Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Organic molecules revealed in Mars’s Bagnold Dunes by Curiosity’s derivatization experiment


The wet chemistry experiments on the Sample Analysis at Mars instrument on NASA’s Curiosity rover were designed to facilitate gas chromatography mass spectrometry analyses of polar molecules such as amino acids and carboxylic acids. Here we present the results of such a successful wet chemistry experiment on Mars on sand scooped from the Bagnold Dunes with the N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide derivatization agent. No amino-acid derivatives were detected. However, chemically derivatized benzoic acid and ammonia were detected. Mass spectra matching derivatized phosphoric acid and phenol were present, as were several nitrogen-bearing molecules and as yet unidentified high-molecular-weight compounds. The origin of these compounds, including those that may be internal to the Sample Analysis at Mars background, is examined. This derivatization experiment on Mars has expanded the inventory of molecules present in Martian samples and demonstrated a powerful tool to further enable the search for polar organic molecules of biotic or prebiotic relevance.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: The sample acquisition in context.
Fig. 2: Representative traces extracted from the EGA analysis (top) and chromatograms from the MXT-20 (centre) and Chirasil-β Dex (bottom) columns from selected m/z values or bands covering a range of masses1.
Fig. 3: SAM GCMS identification of benzoic acid derivatized compared with the SAM-like GC run of benzoic acid derivatized measured in laboratory.
Fig. 4
Fig. 5: 10 min section (23–33 min) of the chromatogram obtained with the spare Chirasil-β Dex column of the standard mixture of 22 amino acids derivatized with MTBSTFA-DMF.

Data availability

Data from the SAM experiments are archived in the Planetary Data System ( Data from the laboratory experiments can be found at: data are provided with this paper.


  1. Mahaffy, P. et al. The Sample Analysis at Mars investigation and instrument suite. Space Sci. Rev. 170, 401–478 (2012).

    ADS  Google Scholar 

  2. Szopa, C. et al. First detections of dichlorobenzene isomers and trichloromethylpropane from organic matter indigenous to Mars mudstone in Gale Crater, Mars: results from the Sample Analysis at Mars instrument onboard the Curiosity rover. Astrobiology 20, 292–306 (2020).

    ADS  Google Scholar 

  3. Freissinet, C. et al. Detection of long-chain hydrocarbons on Mars with the Sample Analysis at Mars (SAM) instrument. In Ninth International Conference on Mars abstr. no. 6123 (Lunar and Planetary Institute, 2019).

  4. Eigenbrode, J. L. et al. Organic matter preserved in 3-billion-year-old mudstones at Gale Crater, Mars. Science 360, 1096–1101 (2018).

    ADS  Google Scholar 

  5. Freissinet, C. et al. Organic molecules in the Sheepbed Mudstone, Gale Crater, Mars. J. Geophys. Res. Planets 120, 495–514 (2015).

    ADS  Google Scholar 

  6. Sunshine, D. Mars Science Laboratory CHIMRA: a device for processing powdered Martian samples. In Proceedings of the 40th Aerospace Mechanisms Symposium (NASA, 2010).

  7. Kminek, G. & Bada, J. L. The effect of ionizing radiation on the preservation of amino acids on Mars. Earth Planet. Sci. Lett. 245, 1–5 (2006).

    ADS  Google Scholar 

  8. Linstrom, P. J. & Mallard, W. G. The NIST Chemistry WebBook: a chemical data resource on the internet. J. Chem. Eng. Data 46, 1059–1063 (2001).

    Google Scholar 

  9. Benner, S. A., Devine, K. G., Matveeva, L. N. & Powell, D. H. The missing organic molecules on Mars. Proc. Natl Acad. Sci. USA 97, 2425–2430 (2000).

    ADS  Google Scholar 

  10. Millan, M. et al. Influence of calcium perchlorate on organics under SAM-like pyrolysis conditions: constraints on the nature of Martian organics. J. Geophys. Res. Planets 125, e2019JE006359 (2020).

    ADS  Google Scholar 

  11. Freissinet, C. et al. Benzoic acid as the preferred precursor for the chlorobenzene detected on Mars: insights from the unique Cumberland analog investigation. Planet. Sci. J. 1, 41 (2020).

    Google Scholar 

  12. Fox, A. C., Eigenbrode, J. L. & Freeman, K. H. Radiolysis of macromolecular organic material in Mars-relevant mineral matrices. J. Geophys. Res. Planets 124, 3257–3266 (2019).

    ADS  Google Scholar 

  13. Lewis, J. et al. Pyrolysis of oxalate, acetate, and perchlorate mixtures and the implications for organic salts on Mars. J. Geophys. Res. Planets 126, e2020JE006803 (2021).

    ADS  Google Scholar 

  14. Franz, H. et al. Indigenous and exogenous organics and surface–atmosphere cycling inferred from carbon and oxygen isotopes at Gale Crater. Nat. Astron. 4, 526–532 (2020).

    ADS  Google Scholar 

  15. Glavin, D. P. et al. Evidence for perchlorates and the origin of chlorinated hydrocarbons detected by SAM at the Rocknest aeolian deposit in Gale Crater. J. Geophys. Res. Planets 118, 1–18 (2013).

    Google Scholar 

  16. He, Y. et al. Influence of calcium perchlorate on the search for Martian organic compounds with MTBSTFA/DMF derivatization. Astrobiology 21, 1137–1156 (2021).

    ADS  Google Scholar 

  17. Stern, J. C. et al. The nitrate/(per)chlorate relationship on Mars. Geophys. Res. Lett. 44, 2643–2651 (2017).

    ADS  Google Scholar 

  18. Stern, J. C. et al. Evidence for indigenous nitrogen in sedimentary and aeolian deposits from the Curiosity rover investigations at Gale Crater, Mars. Proc. Natl Acad. Sci. USA 112, 4245–4250 (2015).

    ADS  Google Scholar 

  19. Glavin, D. P. et al. in Primitive Meteorites and Asteroids 205–271 (Elsevier, 2018).

  20. Sephton, M. A. et al. High molecular weight organic matter in Martian meteorite. Planet. Space Sci. 50, 711–716 (2002).

    ADS  Google Scholar 

  21. Callahan, M. P. et al. A search for amino acids and nucleobases in the Martian meteorite Roberts Massif 04262 using liquid chromatography–mass spectrometry. Meteorit. Planet. Sci. 48, 786–795 (2013).

    ADS  Google Scholar 

  22. Steele, A. et al. A reduced organic carbon component in Martian basalts. Science 337, 212–215 (2012).

    ADS  Google Scholar 

  23. Steele, A. et al. Organic synthesis on Mars by electrochemical reduction of CO2. Sci. Adv. 4, eaat5118 (2018).

    ADS  Google Scholar 

  24. Bishop, J. L. et al. Coordinated analyses of Antarctic sediments as Mars analog materials using reflectance spectroscopy and current flight-like instruments for CheMin, SAM and MOMA. Icarus 224, 309–325 (2013).

    ADS  Google Scholar 

  25. Siljeström, S. et al. Comparison of prototype and laboratory experiments on MOMA GCMS: results from the AMASE11 campaign. Astrobiology 14, 780–797 (2014).

    ADS  Google Scholar 

  26. Forni, O. et al. First detection of fluorine on Mars: implications for Gale Crater’s geochemistry. Geophys. Res. Lett. 42, 1020–1028 (2015).

    ADS  Google Scholar 

  27. Rampe, E. B. et al. Mineralogy and geochemistry of sedimentary rocks and eolian sediments in Gale Crater, Mars: a review after six Earth years of exploration with Curiosity. Geochemistry 80, 125605 (2020).

    Google Scholar 

  28. Berger, J. A. et al. Elemental composition and chemical evolution of geologic materials in Gale Crater, Mars: APXS results from Bradbury Landing to the Vera Rubin Ridge. J. Geophys. Res. Planets 125, e2020JE006536 (2020).

    ADS  Google Scholar 

  29. Forni, O. et al. Apatites in Gale Crater. In 51st Lunar and Planetary Science Conference abstr. no. 2192 (Lunar and Planetary Institute, 2020).

  30. Blank, J. G. et al. Detection of phosphorus by ChemCam in Gale Crater. In 46th Lunar and Planetary Science Conference abstr. no. 2850 (Lunar and Planetary Institute, 2015).

  31. O’Connell‐Cooper, C. et al. APXS‐derived chemistry of the Bagnold dune sands: comparisons with Gale Crater soils and the global Martian average. J. Geophys. Res. Planets 122, 2623–2643 (2017).

    ADS  Google Scholar 

  32. Carrillo-Sánchez, J. D. et al. Injection of meteoric phosphorus into planetary atmospheres. Planet. Space Sci. 187, 104926 (2020).

    Google Scholar 

  33. Ritson, D. J., Mojzsis, S. J. & Sutherland, J. D. Supply of phosphate to early Earth by photogeochemistry after meteoritic weathering. Nat. Geosci. 13, 344–348 (2020).

    ADS  Google Scholar 

  34. Navarro-González, R. et al. Search of phosphine in the evolved gases from hypophosphite/phosphite minerals in lacustrine sedimentary rocks at Gale Crater by the Sample Analysis at Mars. In 52nd Lunar and Planetary Science Conference abstr. no. 2548 (Lunar and Planetary Institute, 2021).

  35. Miller, K. E. et al. Evaluation of the Tenax trap in the Sample Analysis at Mars instrument suite on the Curiosity rover as a potential hydrocarbon source for chlorinated organics detected in Gale Crater. J. Geophys. Res. Planets 120, 1446–1459 (2015).

    ADS  Google Scholar 

  36. Buch, A. et al. Role of the Tenax® adsorbent in the interpretation of the EGA and GC‐MS analyses performed with the Sample Analysis at Mars in Gale Crater. J. Geophys. Res. Planets 124, 2819–2851 (2019).

    ADS  Google Scholar 

  37. Eigenbrode, J. L. et al. Sample Chemistry Revealed by TMAH-evolved gas analysis: Results from the first In situ thermochemolysis experiment at Gale Crater, Mars. In AGU Fall Meeting 2020 (American Geophysical Union, 2020).

  38. Williams, A. et al. The search for fatty acids on Mars: Results from the first In situ thermochemolysis experiment at Gale Crater, Mars. In AGU Fall Meeting 2020 (American Geophysical Union, 2020).

  39. Goesmann, F. et al. The Mars Organic Molecule Analyzer (MOMA) instrument: characterization of organic material in Martian sediments. Astrobiology 17, 655–685 (2017).

    ADS  Google Scholar 

  40. Rampe, E. B. et al. Sand mineralogy within the Bagnold Dunes, Gale Crater, as observed in situ and from orbit. Geophys. Res. Lett. 45, 9488–9497 (2018).

    ADS  Google Scholar 

  41. Rampe, E. B. et al. Mineralogy of aeolian Sand in Gale Crater, Mars. In 49th Lunar and Planetary Science Conference abstr. no. 1654 (Lunar and Planetary Institute, 2018).

  42. Stern, J. C. et al. Major volatiles evolved from eolian materials in Gale Crater. Geophys. Res. Lett. 45, 10240–10248 (2018).

    ADS  Google Scholar 

  43. Stalport, F. et al. The influence of mineralogy on recovering organic acids from Mars analogue materials using the ‘one-pot’ derivatization experiment on the Sample Analysis at Mars (SAM) instrument suite. Planet. Space Sci. 67, 1–13 (2012).

    ADS  Google Scholar 

  44. Williams, A. J. et al. Recovery of fatty acids from mineralogic Mars analogs by TMAH thermochemolysis for the Sample Analysis at Mars wet chemistry experiment on the Curiosity rover. Astrobiology 19, 522–546 (2019).

    ADS  Google Scholar 

  45. Bart, M. Electron Impact Ionization: Measurements of Absolute Cross-sections and Cross-beam Studies PhD thesis, Univ. Canterbury (2003).

  46. Harrison, A., Jones, E., Gupta, S. & Nagy, G. Total cross sections for ionization by electron impact. Can. J. Chem. 44, 1967–1973 (1966).

    Google Scholar 

  47. Alberti, R., Genoni, M., Pascual, C. & Vogt, J. Elektronenstoss ionisationsquerschnitte von organischen molekuelen. Int. J. Mass Spectrom. Ion. Process. 14, 89–98 (1974).

    ADS  Google Scholar 

  48. Lampe, F., Franklin, J. & Field, F. Cross sections for ionization by electrons. J. Am. Chem. Soc. 79, 6129–6132 (1957).

    Google Scholar 

  49. Millan, M. et al. Performance of the SAM gas chromatographic columns under simulated flight operating conditions for the analysis of chlorohydrocarbons on Mars. J. Chromatogr. A 1598, 183–195 (2019).

    Google Scholar 

  50. Millan, M. et al. In situ analysis of Martian regolith with the SAM experiment during the first Mars year of the MSL mission: identification of organic molecules by gas chromatography from laboratory measurements. Planet. Space Sci. 129, 88–102 (2016).

    ADS  Google Scholar 

  51. de Campos, M. C. V., Oliveira, E. C., Sanches Filho, P. J., Piatnicki, C. M. S. & Caramão, E. B. Analysis of tert-butyldimethylsilyl derivatives in heavy gas oil from Brazilian naphthenic acids by gas chromatography coupled to mass spectrometry with electron impact ionization. J. Chromatogr. A 1105, 95–105 (2006).

    Google Scholar 

  52. John, W. P. S., Rughani, J., Green, S. A. & McGinnis, G. D. Analysis and characterization of naphthenic acids by gas chromatography–electron impact mass spectrometry of tert-butyldimethylsilyl derivatives. J. Chromatogr. A 807, 241–251 (1998).

    Google Scholar 

  53. Pavlov, A. A., Vasilyev, G., Ostryakov, V. M., Pavlov, A. K. & Mahaffy, P. Degradation of the organic molecules in the shallow subsurface of Mars due to irradiation by cosmic rays. Geophys. Res. Lett. 39, L13202 (2012).

Download references


We thank the Mars Science Laboratory and SAM engineering and scientific teams for their support and insightful discussions, F. J. Calef for providing Fig. 1a, R. Sullivan for his advice and contribution to Fig. 1 and P.-Y. Meslin for his insights on phosphorus detections by the ChemCam instrument. M.M. and S.S.J. acknowledge funding from the NASA-GSFC grant NNX17AJ68G: ‘Using Organic Molecule Detections in Mars Analog Environments to Interpret the Results of the SAM Investigation on the MSL Mission’. R.N.-G. acknowledges the Universidad Nacional Autónoma de México (UNAM: PAPIIT IN111619 and PAPIME PE102319) for financial support. We also acknowledge the financial support provided by the Centre National d’Etudes Spatiales (CNES), related to SAM and Mars Science Laboratory.

Author information

Authors and Affiliations



M.M. processed the data, calculated and interpreted GCMS data and wrote most of the manuscript and supplementary material under the supervision of S.S.J. and P.R.M. S.T. and C.A.M. prepared and developed the wet experiment using the SAM Testbed replica located at NASA-Goddard Space Flight Center and performed the SAM flight pyrolysis and derivatization GCMS experiments on Mars. M.M. and A.S. performed SAM-like laboratory analysis in support of flight data. J.C.S. and B.S interpreted EGA data. P.R.M., S.S.J., J.Y.B., A.B., J.P.D., J.L.E., C.F., D.P.G., R.N.-G., C.S., A.J.W., R.H.W. and G.M.W. participated in data processing, discussion and interpretation of results and/or manuscript editing.

Corresponding author

Correspondence to M. Millan.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Astronomy thanks Olivier Forni, Laura Crossey and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 SAM instrument suite (A), Sample Manipulation System (B), picture of the flight derivatization cup (C) and example of derivatization reaction (D).

(a) SAM suite showing the gas chromatograph (GC), the quadrupole mass spectrometer (MS) and the sample carousel. (b) Sample Manipulation System (SMS) holding the 74 cups in the sample carousel, including both quartz and metal cups. (c) Picture of a flight derivatization metal cup (left) and its outer foil cap (bottom left), and a schematic (right) where the outer reservoir containing the MTBSTFA-DMF and pyrene standard and the inner compartment isolated by a welded metal foil containing the dried DL-3-fluorovaline internal standard are labeled. (D) Example of derivatization reaction of an amino acid with MTBSTFA: the labile hydrogen atom of glycine OH function is substituted by the tert-butyldimethylsilyl group of the MTBSTFA reagent. The products of the reaction are N,O-bis(dimethyl-t-butylsilyl)-glycine (Glycine, di t-BDMS) and 2,2,2-trifluoromethylacetamide (TFMA). Adapted from Mahaffy et al.1.

Source data

Extended Data Fig. 2 Temperature cuts sent to the hydrocarbon trap.

The orange bands highlight the temperature cuts that were sent to the hydrocarbon (HC) trap during pyrolysis. To avoid the saturation of the MTBSTFA-DMF by-products, illustrated here with bi-silylated water (BSW) and N-methyl-2,2,2-trifluoroacetamide (TFMA), 2.5% of the gas was sent from 0–100 °C, 7% from 100–250 °C, and 50% from the remaining portion of the pyrolysis ramp.

Source data

Extended Data Fig. 3 Chromatogram extracted from the pyrolysis–GCMS analysis of the Ogunquit beach sample (OG3).

The two IT flashes: IT 1 and IT 2, are represented by blue arrows at activation times: 0 and 18.3 min, respectively. Bands 4–6 and 8–13 are plotted and correspond to the sum of the ions between the range of given masses (for example, band 4 is the sum of the ions from m/z 45 to 65). The major ion mass fragments of the main chlorohydrocarbons detected have also been extracted to facilitate their identification. The main labeled peaks are: 1) m/z 50: chloromethane, 2) CS2, 3) m/z 84: dichloromethane, 4–5) m/z 90: 1- and 3-chloromethylpropene isomers, 6) m/z 83: trichloromethane, 7) t-BDMS-F, 8) benzene, 9) toluene, 10) TFMA coeluted with Cl-t-BDMS, 11) m/z 112: chlorobenzene, 12) bi-silylated water, and 13) co-elution of all the previous molecules that come out a second time after the second IT flash. SO2 was also detected and co-elutes with chloromethane at 3.2 minutes but is not represented due to the saturation of its peak.

Source data

Extended Data Fig. 4 Dioxygen released from the dry (OG3-red) and wet (OG4-blue) OG sample.

Thermograms of evolved gas from the OG sample comparing the dioxygen released from the dry (OG3-red) and wet (OG4-blue) sample.

Source data

Extended Data Fig. 5 Derivatized ammonia identified by GCMS.

(Top) GCMS identification of derivatized ammonia eluted at 17.3 min in the OG flight chromatogram (a) compared to the laboratory GC analysis of derivatized ammonia analysed in SAM-like operational conditions with the Chirasil-β Dex column (b) detected at 18.8 min. The OG chromatogram is compared to the follow-up analysis from which the signal was increased by 10. The OG follow-up analysis was performed with a 5 °C/min ramp compared to the 10 °C/min ramp of the OG analysis, thus, t-BDMS ammonia eluted at 25.1 min in the follow-up compared to the 17.3 min in the OG analysis. To allow the comparison of both peaks in one figure, the follow-up chromatogram was shifted of 7.8 min to match both flight-retention times. Because the m/z 146 major ion mass fragment of derivatized NH3 was under sampled over the course of the peak elution, its intensity is lower compared to the m/z 188 second major ion mass fragment and what it should be from the NIST spectrum. The m/z 188, second major ion mass fragment of derivatized ammonia, was then chosen and extracted from the TIC for all three chromatograms. (Bottom) Mass spectrum of derivatized ammonia extracted from the SAM chromatogram (red) compared to the mass spectrum extracted from the NIST Mass Spectral Database (blue). A fraction of the m/z 73 and 148 from the SAM mass spectra belong to the mass spectra of bi-silylated water (this is why they have higher intensities in flight compared to the NIST intensities).

Source data

Extended Data Fig. 6 Percentages of the main category of compounds that were extracted relative to the total number of compounds that were extracted from the MXT-20, Chirasil-β Dex and Chirasil-β Dex follow-up analyses.

These percentages are a rough estimation of the compounds that we were able to extract and with co-elutions represent a lower limit of the molecules present in the GCMS chromatogram. This is especially true for the MXT-20 and Chirasil-β Dex columns where the MTBSTFA-DMF saturation plus related by-products are likely obscuring the signal from other molecules.

Source data

Extended Data Fig. 7 Examples of mass spectra of molecules detected in the OG and follow-up analyses.

a. Hexadecamethyl-octasiloxane, a common product from column bleeding was detected in the Chirasil-β Dex chromatogram, b. Dimethylaminoacetonitrile, N-bearing organic detected in the Chirasil-β Dex follow-up analysis, c. 2,2,2-trifluoro-N-methylacetamide, a common MTBSTFA by-product detected in MXT-20, Chirasil-β Dex and follow-up analyses, d. Bis tert-butyldimethylsilyl-ammonia, N-bearing MTBSTFA by-product detected in the Chirasil-β Dex and follow-up analyses.

Extended Data Fig. 8 A 32 min section (23–55 minutes) of the chromatogram of the follow-up analysis obtained with the spare Chirasil-β Dex column where no amino acids were injected.

As shown above, derivatized methionine, serine, threonine, and phenylalanine would be detectable in the first follow-up analysis, and derivatized aspartic acid and hydroxyproline would be detectable in the second follow-up analysis within the standard operating conditions used on Mars for the Chirasil-β Dex column. Derivatized phenylalanine eluting after 49 min of the first follow-up run (represented in red dashed dots) could be detectable if the MS signal continued to be recorded while the column cooled down after the end of the follow-up run. The temperature of the Chirasil-β Dex column is represented in green; it reached ~150 °C at ~56 min of the GC run.

Source data

Supplementary information

Supplementary Information

Supplementary Table 1.

Source data

Source Data Fig. 2

Relevant masses and bands (ranges of masses) exported from Igor 8.

Source Data Fig. 3

Raw Xcalibur GC data and relevant masses exported from Igor 8.

Source Data Fig. 4

Relevant masses and bands (ranges of masses) exported from Igor 8.

Source Data Fig. 5

Raw Xcalibur GC data.

Source Data Extended Data Fig. 1

ChemSketch file used for Extended Data Fig. 1.

Source Data Extended Data Fig. 2

Relevant masses and bands (ranges of masses) exported from Igor 8.

Source Data Extended Data Fig. 3

Relevant masses and bands (ranges of masses) exported from Igor 8.

Source Data Extended Data Fig. 4

Raw EGA data and temperature.

Source Data Extended Data Fig. 5

Raw and processed Xcalibur GC data and relevant masses exported from Igor 8.

Source Data Extended Data Fig. 6

Statistical source data.

Source Data Extended Data Fig. 8

Raw Xcalibur GC data.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Millan, M., Teinturier, S., Malespin, C.A. et al. Organic molecules revealed in Mars’s Bagnold Dunes by Curiosity’s derivatization experiment. Nat Astron 6, 129–140 (2022).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing