Title
Enhanced Resolution of Chiral Amino Acids with Capillary Electrophoresis for Biosignature Detection in Extraterrestrial Samples
Authors
Jessica S. Creamer, Maria F. Mora, Peter A. Willis
Abstract
Amino acids are fundamental building blocks of terrestrial life as well as ubiquitous byproducts of abiotic reactions. In order to distinguish between amino acids formed by abiotic versus biotic processes it is possible to use chemical distributions to identify patterns unique to life. This article describes two capillary electrophoresis methods capable of resolving 17 amino acids found in high abundance in both biotic and abiotic samples (seven enantiomer pairs d/l-Ala, -Asp, -Glu, -His, -Leu, -Ser, -Val and the three achiral amino acids Gly, β-Ala, and GABA). To resolve the 13 neutral amino acids one method utilizes a background electrolyte containing γ-cyclodextrin and sodium taurocholate micelles. The acidic amino acid enantiomers were resolved with γ-cyclodextrin alone. These methods allow detection limits down to 5 nM for the neutral amino acids and 500 nM for acidic amino acids and were used to analyze samples collected from Mono Lake with minimal sample preparation.
Title
The Sample Analysis at Mars Investigation and Instrument Suite
Authors
Paul R. Mahaffy, Christopher R. Webster, Michel Cabane, Pamela G. Conrad, Patrice Coll, Sushil K. Atreya, Robert Arvey, Michael Barciniak, Mehdi Benna, Lora Bleacher, William B. Brinckerhoff, Jennifer L. Eigenbrode, Daniel Carignan, Mark Cascia, Robert A. Chalmers, Jason P. Dworkin, Therese Errigo, Paula Everson, Heather Franz, Rodger Farley, Steven Feng, Gregory Frazier, Caroline Freissinet, Daniel P. Glavin, Daniel N. Harpold, Douglas Hawk, Vincent Holmes, Christopher S. Johnson, Andrea Jones, Patrick Jordan, James Kellogg, Jesse Lewis, Eric Lyness, Charles A. Malespin, David K. Martin, John Maurer, Amy C. McAdam, Douglas McLennan, Thomas J. Nolan, Marvin Noriega, Alexander A. Pavlov, Benito Prats, Eric Raaen, Oren Sheinman, David Sheppard, James Smith, Jennifer C. Stern, Florence Tan, Melissa Trainer, Douglas W. Ming, Richard V. Morris, John Jones, Cindy Gundersen, Andrew Steele, James Wray, Oliver Botta, Laurie A. Leshin, Tobias Owen, Steve Battel, Bruce M. Jakosky, Heidi Manning, Steven Squyres, Rafael Navarro-González, Christopher P. McKay, Francois Raulin, Robert Sternberg, Arnaud Buch, Paul Sorensen, Robert Kline-Schoder, David Coscia, Cyril Szopa, Samuel Teinturier, Curt Baffes, Jason Feldman, Greg Flesch, Siamak Forouhar, Ray Garcia, Didier Keymeulen, Steve Woodward, Bruce P. Block, Ken Arnett, Ryan Miller, Charles Edmonson, Stephen Gorevan, Erik Mumm
Abstract
The Sample Analysis at Mars (SAM) investigation of the Mars Science Laboratory (MSL) addresses the chemical and isotopic composition of the atmosphere and volatiles extracted from solid samples. The SAM investigation is designed to contribute substantially to the mission goal of quantitatively assessing the habitability of Mars as an essential step in the search for past or present life on Mars. SAM is a 40 kg instrument suite located in the interior of MSL’s Curiosity rover. The SAM instruments are a quadrupole mass spectrometer, a tunable laser spectrometer, and a 6-column gas chromatograph all coupled through solid and gas processing systems to provide complementary information on the same samples. The SAM suite is able to measure a suite of light isotopes and to analyze volatiles directly from the atmosphere or thermally released from solid samples. In addition to measurements of simple inorganic compounds and noble gases SAM will conduct a sensitive search for organic compounds with [read more]The Sample Analysis at Mars (SAM) investigation of the Mars Science Laboratory (MSL) addresses the chemical and isotopic composition of the atmosphere and volatiles extracted from solid samples. The SAM investigation is designed to contribute substantially to the mission goal of quantitatively assessing the habitability of Mars as an essential step in the search for past or present life on Mars. SAM is a 40 kg instrument suite located in the interior of MSL’s Curiosity rover. The SAM instruments are a quadrupole mass spectrometer, a tunable laser spectrometer, and a 6-column gas chromatograph all coupled through solid and gas processing systems to provide complementary information on the same samples. The SAM suite is able to measure a suite of light isotopes and to analyze volatiles directly from the atmosphere or thermally released from solid samples. In addition to measurements of simple inorganic compounds and noble gases SAM will conduct a sensitive search for organic compounds with either thermal or chemical extraction from sieved samples delivered by the sample processing system on the Curiosity rover’s robotic arm.
Title
Characterization and Calibration of the CheMin Mineralogical Instrument on Mars Science Laboratory
Authors
David Blake, David Vaniman, Cherie Achilles, Robert Anderson, David Bish, Tom Bristow, Curtis Chen, Steve Chipera, Joy Crisp, David Des Marais, Robert T. Downs, Jack Farmer, Sabrina Feldman, Mark Fonda, Marc Gailhanou, Hongwei Ma, Doug W. Ming, Richard V. Morris, Philippe Sarrazin, Ed Stolper, Allan Treiman, Albert Yen
Abstract
A principal goal of the Mars Science Laboratory (MSL) rover Curiosity is to identify and characterize past habitable environments on Mars. Determination of the mineralogical and chemical composition of Martian rocks and soils constrains their formation and alteration pathways, providing information on climate and habitability through time. The CheMin X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument on MSL will return accurate mineralogical identifications and quantitative phase abundances for scooped soil samples and drilled rock powders collected at Gale Crater during Curiosity’s 1-Mars-year nominal mission. The instrument has a Co X-ray source and a cooled charge-coupled device (CCD) detector arranged in transmission geometry with the sample. CheMin’s angular range of 5∘ to 50∘ 2θ with <0.35∘ 2θ resolution is sufficient to identify and quantify virtually all minerals. CheMin’s XRF requirement was descoped for technical and budgetary reasons. However, X-ray [read more]A principal goal of the Mars Science Laboratory (MSL) rover Curiosity is to identify and characterize past habitable environments on Mars. Determination of the mineralogical and chemical composition of Martian rocks and soils constrains their formation and alteration pathways, providing information on climate and habitability through time. The CheMin X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument on MSL will return accurate mineralogical identifications and quantitative phase abundances for scooped soil samples and drilled rock powders collected at Gale Crater during Curiosity’s 1-Mars-year nominal mission. The instrument has a Co X-ray source and a cooled charge-coupled device (CCD) detector arranged in transmission geometry with the sample. CheMin’s angular range of 5∘ to 50∘ 2θ with <0.35∘ 2θ resolution is sufficient to identify and quantify virtually all minerals. CheMin’s XRF requirement was descoped for technical and budgetary reasons. However, X-ray energy discrimination is still required to separate Co Kα from Co Kβ and Fe Kα photons. The X-ray energy-dispersive histograms (EDH) returned along with XRD for instrument evaluation should be useful in identifying elements Z>13 that are contained in the sample. The CheMin XRD is equipped with internal chemical and mineralogical standards and 27 reusable sample cells with either Mylar® or Kapton® windows to accommodate acidic-to-basic environmental conditions. The CheMin flight model (FM) instrument will be calibrated utilizing analyses of common samples against a demonstration-model (DM) instrument and CheMin-like laboratory instruments. The samples include phyllosilicate and sulfate minerals that are expected at Gale crater on the basis of remote sensing observations.