2 Peak 1 Peak 2 Temperature ( o C )
1
Figure 6. Release of m/z 30 versus temperature from the blank and Rocknest samples as measured by SAM. Peak 1 was identified as NO using the NIST database, which reports the ratio of (m/z 14)/(m/z 30) in NO as 0.075. Other plausible contributions to m/z 30 include an isotopologue of CO, 12 C 18 O. Surprisingly the evolution of m/z 30 in the Rocknest samples is well below the expected thermal decomposition of nitrates. Temperature ( o C) 200 400 600 800 Mass/charge 30 (cps) 10 5 Blank Sample 1 Sample 2 Sample 3 Sample 4 Peak 1 Peak 2 Peak 3 POSSIBLE DETECTION OF NITRATES ON MARS BY THE SAMPLE ANALYSIS AT MARS (SAM) INSTRUMENT R. Navarro-González 1 , J. Stern 2 , B. Sutter 3 , D. Archer 3 , A. McAdam 2 , H.B. Franz 2 , C.P. McKay 4 , P. Coll 5 , M. Cabane 6 , D.W. Ming 3 , F. Raulin 5 , A.E. Brunner 2 , D. Glavin 2 , J.L. Eigenbrode 2 , J.H. Jones 3 , C. Freissinet 2 , L. Leshin 7 , M. Wong 8 , S. Atreya 8 , J.J. Wray 9 , A. Steele 10 , A. Buch 11 , B.D. Prats 2 , C. Szopa 6 , D. Coscia 6 , S. Teinturier 6 , P. Conrad 2 , P. Mahaffy 2 , F.J. Martín-Torres 12 , M.-P. Zorzano-Mier 12 , J.P. Grotzinger 13 , and the MSL Science Team 1 Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico, 2 NASA Goddard Space Flight Center, Greenbelt, MD 20771, 3 NASA Johnson Space Center, Houston TX 77058, 4 NASA Ames Research Center, Moffett Field, CA 94035, 5 LISA, Univ. Paris-Est Créteil, Univ. Denis Diderot & CNRS, 94000 Créteil, France, 6 LATMOS, Univ. Pierre et Marie Curie, Univ. Versailles Saint-Quentin & CNRS, 75005 Paris, France, 7 Rensselaer Polytechnic Institute, Troy, NY 12180, 8 University of Michigan, Ann Arbor, MI 48109, 9 Georgia Institute of Technology, Atlanta, GA 30332, 10 Geophysical Laboratory, Washington, DC 20015, 11 Ecole Centrale Paris, LGPM, 92295 Châtenay-Malabry, France, 12 Centro de Astrobiología (CSIC-INTA) Carretera de Ajalvir km. 4, 28850 Torrejón de Ardoz, Madrid, Spain, 13 California Institute of Technology, Pasadena, CA 91125. INTRODUCTION Planetary models suggest that nitrogen was abundant in the early Martian atmosphere as dinitrogen (N 2 ). However, it has been lost by sputtering and photochemical loss to space [1, 2], impact erosion [3], and chemical oxidation to nitrates [4]. Nitrates, produced early in Mars’ history, are later decomposed back into N 2 by the current impact flux [5], making possible a nitrogen cycle on Mars. It is estimated that a layer of about 3 m of pure NaNO 3 should be distributed globally on Mars [5]. Nitrates are a fundamental source for nitrogen to terrestrial microorganisms. Therefore, the detection of soil nitrates is important to assess habitability in the Martian environment. The only previous mission that was designed to search for soil nitrates was the Phoenix mission but was unable to detect evolved N-containing species by TEGA and the MECA WCL due to the presence of perchlorate [6]. Nitrates have been tentatively identified in the Nakhla meteorite [7]. The purpose of this work is to determine if nitrates were detected in the first solid sample (Rocknest) in Gale Crater examined by the SAM instrument. SAMPLING LOCATION Figure 1. This HiRISE base map shows the Curiosity Rover’s traverse at Gale crater since landing at Bradbury on August 5, 2012 to Sol 130 (Dec. 17, 2012). The Rover parked between sols 60-100, at a location called “Rocknest,” where it scooped and analyzed windblown sand (Image credit: NASA/JPL-Caltech/Univ. of Arizona) . Figure 2. The drift consists of sand trapped on the downwind side of a group of dark cobbles that the team named Rocknest. This mosaic of 55 images from the Mars Hand Lens Imager (MAHLI) shows the first four of five places from which the rover's scoop obtained sand to clean the sample handling and processing system. The fifth scooped material was ultimately delivered to SAM (Image credit: NASA/JPL-Caltech/MSSS). MATERIALS AND METHODS Figure 4. The Sample Analysis at Mars Instrument (Image credit: NASA/JPL-Caltech). Blank and Rocknest (< 150 μm) samples were heated to ~840C at a rate of 35C/min under a He carrier gas flow rate of 1.5 cm 3 /min and at an oven pressure of ~30 mbar. Evolved nitric oxide (e.g., m/z 30) was analyzed directly by electron impact quadrupole mass spectrometry (QMS). Figure 5. UNAM Thermal analyzer (Netzsch STA 449 F1 Jupiter Simultaneous TG/DSC) coupled to Mass Spectrometry (Netzsch QMS 403 C Aeolos) used in support for interpretation of SAM DATA. Mixtures of perchlorates, nitrates, and ammonium salts were heated upto 1200C at a rate of 20C/min under a He or N 2 carrier gas flow rate of 20 cm 3 /min and at an oven pressure of 1000 mbar. 50% NaNO 10% NaNO 3 +90% Mg(ClO 4 ) 2 Temperature ( o C ) 200 400 600 800 Nitric oxide (Ion current) 10 -12 10 -11 10 -10 10 -9 100% NaNO 3 50% NaNO 3 + 50% Mg(ClO 4 ) 2 10% NaNO 3 + 90% Mg(ClO 4 ) 2 Figure 6. Effect of magnesium perchlorate on the thermal stability of Na-nitrate in laboratory experiments. The decomposition of nitrates is enhanced as more perchlorate is added to the mixture. No effect is observed for Na-perchlorate. Figure 7. Thermal stability of different (10%) nitrates (Left panel) or (10%) ammonium salts (Right panel) in the presence of (90%) Mg- perchlorate in laboratory experiments. Similar results are obtained for Ca-perchlorate but curves move to higher temperatures by about 50C. 200 400 600 800 10 -12 10 -11 10 -10 10 -9 NH 4 HCO 3 NH 4 Cl NH 4 NO 3 (NH 4 ) 2 SO 4 Temperature ( o C ) 200 400 600 800 Nitric oxide (Ion current) 10 -12 10 -11 10 -10 10 -9 NaNO 3 KNO 3 Mg(NO 3 ) 2 Ca(NO 3 ) 2 CONCLUSIONS 1. Laboratory studies operating at higher atmospheric pressure than SAM show that Mg-, Ca-, Na-, and K-nitrates decompose from 330C to 600C (Figure 7, Left panel), and from 360C to 650C (data not shown), in the presence of Mg- and Ca-perchlorate, respectively. Under these conditions Mg- or Ca-nitrates cannot explain the release of NO (peak 1 in Figure 6) at the Rocknest data. However, the release of NO could potentially decrease at lower oven pressures as those used by SAM. 2. The decomposition of ammonium nitrate and subsequent combustion of ammonia to NO in the presence of perchlorates is currently the best interpretation for peak 1 (Figure 6) in the Rocknest data. 3. Combustion of MTBSTFA (known to be present in the SAM system) can contribute partially or significantly to peak 1 (Figure 6) [8, 9]. 4. Further work is underway to fully understand the release of NO in the Rocknest samples and the UNAM thermal analyzer is being adapted to operate under SAM conditions. REFERENCES [1] Luhmann, J.G. et al. (1992), GRL, 19, 2151-2154. [2] Jakosky, B.M. et al. (1994), Icarus, 111, 271–288. [3] Melosh, H.J. & Vickery, A.M. (1989), Nature, 338, 487–489. [4] Mancinelli, R.L. & McKay, C.P. (1988), Origins Life 18, 311–325. [5] Manning, C.V. et al. (2008), Icarus, 197, 60–64. [6] Hecht, M. H. et al. (2009), Science, 32, 64–67. [7] Grady, M.M. et al. (1995), J. Geophys. Res. 100, 5449. [8] Buch, A., et al., this meeting. [9] Freissinet, C. et al., this meeting.
Transcript of 2 Peak 1 Peak 2 Temperature ( o C )
RESULTS AND DISCUSSION Figure 6. Release of m/z 30 versus temperature from the blank and Rocknest samples as measured by SAM. Peak 1 was identified as NO using the NIST database, which reports the ratio of (m/z 14)/(m/z 30) in NO as 0.075. Other plausible contributions to m/z 30 include an isotopologue of CO, 12C18O. Surprisingly the evolution of m/z 30 in the Rocknest samples is well below the expected thermal decomposition of nitrates.
Temperature (oC)
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POSSIBLE DETECTION OF NITRATES ON MARS BY THE SAMPLE ANALYSIS AT MARS (SAM) INSTRUMENT R. Navarro-González1, J. Stern2, B. Sutter3, D. Archer3, A. McAdam2, H.B. Franz2, C.P. McKay4, P. Coll5, M. Cabane6, D.W. Ming3, F. Raulin5, A.E. Brunner2,
D. Glavin2, J.L. Eigenbrode2, J.H. Jones3, C. Freissinet2, L. Leshin7, M. Wong8, S. Atreya8, J.J. Wray9, A. Steele10, A. Buch11, B.D. Prats2, C. Szopa6, D. Coscia6, S. Teinturier6, P. Conrad2, P. Mahaffy2, F.J. Martín-Torres12, M.-P. Zorzano-Mier12, J.P. Grotzinger13, and the MSL Science Team
1Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico, 2NASA Goddard Space Flight Center, Greenbelt, MD 20771, 3NASA Johnson Space Center, Houston TX 77058, 4NASA Ames Research Center, Moffett Field, CA 94035, 5LISA, Univ. Paris-Est Créteil, Univ. Denis Diderot & CNRS, 94000 Créteil, France, 6LATMOS, Univ. Pierre et Marie Curie, Univ. Versailles Saint-Quentin & CNRS, 75005 Paris, France, 7Rensselaer Polytechnic Institute, Troy, NY 12180,
8University of Michigan, Ann Arbor, MI 48109, 9Georgia Institute of Technology, Atlanta, GA 30332, 10Geophysical Laboratory, Washington, DC 20015, 11Ecole Centrale Paris, LGPM, 92295 Châtenay-Malabry, France, 12Centro de Astrobiología (CSIC-INTA) Carretera de Ajalvir km. 4, 28850 Torrejón de Ardoz, Madrid, Spain, 13California Institute of Technology, Pasadena, CA 91125.
INTRODUCTION Planetary models suggest that nitrogen was abundant in the early Martian atmosphere as dinitrogen (N2). However, it has been lost by sputtering and photochemical loss to space [1, 2], impact erosion [3], and chemical oxidation to nitrates [4]. Nitrates, produced early in Mars’ history, are later decomposed back into N2 by the current impact flux [5], making possible a nitrogen cycle on Mars. It is estimated that a layer of about 3 m of pure NaNO3 should be distributed globally on Mars [5]. Nitrates are a fundamental source for nitrogen to terrestrial microorganisms. Therefore, the detection of soil nitrates is important to assess habitability in the Martian environment. The only previous mission that was designed to search for soil nitrates was the Phoenix mission but was unable to detect evolved N-containing species by TEGA and the MECA WCL due to the presence of perchlorate [6]. Nitrates have been tentatively identified in the Nakhla meteorite [7]. The purpose of this work is to determine if nitrates were detected in the first solid sample (Rocknest) in Gale Crater examined by the SAM instrument.
SAMPLING LOCATION Figure 1. This HiRISE base map shows the Curiosity Rover’s traverse at Gale crater since landing at Bradbury on August 5, 2012 to Sol 130 (Dec. 17, 2012). The Rover parked between sols 60-100, at a location called “Rocknest,” where it scooped and analyzed windblown sand (Image credit: NASA/JPL-Caltech/Univ. of Arizona) . Figure 2. The drift consists of sand trapped on the downwind side of a group of dark cobbles that the team named Rocknest. This mosaic of 55 images from the Mars Hand Lens Imager (MAHLI) shows the first four of five places from which the rover's scoop obtained sand to clean the sample handling and processing system. The fifth scooped material was ultimately delivered to SAM (Image credit: NASA/JPL-Caltech/MSSS).
MATERIALS AND METHODS Figure 4. The Sample Analysis at Mars Instrument (Image credit: NASA/JPL-Caltech). Blank and Rocknest (< 150 μm) samples were heated to ~840C at a rate of 35C/min under a He carrier gas flow rate of 1.5 cm3/min and at an oven pressure of ~30 mbar. Evolved nitric oxide (e.g., m/z 30) was analyzed directly by electron impact quadrupole mass spectrometry (QMS). Figure 5. UNAM Thermal analyzer (Netzsch STA 449 F1 Jupiter Simultaneous TG/DSC) coupled to Mass Spectrometry (Netzsch QMS 403 C Aeolos) used in support for interpretation of SAM DATA. Mixtures of perchlorates, nitrates, and ammonium salts were heated upto 1200C at a rate of 20C/min under a He or N2 carrier gas flow rate of 20 cm3/min and at an oven pressure of 1000 mbar.
100% NaNO3
50% NaNO3 +50% Mg(ClO4)2
10% NaNO3 +90% Mg(ClO4)2
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100% NaNO3
50% NaNO3 + 50% Mg(ClO4)2
10% NaNO3 + 90% Mg(ClO4)2
Figure 6. Effect of magnesium perchlorate on the thermal stability of Na-nitrate in laboratory experiments. The decomposition of nitrates is enhanced as more perchlorate is added to the mixture. No effect is observed for Na-perchlorate. Figure 7. Thermal stability of different (10%) nitrates (Left panel) or (10%) ammonium salts (Right panel) in the presence of (90%) Mg-perchlorate in laboratory experiments. Similar results are obtained for Ca-perchlorate but curves move to higher temperatures by about 50C.
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NH4ClNH4NO3
(NH4)2SO4
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CONCLUSIONS 1. Laboratory studies operating at higher atmospheric pressure than
SAM show that Mg-, Ca-, Na-, and K-nitrates decompose from 330C to 600C (Figure 7, Left panel), and from 360C to 650C (data not shown), in the presence of Mg- and Ca-perchlorate, respectively. Under these conditions Mg- or Ca-nitrates cannot explain the release of NO (peak 1 in Figure 6) at the Rocknest data. However, the release of NO could potentially decrease at lower oven pressures as those used by SAM.
2. The decomposition of ammonium nitrate and subsequent combustion of ammonia to NO in the presence of perchlorates is currently the best interpretation for peak 1 (Figure 6) in the Rocknest data.
3. Combustion of MTBSTFA (known to be present in the SAM system) can contribute partially or significantly to peak 1 (Figure 6) [8, 9].
4. Further work is underway to fully understand the release of NO in the Rocknest samples and the UNAM thermal analyzer is being adapted to operate under SAM conditions.
REFERENCES [1] Luhmann, J.G. et al. (1992), GRL, 19, 2151-2154. [2] Jakosky, B.M. et al.
(1994), Icarus, 111, 271–288. [3] Melosh, H.J. & Vickery, A.M. (1989), Nature, 338, 487–489. [4] Mancinelli, R.L. & McKay, C.P. (1988), Origins Life 18, 311–325. [5] Manning, C.V. et al. (2008), Icarus, 197, 60–64. [6] Hecht, M. H. et al. (2009), Science, 32, 64–67. [7] Grady, M.M. et al. (1995), J. Geophys. Res. 100, 5449. [8] Buch, A., et al., this meeting. [9] Freissinet, C. et al., this meeting.
