biotic biosignature Archives

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Status Report

Open-Ended Versus Bounded Evolution: Mineral Evolution As A Case Study

by Keith CowingJune 26, 2024June 26, 2024

To what extent are natural evolving systems limited in their potential diversity (i.e., “bounded”) versus unrestricted (“open-ended”)? Minerals provide a quantitative model evolving system, with well documented increases in mineral […]

(A) Schematic of assumptions concerning the outer layers of Enceladus, where H2 (and other solutes) and H2O erupt from the subsurface ocean as a plume of gas. As solutes and H2O vaporize and travel through the tiger stripes, H2O condenses onto the surrounding ice shell as it travels outward, enriching the plume in solutes. Once out of the ice shell conduit, the ratio of solutes to H2O remains the same as the gases expand into the vacuum of space and are detected by Cassini’s INMS. (B) Calculated log aqueous activities (at 273.15 K) of constrained species, resulting from the process illustrated in the left panel using data from Table 1, are displayed as functions of tiger-stripe temperatures. The dashed curve represents a hypothetical organic molecule detected at 1 ppm in the plume gas and then converted into log aqueous activity. -- chemrxiv.org

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, SETI & Technosignatures, Status Report, Tricorders & Sensors, Water/Hycean Worlds & Oceanography

Distinguishing Potential Organic Biosignatures on Ocean Worlds from Abiotic Geochemical Products using Thermodynamic Calculations

by Keith CowingMay 9, 2024May 9, 2024

The search for life in our solar system often involves efforts to detect organic molecules, which have been found on many extraterrestrial bodies, including planets, moons, meteorites, comets, and asteroids. […]