanley P.; Zurek, Richard W.; Vasavada, Ashwin R.; National Aeronautics and Space Administration (NASA)
Variable levels of methane in the martian atmosphere have eluded explanation partly because the measurements are not repeatable in time or location. We report in situ measurements at Gale crater made over a 5-year period by the Tunable Laser Spectrometer on the Curiosity rover. The background levels of methane have a mean value 0.41 ± 0.16 parts per billion by volume (ppbv) (95% confidence interval) and exhibit a strong, repeatable seasonal variation (0.24 to 0.65 ppbv). This variation is greater than that predicted from either ultraviolet degradation of impact-delivered organics on the surface or from the annual surface pressure cycle. The large seasonal variation in the background and occurrences of higher temporary spikes (~7 ppbv) are consistent with small localized sources of methane released from martian surface or subsurface reservoirs.