ABSTRACT
The Phoenix mission investigated patterned ground and weather in the northern arctic region of Mars for 5 months starting 25 May 2008 (solar longitude between 76.5 degrees and 148 degrees ). A shallow ice table was uncovered by the robotic arm in the center and edge of a nearby polygon at depths of 5 to 18 centimeters. In late summer, snowfall and frost blanketed the surface at night; H(2)O ice and vapor constantly interacted with the soil. The soil was alkaline (pH = 7.7) and contained CaCO(3), aqueous minerals, and salts up to several weight percent in the indurated surface soil. Their formation likely required the presence of water.
Subject(s)
Ice , Mars , Water , Calcium Carbonate , Extraterrestrial Environment , Hydrogen-Ion Concentration , Robotics , Spacecraft , TemperatureABSTRACT
The Wet Chemistry Laboratory on the Phoenix Mars Lander performed aqueous chemical analyses of martian soil from the polygon-patterned northern plains of the Vastitas Borealis. The solutions contained approximately 10 mM of dissolved salts with 0.4 to 0.6% perchlorate (ClO4) by mass leached from each sample. The remaining anions included small concentrations of chloride, bicarbonate, and possibly sulfate. Cations were dominated by Mg2+ and Na+, with small contributions from K+ and Ca2+. A moderately alkaline pH of 7.7 +/- 0.5 was measured, consistent with a carbonate-buffered solution. Samples analyzed from the surface and the excavated boundary of the approximately 5-centimeter-deep ice table showed no significant difference in soluble chemistry.
Subject(s)
Anions , Cations , Mars , Perchlorates , Chemical Phenomena , Extraterrestrial Environment , Hydrogen-Ion Concentration , Oxidation-Reduction , Solubility , Spacecraft , Temperature , WaterABSTRACT
Carbonates are generally products of aqueous processes and may hold important clues about the history of liquid water on the surface of Mars. Calcium carbonate (approximately 3 to 5 weight percent) has been identified in the soils around the Phoenix landing site by scanning calorimetry showing an endothermic transition beginning around 725 degrees C accompanied by evolution of carbon dioxide and by the ability of the soil to buffer pH against acid addition. Based on empirical kinetics, the amount of calcium carbonate is most consistent with formation in the past by the interaction of atmospheric carbon dioxide with liquid water films on particle surfaces.
Subject(s)
Calcium Carbonate , Mars , Carbon Dioxide , Chemical Precipitation , Extraterrestrial Environment , Hot Temperature , Hydrogen-Ion Concentration , Spacecraft , WaterABSTRACT
NASA: Researchers describe research design and equipment for electrochemical analysis of Martian soil. The Wet Chemistry Laboratory (WCL) was designed for the Mars Surveyor 2001 Lander by the Mars Environmental Compatibility Assessment (MECA) team. The WCL consists of four beakers, each containing an integral array of electrochemical sensors. In addition to describing WCL design, the article discusses WCL sensor selection and design, analytical goals of the MECA experiments, expected composition of the Martian regolith, survival and performance testing, and reference electrode selection. The description of the research design describes experiment initiation, warm-up, leaching solution, calibration, sampling, analysis, reagent addition, and data analysis.^ieng
