Lipid molecules are organic compounds, insoluble in water, and based on carbon-carbon chains that form an integral part of biological cell membranes. As such, lipids are ubiquitous in life on Earth, which is why they are considered useful biomarkers for life detection in terrestrial environments. These molecules display effective membrane-forming properties even under geochemically hostile conditions that challenge most of microbial life, which grants lipids a universal biomarker character suitable for life detection beyond Earth, where a putative biological membrane would also be required. What discriminates lipids from nucleic acids or proteins is their capacity to retain diagnostic information about their biological source in their recalcitrant hydrocarbon skeletons for thousands of millions of years, which is indispensable in the field of astrobiology given the time span that the geological ages of planetary bodies encompass. This work gathers studies that have employed lipid biomarker approaches for paleoenvironmental surveys and life detection purposes in terrestrial environments with extreme conditions: hydrothermal, hyperarid, hypersaline, and highly acidic, among others; all of which are analogous to current or past conditions on Mars. Although some of the compounds discussed in this review may be abiotically synthesized, we focus on those with a biological origin, namely lipid biomarkers. Therefore, along with appropriate complementary techniques such as bulk and compound-specific stable carbon isotope analysis, this work recapitulates and reevaluates the potential of lipid biomarkers as an additional, powerful tool to interrogate whether there is life on Mars, or if there ever was.

An Overview of Lipid Biomarkers in Terrestrial Extreme Environments with Relevance for Mars Exploration

Chlorine has important roles in the Earth's systems. In different forms, it helps balance the charge and osmotic potential of cells, provides energy for microorganisms, mobilizes metals in geologic fluids, alters the salinity of waters, and degrades atmospheric ozone. Despite this importance, there has not been a comprehensive summary of chlorine's geobiology. Here, we unite different areas of recent research to describe a biogeochemical cycle for chlorine. Chlorine enters the biosphere through volcanism and weathering of rocks and is sequestered by subduction and the formation of evaporite sediments from inland seas. In the biosphere, chlorine is converted between solid, dissolved, and gaseous states and in oxidation states ranging from −1 to +7, with the soluble, reduced chloride ion as its most common form. Living organisms and chemical reactions change chlorine's form through oxidation and reduction and the addition and removal of chlorine from organic molecules. Chlorine can be transported through the atmosphere, and the highest oxidation states of chlorine are produced by reactions between sunlight and trace chlorine gases. Partial oxidation of chlorine occurs across the biosphere and creates reactive chlorine species that contribute to the oxidative stress experienced by living cells. A unified view of this chlorine cycle demonstrates connections between chlorine biology, chemistry, and geology that affect life on the Earth.

The biogeochemical cycling of chlorine

Sulfate-rich sedimentary rocks explored by the Opportunity rover during its 14-year surface mission at Meridiani Planum provide an invaluable window into the thousands of sulfate deposits detected on Mars via remote sensing. Existing models explaining the formation of martian sulfates can be generally described as either bottom-up, groundwater-driven playa settings or top-down icy chemical weathering environments. Here, we propose a hybrid model involving both bottom-up and top-down processes driven by freeze-thaw cycles. Freezing leads to cryo-concentration of acidic fluids from precipitations at the surface, facilitating rapid chemical weathering despite low temperatures. Cryosuction causes the upward migration of vadose water and even groundwater with dissolved ions, resulting in the accumulation of ions in near-surface environments. Evaporation precipitates salts, but leaching separates chlorides from sulfates during the thawing period. Freeze-thaw cycles, therefore, can enrich sulfates at the surface. While freeze-thaw is more commonly understood as a mechanism of physical weathering, we suggest that it is a fundamental aspect of chemical weathering on Mars.

Freeze-thaw cycles drove chemical weathering and enriched sulfates in the Burns formation at Meridiani, Mars

Stable oxychlorides, mainly composed of ClO4–, ClO3–, or their mixture, are significantly enriched on the Martian surface (up to ∼0.5%) compared to Earth. ClO4– and ClO3– have different physicochemical properties and biological activities. They are also important candidates for in situ resource utilization (ISRU) and even the food sources of potential Martian lives. Therefore, it is of great scientific significance to determine the species of oxychlorides, especially the ratio of ClO4–/ClO3– on the Martian surface, not only for Martian environmental evolution and life search but also for Martian resource development. In this study, first, a simulation of oxychloride generation by electrostatic discharge (ESD) of the Martian dust storm was performed under simulated Martian conditions. Second, the spectral features of the Fourier transform infrared attenuated total reflection (FTIR-ATR) spectra and liquid transmission (FTIR-TR) spectra of ClO4– and ClO3– were characterized, and a quantitative model between their IR spectra and their concentrations was built. Finally, the concentration of ClO4– and ClO3– in the ESD reaction product under various reaction times and the ratio of ClO4–/ClO3– was detected and analyzed. Our results provide valuable information for the study of the origin of the mechanism, the scientific estimation of the abundance and the species of oxychlorides on the Martian surface, and even the feasibility of ISRU on the Martian surface. 

Oxychloride Generation by Electrostatic Discharge (ESD) of Martian Dust and Detection by Infrared Spectroscopy

Perchlorates on mars: Occurrence and implications for putative life on the red planet

Preferential Formation of Chlorate over Perchlorate on Mars Controlled by Iron Mineralogy

Understanding crust–atmosphere interactions on Venus is fundamentally important to interpretations of Venus’ surface spectroscopic data. Olivine, in basaltic crust, is oxidized under a heated CO2 atmosphere. However, the oxidation rates, product assemblages and spectral characteristics of olivine samples with different Fa# values remain largely unclear. Herein, we investigated the oxidation of olivine with different Fa# values (Fa09, Fa29 and Fa71) under CO2 atmosphere at 470 °C and 900 °C and characterized the oxidation products (both microscopically and macroscopically), conversion rates and VNIR spectra. The results showed that the oxidation of olivine produced magnesioferrite, magnetite, laihunite, hematite and maghemite at 470 °C and hematite, magnetite, magnesioferrite and amorphous SiO2 at 900 °C. Both high temperature and high Fa# values accelerated the oxidation rates. The production of oxide coatings on olivine grains (74 μm in size) was estimated to be completed within tens to hundreds of years at 470 °C in natural settings, with even shorter periods under higher temperatures. Thus, CO2 oxidation would quickly eliminate olivine spectral characteristics, and spectral parameters at 850 and 1020 nm, as well as other relevant spectral windows (considering shifts induced by the elevated temperature), could be used to trace olivine oxidation processes. This work presented a case study connecting microscopic features to spectral characteristics for Venus’ surface–atmosphere interactions. Further studies considering more realistic Venus’ surface–atmosphere conditions will be essential to better interpret the measured spectroscopic data and determine the origins of the high emissivity detected on elevated terrain on Venus.

/pdf/high-temperature-oxidation-of-magnesium-and-iron-rich-10lycdzy.pdf

High-Temperature Oxidation of Magnesium- and Iron-Rich Olivine under a CO2 Atmosphere: Implications for Venus

ATMOSPHERE. Di-Sheng Zhou, Yu-Yan Sara Zhao*, Chao Qi, Hua-Pei Wang, Jun-Xiang Miao, HongLei Lin, Jun-Hu Wang, Yan-Xue Wu, Shi-Ling Yang, Xiong-Yao Li, Jian-Zhong Liu. Center for Lunar and Planetary Sciences, Institute of Geochemistry, CAS, Guiyang, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China; CAS Center for Excellence in Comparative Planetology, Hefei, China; Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, CAS, Beijing, China; Paleomagnetism and Planetary Magnetism Laboratory, School of Geophysics and Geomatics, China University of Geosciences, Wuhan, China; Center for Advanced Mössbauer Spectroscopy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China; Analysis and Test Center, Guangdong University of Technology, Guangzhou, China; Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, CAS, Beijing, China. (*Email: zhaoyuyan@mail.gyig.ac.cn)

Experimental constraints on iron-rich olivine weathering under mars atmosphere.

Fe behavior on the surface of early Mars: Insights from weathering Fe-rich olivine

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Jun-Hu Wang

Author Tools

Chat about Author

Papers

Preferential Formation of Chlorate over Perchlorate on Mars Controlled by Iron Mineralogy

High-Temperature Oxidation of Magnesium- and Iron-Rich Olivine under a CO2 Atmosphere: Implications for Venus

Experimental constraints on iron-rich olivine weathering under mars atmosphere.

Fe behavior on the surface of early Mars: Insights from weathering Fe-rich olivine