The Sirens of Mars

by Sarah Stewart Johnson

  SMITH TOLD THE PRESS Andrea Thompson, “Phoenix Mars Lander Found Liquid Water, Some Scientists Think,” Space (March 10, 2009).

  ANOTHER WHITE PATCH P. H. Smith, L. K. Tamppari, R. E. Arvidson, D. Bass, D. Blaney, William V. Boynton, A. Carswell, et al., “H2O at the Phoenix Landing Site,” Science, 325, no. 5936 (2009), pp. 58–61.

  “IT MUST BE ICE” Guy Webster, “Bright Chunks at Phoenix Lander’s Mars Site Must Have Been Ice,” NASA (June 19, 2008).

  TEGA AND MECA TEGA was the acronym for Phoenix’s Thermal and Evolved Gas Analyzer, and MECA was the acronym for Phoenix’s Microscopy, Electrochemistry, and Conductivity Analyzer.

  DELIVERING THE SAMPLES PROVED Eric Hand, “Mars Exploration: Phoenix: A Race Against Time,” Nature (Dec. 10, 2008).

  CALCIUM CARBONATE W. V. Boynton, D. W. Ming, S. P. Kounaves, S. M. M. Young, R. E. Arvidson, M. H. Hecht, J. Hoffman, et al., “Evidence for Calcium Carbonate at the Mars Phoenix Landing Site,” Science, 325, no. 5936 (2009), pp. 61–64.

  WATERY PAST Unfortunately, there wasn’t enough water to get an isotopic reading, which would have helped to understand how much water had been lost from the planet.

  WET CHEMISTRY LAB “Microscopy, Electrochemistry, and Conductivity Analyzer (MECA),” Phoenix Mars Mission, University of Arizona.

  SUGAR-CUBE-SIZED The soil samples were one cubic centimeter in volume. See: S. P. Kounaves, “The Phoenix Mars Lander Wet Chemistry Laboratory (WCL): Understanding the Aqueous Geochemistry of the Martian Soil,” International Workshop on Instrumentation for Planetary Missions, vol. 1,683 (2012), p. 1005.

  TINY SENSORS Samuel P. Kounaves, Michael H. Hecht, Steven J. West, John-Michael Morookian, Suzanne M. M. Young, Richard Quinn, Paula Grunthaner, et al., “The MECA Wet Chemistry Laboratory on the 2007 Phoenix Mars Scout Lander,” Journal of Geophysical Research: Planets, 114, no. E3 (2009).

  SLIGHTLY ALKALINE Elizabeth K. Wilson, “Mars Soil PH Measured,” Chemical and Engineering News (June 27, 2008).

  INCLUDING NITRATE Samuel P. Kounaves, et al., “Evidence of Martian Perchlorate, Chlorate, and Nitrate in Mars Meteorite EETA79001: Implications for Oxidants and Organics,” Icarus, 229 (2014), pp. 206–213. We assume nitrogen gas was released into the Martian atmosphere via the exhalations of ancient volcanoes, just as it was here on Earth. Even though life is swimming in nitrogen gas on Earth, the nitrogen isn’t accessible to most organisms: The triple bond is simply too hard to break. Other forms of nitrogen, like nitrate, which hold to oxygen atoms with a bond that can be easily cleaved, are often necessary.

  HYPOTHESIZED TO EXIST Rocco L. Mancinelli and Amos Banin, “Where Is the Nitrogen on Mars?” International Journal of Astrobiology, 2, no. 3 (2003), pp. 217–225.

  DESIGNED TO DETECT NITRATE It would be another few years before nitrate was definitively detected on Mars, by NASA Goddard scientist Jen Stern, using the Sample Analysis at Mars instrument aboard Curiosity. Jennifer C. Stern, Brad Sutter, Caroline Freissinet, Rafael Navarro-González, Christopher P. McKay, P. Douglas Archer, Arnaud Buch, et al., “Evidence for Indigenous Nitrogen in Sedimentary and Aeolian Deposits from the Curiosity Rover Investigations at Gale Crater, Mars,” Proceedings of the National Academy of Sciences, 112, no. 14 (2015), pp. 4,245–4,250.

  SALT CALLED PERCHLORATE Perchlorate is a molecule containing a perchlorate ion (ClO4-, a chlorine atom bonded to four oxygen atoms). The discovery of perchlorate at the Phoenix landing site is detailed here: M. H. Hecht, S. P. Kounaves, R. C. Quinn, S. J. West, S. M. M. Young, D. W. Ming, D. C. Catling, et al., “Detection of Perchlorate and the Soluble Chemistry of Martian Soil at the Phoenix Lander Site,” Science, 325, no. 5936 (2009), pp. 64–67.

  LOOK IT UP Leonard David, “Toxic Mars: Astronauts Must Deal with Perchlorate on the Red Planet,” Space (June 13, 2013).

  JUST A FEW HANDFULS Quoting Mike Hecht, see: Ryan Anderson, “AGU Day 1: Phoenix,” AGU 100 Blogosphere (Dec. 16, 2008).

  CHLORINATED MOLECULES Chloromethane and dichloromethane, e.g. See: Rafael Navarro-González, Edgar Vargas, Jose de La Rosa, Alejandro C. Raga, and Christopher P. McKay, “Reanalysis of the Viking Results Suggests Perchlorate and Organics at Midlatitudes on Mars,” Journal of Geophysical Research: Planets, 115, no. E12 (2010).

  RESIDUES OF CLEANING FLUIDS Guy Webster, “Missing Piece Inspires New Look at Mars Puzzle,” NASA (Sept. 3, 2010).

  WOULD HAVE DESTROYED Kounaves,“The Phoenix Mars Lander Wet Chemistry Laboratory (WCL): Understanding the Aqueous Geochemistry of the Martian Soil,” International Workshop on Instrumentation for Planetary Missions, p. 1005.

  NECESSARILY BAD FOR MICROBES See, for example: John D. Coates and Laurie A. Achenbach, “Microbial Perchlorate Reduction: Rocket-Fueled Metabolism,” Nature Reviews Microbiology, 2, no. 7 (2004), p. 569; Joop M. Houtkooper and Dirk Schulze-Makuch, “The Possible Role of Perchlorates for Martian Life,” Journal of Cosmology, Vol. 5 (Jan. 25, 2010), pp. 930–939; Sophie Nixon, Claire Rachel Cousins, and Charles Cockell, “Plausible Microbial Metabolisms on Mars,” Astronomy & Geophysics (2013).

  THE FREEZING POINT Theoretical eutectic values were determined be 236 ± 1 K for 52 wt% sodium perchlorate and 206 ± 1 K for 44.0 wt% magnesium perchlorate; see: Vincent F. Chevrier, Jennifer Hanley, and Travis S. Altheide, “Stability of Perchlorate Hydrates and Their Liquid Solutions at the Phoenix Landing Site, Mars,” Geophysical Research Letters, 36, no. 10 (2009).

  “A BLACKBOARD HERE” Mars Phoenix, Twitter post (July 8, 2008, 3:15 P.M.).

  “FINISHED HUNKERING DOWN” Ibid. (Oct. 8, 2008, 10:20 P.M.).

  TWEETS TURNED REFLECTIVE Ryan Anderson, “Phoenix Hanging in There,” AGU 100 Blogosphere (Oct. 31, 2008).

  “HEATER TURNING OFF” Mars Phoenix, Twitter post (Oct. 28, 2008, 4:55 P.M.).

  LIKE CIRRUS CLOUDS J. A. Whiteway, et al., “Mars Water-Ice Clouds and Precipitation,” Science, 325, no. 5,936 (2009), pp. 68–70.

  “BARELY WETTING THE SURFACE” Anne Minard, “ ‘Diamond Dust’ Snow Falls Nightly on Mars,” National Geographic News (July 2, 2009).

  “LAZARUS MODE” Eric Hand, “Mars exploration: Phoenix: a race against time,” Nature (Dec. 10, 2008).

  “01010100 01110010 01101001” Mars Phoenix, Twitter post (Nov. 10, 2008, 1:12 P.M.); Rod Pyle, Destination Mars: New Explorations of the Red Planet (Amherst, N.Y.: Prometheus Books, 2012), p. 241.

  A MINI-DVD “Visions of Mars,” The Planetary Society.

  VELCRO’D TO THE DECK Bruce Betts, “We Make It Happen,” The Planetary Report, vol. XXVI, no. 6 (2006), p. 3.

  RUSSIAN MARS MISSION Jon Lomberg, “Visions of Mars: Then and Now,” The Planetary Society.

  “ATTENTION ASTRONAUTS” Ibid.

  BOOKS AND STORIES “Visions of Mars: The Stories,” The Planetary Society.

  SURREALIST PAINTINGS “Visions of Mars: Artwork and Radio Broadcasts,” The Planetary Society.

  THE 1940 RECORDING Ibid.

  IN HIS INTRODUCTION Peter H. Smith, “Introduction to Visions of Mars,” The Planetary Society (Feb. 14, 2007).

  “WOULD NOT BE CURRENT” Ibid.

  HUNDREDS OF YEARS The mini-DVD is expected to last approximately five hundred years. Bruce Betts, “We Make It Happen,” The Planetary Report.

  THE OLDEST PIECES INCLUDED “Visions of Mars: The Stories,” The Planetary Society.

  VOLTAIRE’S “MICROMÉGAS” Voltaire, “Micromégas,” Blake Linton Wilfong, ed., Free Sci-Fi Classics.

  STUDY DROSOPHILA Jeffrey R. Powell, Progress and Prospects in Evolutionary Biology: The Drosophila Model (Oxford University Press, 1997).

  DUTCH BOOK Kees Boeke, Cosmic View: The Universe in 40 Jumps (New York: John Day Company, 1957). This book was also the inspiration for a famous short film, Powers of Ten, produced by Ray and Charles Eames in 1977.

  Chapter 10: Sweet Water

  P
OOLED AND FORMED LAKES “Mars Science Laboratory Landing Site: Gale Crater,” NASA Mars Exploration Program (July 22, 2011).

  INTO THE DEEP NIGHT “NASA Launches Most Capable and Robust Rover to Mars,” NASA Mars Exploration Program (Nov. 26, 2011).

  LANDING VIA A “SKY CRANE” Ravi Prakash, P. Dan Burkhart, Allen Chen, Keith A. Comeaux, Carl S. Guernsey, Devin M. Kipp, Leila V. Lorenzoni, et al., “Mars Science Laboratory Entry, Descent, and Landing System Overview,” IEEE Aerospace Conference (2008), pp. 1–18.

  FEEL A LITTLE CLOSER “Raw Images: Sol 3,” Mars Curiosity Rover Raw Images (Aug, 8, 2012).

  MOUNT SHARP Officially named Aeolis Mons by the International Astronomical Union.

  THICKEST GEOLOGIC RECORDS “Press Kit, Mars Science Laboratory Landing,” NASA (July 2012). Like “the most complete copy of an ancient manuscript,” Mount Sharp can be used to help piece together less complete geologic records from other parts of the planet.

  FILLED WITH SOFT CLAYS R. E. Milliken, J. P. Grotzinger, and B. J. Thomson, “Paleoclimate of Mars as Captured by the Stratigraphic Record in Gale Crater,” Geophysical Research Letters, 37, no. 4 (2010); A. A. Fraeman, et al., “The stratigraphy and Evolution of Lower Mount Sharp from Spectral, Morphological, and Thermophysical Orbital Data Sets,” Journal of Geophysical Research: Planets, 121 (2016), pp. 1,713–1,736.

  “FOLLOW THE WATER” NASA’s goals for Mars have progressed from “Follow the Water” (with several previous missions) to “Explore Habitability” (with NASA’s Curiosity rover) to “Seek Signs of Life” (with NASA’s Mars 2020 mission). See: “The Mars Exploration Program,” NASA Mars Exploration.

  JUST NORTH “Context of Curiosity Landing Site in Gale Crater,” NASA Mars Exploration Program (July 22, 2011).

  FACING EAST-SOUTHEAST Emily Lakdawalla, “Curiosity: Notes from the Two Day-after-Landing Press Briefings,” The Planetary Society (Aug. 6, 2012).

  SETTING THE ROVER DOWN Jason Hanna, “ ‘Impressive’ Curiosity Landing Only 1.5 Miles Off, NASA Says,” CNN (Aug. 14, 2012).

  A FEW KILOMETERS AWAY Curiosity would first need to navigate around the Bagnold Dunes.

  FIRST HUMAN VOICE Charles Bolden, quoted in “First Recorded Voice from Mars,” Mars Science Laboratory, NASA (Aug. 27, 2012).

  TEST ITS COMPONENTS Emily Lakdawalla, “Curiosity Sol 9 Update,” The Planetary Society (Aug. 15, 2012).

  AN ANCIENT RIVERBED R. M. E. Williams, J. P. Grotzinger, W. E. Dietrich, S. Gupta, D. Y. Sumner, R. C. Wiens, N. Mangold, et al., “Martian Fluvial Conglomerates at Gale Crater,” Science, 340, no. 6,136 (2013), pp. 1,068–1,072.

  PERHAPS AS DEEP AS MY HIP Guy Webster, “NASA Rover Finds Old Streambed on Martian Surface,” NASA (September 27, 2012).

  THREE DIFFERENT TYPES J. P. Grotzinger, D. Y. Sumner, L. C. Kah, K. Stack, S. Gupta, L. Edgar, D. Rubin, et al., “A Habitable Fluvio-Lacustrine Environment at Yellowknife Bay, Gale Crater, Mars,” Science, 343, no. 6,169 (2014), p. 1,242,777.

  EXPANSIVE LAKE Ibid.; J. P. Grotzinger, S. Gupta, M. C. Malin, D. M. Rubin, J. Schieber, K. Siebach, D. Y. Sumner, et al., “Deposition, Exhumation, and Paleoclimate of an Ancient Lake Deposit, Gale Crater, Mars,” Science, 350, no. 6,257 (2015), p. aac7575; J. A. Hurowitz, J. P. Grotzinger, W. W. Fischer, S. M. McLennan, R. E. Milliken, N. Stein, A. R. Vasavada, et al., “Redox Stratification of an Ancient Lake in Gale Crater, Mars,” Science, 356, no. 6341 (2017), p. eaah6849; C. Freissinet, D. P. Glavin, Paul R. Mahaffy, K. E. Miller, J. L. Eigenbrode, R. E. Summons, A. E. Brunner, et al., “Organic Molecules in the Sheepbed Mudstone, Gale Crater, Mars,” Journal of Geophysical Research: Planets, 120, no. 3 (2015), pp. 495–514.

  STOOD AS AN ISLAND “A Guide to Gale Crater,” NASA Video (Aug. 2, 2017).

  PAUL MAHAFFY Paul is now the director of the Solar System Exploration Division at NASA Goddard.

  SAMPLE ANALYSIS AT MARS Paul R. Mahaffy, et al., “The Sample Analysis at Mars Investigation and Instrument Suite,” Space Science Reviews, 170, no. 1–4 (2012), pp. 401–478.

  WHEN HE WASN’T STUDYING Salem Solomon, “Born and Raised in Senafe, Eritrea, a NASA Scientist Leads Missions in Space,” Eritrean Press (Aug. 20, 2015).

  GREAT IRON CROSS Ibid.

  LISTENING TO THE WIND Ibid.

  WEIGHING NEARLY AS MUCH SAM comprised 42 percent of the combined instrument weight.

  ANNOUNCED THE DISCOVERY Walter Sullivan, “Two Gases Associated with Life Found on Mars Near Polar Cap,” The New York Times (Aug. 8, 1969).

  A MONTH LATER Johnny Bontemps, “Mystery Methane on Mars: The Saga Continues,” Astrobiology Magazine (May 14, 2015). It turned out that the absorptions over the polar cap could be explained by CO2 ice—see: K. C. Herr and G. C. Pimentel, “Infrared Absorptions Near 3 Microns Recorded over Polar Cap of Mars,” Science, 166 (1969), pp. 496–499.

  CHILE AND HAWAII REPORTED M. J. Mumma, R. E. Novak, M. A. DiSanti, B. P. Bonev, and N. Dello Russo, “Detection and Mapping of Methane and Water on Mars,” Bulletin of the American Astronomical Society, vol. 36 (2004), p. 1,127; Vladimir A. Krasnopolsky, Jean Pierre Maillard, and Tobias C. Owen, “Detection of Methane in the Martian Atmosphere: Evidence for Life?” Icarus, 172, no. 2 (2004), pp. 537–547; Michael J. Mumma, Geronimo L. Villanueva, Robert E. Novak, Tilak Hewagama, Boncho P. Bonev, Michael A. DiSanti, Avi M. Mandell, and Michael D. Smith, “Strong Release of Methane on Mars in Northern Summer 2003,” Science, 323, no. 5,917 (2009), pp. 1,041–1,045.

  ALSO PICKED UP TRACES Vittorio Formisano, Sushil Atreya, Thérèse Encrenaz, Nikolai Ignatiev, and Marco Giuranna, “Detection of Methane in the Atmosphere of Mars,” Science, 306, no. 5,702 (2004), pp. 1,758–1,761.

  A SEASONAL PATTERN Christopher R. Webster, Paul R. Mahaffy, Sushil K. Atreya, Gregory J. Flesch, Michael A. Mischna, Pierre-Yves Meslin, Kenneth A. Farley, et al., “Mars Methane Detection and Variability at Gale Crater,” Science, 347, no. 6,220 (2015), pp. 415–417; Christopher R. Webster, Paul R. Mahaffy, Sushil K. Atreya, John E. Moores, Gregory J. Flesch, Charles Malespin, Christopher P. McKay, et al., “Background Levels of Methane in Mars’ Atmosphere Show Strong Seasonal Variations,” Science, 360, no. 6,393 (2018), pp. 1,093–1,096.

  GEOLOGICAL PROCESS James R. Lyons, Craig Manning, and Francis Nimmo, “Formation of Methane on Mars by Fluid-Rock Interaction in the Crust,” Geophysical Research Letters, 32, no. 13 (2005).

  MATRICES OF MELTING ICE Brendon K. Chastain and Vincent Chevrier, “Methane Clathrate Hydrates as a Potential Source for Martian Atmospheric Methane,” Planetary and Space Science, 55, no. 10 (2007), pp. 1,246–1,256.

  EXHALATIONS OF A SMALL Michael D. Max and Stephen M. Clifford, “The State, Potential Distribution, and Biological Implications of Methane in the Martian Crust,” Journal of Geophysical Research: Planets, 105, no. E2 (2000), pp. 4,165–4,171.

  SAM ALSO CARRIED Paul R. Mahaffy, Christopher R. Webster, Michel Cabane, Pamela G. Conrad, Patrice Coll, Sushil K. Atreya, Robert Arvey, et al., “The Sample Analysis at Mars Investigation and Instrument Suite,” Space Science Reviews, 170, no. 1–4 (2012), pp. 401–478.

  DECIDED TO EXHUME Michael Farquhar, “Remains to Be Seen,” The Washington Post (June 30, 1991).

  STICK AROUND FOR BILLIONS OF YEARS Roger E. Summons, Pierre Albrecht, Gene McDonald, and J. Michael Moldowan, “Molecular Biosignatures,” Strategies of Life Detection (Boston: Springer, 2008), pp. 133–159.

  FOUND NO DEFINITIVE EVIDENCE OF ORGANICS Two key papers on the Viking GC-MS results are: K. Biemann, et al., “Search for Organic and Volatile Inorganic Compounds in Two Surface Samples from the Chryse Planitia Region of Mars,” Science, 194 (1976), pp. 72–76; K. Biemann, et al., “The Search for Organic Substances and Inorganic Volatile Compounds in the Surface of Mars,” J. Geophys. Res., 82 (28) (1977), pp. 4,641–4,658. These results we reinterpreted after the discovery of perchlorate on Mars; see: Rafael Navarro-González, Edg
ar Vargas, Jose de La Rosa, Alejandro C. Raga, and Christopher P. McKay, “Reanalysis of the Viking Results Suggests Perchlorate and Organics at Midlatitudes on Mars,” Journal of Geophysical Research: Planets, 115, no. E12 (2010).

  ONE PART PER BILLION “SAM,” Mars Curiosity Rover, NASA.

  A BABY ASPIRIN Daniel Limonadi, “Sampling Mars, Part 2: Science Instruments SAM and Chemin,” The Planetary Society (Aug. 20, 2012).

  NEUTRAL PH CONDITIONS “View Into ‘John Klein’ Drill Hole in Martian Mudstone,” NASA.

  “ABLE TO DRINK IT” “Quotation of the Day for Wednesday, Mar. 13, 2013,” The New York Times; Carl Franzen, “Curiosity Discovers Ancient Mars Could Have Supported Life,” The Verge (March 12, 2013).

  LONG THIN TUBE Mahaffy et. al., “The Sample Analysis at Mars Investigation and Instrument Suite,” Space Science Reviews; Emily Lakdawalla, The Design and Engineering of Curiosity: How the Mars Rover Performs Its Job (Cham, Switzerland: Springer, 2018).

  SIMPLE COMPOUNDS C. Freissinet, et al., “Organic Molecules in the Sheepbed Mudstone, Gale Crater, Mars,” Journal of Geophysical Research: Planets.

  MORE-COMPLEX MOLECULES, BOUND TOGETHER BY SULFUR J. L. Eigenbrode, R. E. Summons, A. Steele, C. Freissinet, M. Millan, R. Navarro-González, B. Sutter, et al., “Organic Matter Preserved in 3-Billion-Year-Old Mudstones at Gale Crater, Mars,” Science, 360, no. 6,393 (2018), pp. 1,096–1,101; see also: Dwayne Brown and JoAnna Wendel, “NASA Finds Ancient Organic Material, Mysterious Methane on Mars,” NASA (June 7, 2018).

  BUILDING BLOCKS OF LIFE Some of the most exciting results from SAM may be yet to come. The heating method used thus far, pyrolysis, breaks complex organic molecules into simpler components. But nine “wet chemistry” cups have been included as part of SAM’s carousel. Within these cups are solvents that combine with organics. In the presence of these solvents, much less heating is required, lessening the combustion, enabling larger, more complex molecules to waft into SAM’s GC-MS.