title: Subcritical water extractor for Mars analog soil analysis.
abstract: Abstract Technologies that enable rapid and efficient extraction of biomarker compounds from various solid matrices are a critical requirement for the successful implementation of in situ chemical analysis of the martian regolith. Here, we describe a portable subcritical water extractor that mimics multiple organic solvent polarities by tuning the dielectric constant of liquid water through adjustment of temperature and pressure. Soil samples, collected from the Yungay region of the Atacama Desert (martian regolith analogue) in the summer of 2005, were used to test the instrument's performance. The total organic carbon was extracted from the samples at concentrations of 0.2-55.4 parts per million. The extraction data were compared to the total organic carbon content in the bulk soil, which was determined via a standard analytical procedure. The instrument's performance was examined over the temperature range of 25-250 degrees C at a fixed pressure of 20.7 MPa. Under these conditions, water remains in a subcritical fluid state with a dielectric constant varying between approximately 80 (at 25 degrees C) and approximately 30 (at 250 degrees C).
authors.affiliation: Jet Propulsion Laboratory and California Institute of Technology, Pasadena, California, USA. Xenia.Amashukeli@jpl.nasa.gov
authors.forename: Xenia
authors.initials: X
authors.lastname: Amashukeli
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Grunthaner
authors.forename: Steven B
authors.initials: SB
authors.lastname: Patrick
authors.forename: Pun To
authors.initials: PT
authors.lastname: Yung
mesh_terms: D003889:Desert Climate; D005118:Extraterrestrial Environment / Q000737:chemistry*; D018535:Mars; D011312:Pressure; D012987:Soil / Q000032:analysis*; D013026:Space Flight / Q000295:instrumentation*; D013696:Temperature; D014867:Water / Q000032:analysis*
chemical_list: D012987:Soil; D014867:Water