chemoautotroph Archives - Astrobiology

Carbon-silicate cycle includes a carbon dioxide (CO2) dissolution in rainwater to form carbonic acid (H2CO3) that falls on land and oceans; b reaction of H2CO3 and silicate (SiO32-) to form silicon dioxide (SiO2) and carbonate (CO32-), which is sequestered into oceanic crust for further recycling to the mantle followed by release into the atmosphere through volcanic activity; and c regeneration of CO2 through reaction between SiO2 and CO32-. Carbon fixation includes (d) reduction of CO2 to methane (CH4) through (e) the production of H2 from H2O on the surface of iron sulfide minerals that serve as sources of dissolved ferrous ion (Fe2+), which is photochemically oxidized to ferric ions (Fe3+.) in water vapor. Carbon monoxide (CO) either reacts with (f) H2O for synthesis of formic acid (HCOOH) or g ammonia (NH3) for synthesis of formamide (HCONH2). Hydrogen cyanide (HCN) formation may occur through either h reaction between CH4 and NH3 or i reaction of CH3• and N• through free radical mechanism. j HCN further reacts with H2O to produce CO and NH3.that also is produced through (k) N2 fixation under high temperatures, both can be sequestered into the mantle; l NH3 photolysis by UV radiation gives rise to N2 and H2; m hydrothermal H2 production occurs through the H2O oxidation by Fe2+ into H2 used for N2 fixation in the atmosphere. In this figure, royalty-free mountain and meteorite images designed by Freepik platform (www.freepik.com) are used. -- Nature via PubMed (open access)

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Habitable Zones, Origin & Evolution of Life, Status Report

Redox Chemistry Of Early Earth And The Origin Of Life

by Keith CowingApril 4, 2026April 4, 2026

Multiple controversial scenarios have been proposed explaining the emergence of life, both from environmental and chemical perspectives.

Photo courtesy of Andrew Wozniak, University of Delaware; HOV Alvin Team; Funder: NSF. © Woods Hole Oceanographic Institution

Away Teams & Field Reports, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Caves, Craters, Mountains, Subsurface, Lava Tubes, Exploration Gear & Tech, Extremeophiles and Extreme Environments, Habitable Zones, Imaging & Spectroscopy, Lava / magma ocean / Volcanic Worlds, Mapping, Geodesy, Cartography, Bathymetry, Press Release, Robotics/Rovers/UAVs, ROVs/Submersibles/Diving, Sample Return, Tricorders & Sensors, Water/Hycean Worlds & Oceanography

Ocean Planet Exploration: Alvin Crew Witnesses Seafloor Eruption On The East Pacific Rise

by Keith CowingMay 14, 2025May 14, 2025

Scientists diving in the human-occupied vehicle Alvin recently witnessed a rare but predicted seafloor eruption along the mid-ocean ridge axis at 9°50’N on the East Pacific Rise.

Eruption of Old Faithful geyser

Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Extremeophiles and Extreme Environments, Habitable Zones, Microbiology & Virology, Press Release

Extreme Habitats: Microbial Life In Old Faithful Geyser

by Keith CowingOctober 12, 2023October 12, 2023

An eruption of Old Faithful Geyser in Yellowstone National Park is a sight to behold. Indeed, millions of tourists flock to the park each year to see it. Hot water […]