Challenges in the Search for Perchlorate and Other Hydrated Minerals With 2.1‐μm Absorptions on Mars
Year: 2018
Type: article
Abstract: A previously unidentified artifact has been found in Compact Reconnaissance Imaging Spectrometer for Mars targeted I/F data. It exists in a small fraction (<0.05%) of pixels within 90% of images investigated and occurs in regions of high spectral/spatial variance. This artifact mimics real mineral absorptions in width and depth and occurs most often at 1.9 and 2.1 μm, thus interfering in the search for some mineral phases, including alunite, kieserite, serpentine, and perchlorate. A filtering step in the data processing pipeline, between radiance and I/F versions of the data, convolves narrow artifacts ("spikes") with real atmospheric absorptions in these wavelength regions to create spurious absorption-like features. The majority of previous orbital detections of alunite, kieserite, and serpentine we investigated can be confirmed using radiance and raw data, but few to none of the perchlorate detections reported in published literature remain robust over the 1.0- to 2.65-μm wavelength range. PLAIN LANGUAGE SUMMARY: Many minerals can be identified with remote sensing data by their characteristic absorptions in visible-shortwave infrared data. This type of data has allowed geological interpretation of much of Mars' surface, using satellite-based observation. We have discovered an issue with the Compact Reconnaissance Imaging Spectrometer for Mars instrument's data processing pipeline. In ~ <0.05% of pixels in almost all images, noise in the data is smoothed in such a way that it mimics real mineral absorptions, falsely making it look as though certain minerals are present on Mars' surface. The vast majority of previously identified minerals are still confirmed after accounting for the artifact, but some to all perchlorate detections and a few serpentine detections were not confirmed, suggesting that the artifact created false detections. This means concentrated regions of perchlorate may not occur on Mars and so may not be available to generate possibly habitable salty liquid water at very cold temperatures.
Source: Geophysical Research Letters
DOI: 10.1029/2018gl080077
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,190
Awards: CAREER: Self-adjusting Models as a New Direction in Machine Learning, G6671297155, THE OVERARCHING GOAL OF THIS PROPOSAL IS TO ENHANCE UNDERSTANDING OF HOW THE SURFACE AND SUBSURFACE OF MARS MAY BE IN COMMUNICATION TO BRING WATERS OF DISTINCTIVE GEOCHEMISTRIES TO THE SURFACE. GLOBAL MINERAL MAPPING BY CRISM AT HIGH RESOLUTION SHOWS THAT THE SPATIAL DISTRIBUTION OF SULFATE CHLORIDE AND CARBONATE SALTS IS HIGHLY VARIABLE. REACTIVE TRANSPORT MODELING USING PLAUSIBLE MINERAL ASSEMBLAGES IN AND AROUND THE NILI FOSSAE REGION HAS SHOWN THAT ITS CARBONATE MAY RESULT FROM REACTION OF ATMOSPHERICALLY-DERIVED GROUNDWATERS WITH THE UPPER TENS OF METERS OF HIGH-OLIVINE BEARING BASALT TO PRODUCE CARBONATE. HOWEVER WHAT IS THE SOURCE INSTEAD FOR CHLORIDE AND SULFATE DEPOSITS INCLUDING THE ACID SULFATES? A SUBSURFACE SOURCE OF ANIONS MAY BE REQUIRED. HERE WE PROPOSE A MAPPING INVESTIGATION OF THE TERRA SIRENUM REGION ON MARS SITE OF PALEOLAKE DEPOSITS HOSTING ALUNITE AND JAROSITE AND BASINS HOSTING CHLORIDES. RECENTLY LARGE SCALE FAULTS IN THE REGION HAVE ALSO BEEN MAPPED. THESE SUGGEST A MEANS FOR WATERS CIRCULATING AT DEPTH TO REACH THE SUBSURFACE. WE WILL TEST THE HYPOTHESIS THAT THE PRESENCE AND SOURCE OF UPWELLING SUBSURFACE WATERS I.E. THE PLUMBING OF MARTIAN SHALLOW OR DEEP LAKES PLAYS A CRUCIAL ROLE IN THE DEVELOPMENT OF MARTIAN PALEOLAKES WITH DISTINCTIVE GEOCHEMISTRIES AND THUS DISTINCTIVE MINERAL ASSEMBLAGES AND BIOLOGICAL POTENTIAL. OUR OBJECTIVES ARE (I) TO MAP THE DISTRIBUTIONS OF SECONDARY (WATER-RELATED) MINERALS IN THE TERRA SIRENUM REGION IN RELATION TO GEOLOGICAL FEATURES AND (II) TO CONSTRAIN THE SOURCES AND QUANTITIES OF S AND CL THAT FORM OBSERVED SALT-RICH DEPOSITS AND THUS CONTROL THE HABITABILITY AND BIOLOGICAL POTENTIAL OF WATERS. IN PARTICULAR USING OBSERVED MINERALOGY AND OBSERVED SPATIAL RELATIONSHIPS BETWEEN GEOLOGIC UNITS WE WILL EXAMINE THE PLAUSIBILITY OF (1) ATMOSPHERICALLY-SOURCED VOLATILES INTERACTING WITH SURFACE ROCKS AND SOILS TO PROVIDE S AND CL (2) WEATHERING OF SULFIDES FROM IGNEOUS ROCK (3) REMOBILIZATION OF PRIOR GENERATIONS OF BURIED SALT DEPOSITS OR (4) INTERACTION WITH MAGMATIC GASES.
OpenAlex ID: W2900084613