October 2024 – My WordPress Site

Physicist Stephen Hawking in Zero Gravity -- Wikipedia Larger image

Astrobiology (general), Intelligence & Language, Interstellar, People Of Astrobiology, SETI & Technosignatures, Societal Issues

Stephen Hawking’s Warning on Contacting Aliens: A Physics Perspective on the Intelligence Trap

by Keith CowingOctober 31, 2024October 31, 2024

The search for extraterrestrial intelligence is a fascinating and important endeavor, but it raises significant ethical and safety concerns. In the search for extraterrestrial intelligence, scientists use knowledge of physics to identify potential communication methods and signals that may be used by extraterrestrial civilizations.

Europa Clipper making a flyby of Europa -- NASA

Europa, Ganymede, Icy Worlds, Jupiter, Microbiology & Virology, Missions & Hardware, Planetary Protection & Biosafety, Radiation, Water/Hycean Worlds & Oceanography

Europa Clipper Planetary Protection Probabilistic Risk Assessment Summary

by Keith CowingOctober 31, 2024October 31, 2024

Panel A: Schematic representation for the formation of the Fe vacanciess on the (011)FeS surface. Panel B: optimized geometries for the original, non-defective, slab, the slab with a single Fe vacancy and the slab with two Fe vacancies (S atoms are in yellow and Fe atoms in orange). Fe atoms highlighted in blue colour are the ones removed on the process. S atoms highlighted in red are the most reactive ones in each structure. -- astro-ph.SR)

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Meteorites & Asteroids

Reactivity Of Chondritic Meteorites Under H2-rich Atmospheres: Formation Of H2S

by Keith CowingOctober 31, 2024October 31, 2024

Comparative plot for the discovery spaces of Gaia and Theia, emphasizing Theia higher precision which enables the exploration of a new discovery space (data extracted from the 22-Oct-2024 version of the Encyclopaedia of exoplanetary systems catalog). -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Stellar Cartography

High Precision Astrometry Science In The Context of Space Mission Prospectives

by Keith CowingOctober 31, 2024October 31, 2024

a, Mantle melting is predicted to last 5 Myr or more. b, A rheological transition in the crust on timescales of ~105 years throttles ascent of magmas from deeper storage regions. c, SCION sensitivity tests for the end-Permian with median Siberian Traps co-eruptive outgassing and cryptic degassing ranging from 1013 to 3 × 1013 mol CO2 yr−1 for 2, 4, 6 or 8 Myr, showing that maintaining a given level of warming requires a minimum CO2 flux; if cryptic degassing satisfies this flux, the duration of warming depends on the duration of cryptic degassing and cumulative emissions. d, The combined influence of prolonged mantle melting and declining surface volcanism decouples CO2 flux from volcanic output, with high cryptic CO2 fluxes during early and waning phases of LIP emplacement. During early emplacement, magmas solidify in the cold lithosphere, exsolving gas. During late emplacement, the rheologic shift shown in b inhibits eruptions, but cryptic degassing continues from magmas solidifying in the lower crust and mantle lithosphere.

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Extinction events, Lava / magma ocean / Volcanic Worlds, Terraforming & Geoengineering

Carbon Dioxide Release From Magma Deep Beneath Ancient Volcanoes Was A Hidden Driver Of Earth’s Past Climate

by Keith CowingOctober 31, 2024October 31, 2024

Time evolution (from left to right) of small grains around Makemake under the influence of solar radiation pressure. -- astro-ph.EP

Astrochemistry, Astrogeology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy

Prominent Mid-infrared Excess Of The Dwarf Planet (136472) Makemake Discovered by JWST/MIRI Indicates Ongoing Activity

by Keith CowingOctober 31, 2024October 31, 2024

The Carboxysulfitic Scenario. A conceptual diagram linking the carboxysulfitic reaction network and a geochemical environment. Volcanic outgassing supplies SO2 and CO2 to the atmosphere which can then dissolve in mildly alkaline lakes. Dissolution leads to the formation of bicarbonate (HCO3-) and sulfite (SO32-). Photochemical reactions involving UV photons and SO32- can lead to the production of solvated electrons. These solvated electrons can then be used to reduce CO2 . The effective rate constant for this multi-step reaction is denoted as keff. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Caves, Craters, Mountains & Lava Tubes, Habitable Zones, Mars, Sample Return

Shedding A Light On The Kinetics Of The Carboxysulfitic Scenario

by Keith CowingOctober 31, 2024October 31, 2024

Comparison of 2D distribution of A(V), R(V), qPAH for dust clouds. For A(V) and R(V) maps, we select high-quality stars from Zhang & Green (2024), and remove lines of sight where only partial extinction is covered by XP. For qPAH map, we remove lines of sight where the qPAH map is of low quality (χ 2 /DOF > 3 or qPAH/σ(qPAH) < 3), or that cross multiple clouds (Equation 1). The binning method and selection of stars in the 2D maps are described in Appendix A. Despite different baselines and finer structures in different maps, all clouds tend to have lower R(V ) at high-qPAH regions, as indicated quantitatively on the per-star basis in Figure 5 -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Imaging & Spectroscopy, Interstellar, Mapping, Geodesy, Cartography, Stellar Cartography

Dust Extinction-curve Variation In The Translucent Interstellar Medium Is Driven By PAH Growth

by Keith CowingOctober 31, 2024October 31, 2024

Sky positions of exoplanet-hosting stars projected on Molleweide map. HZS are denoted by yellow-green circles, while the remaining population of exoplanets is represented by gray circles. The studied sample of 84 HZS, located within 220 pc of the Sun, is represented by crossed yellow-green circles. The three high-density HZS located near the galactic plane are labeled 1, 2 and 3 in white. The colorbar represents the stellar density, i.e., the number of stars having G ≥ 15 within a radius of 5 arcmin. -- astro-ph.HE

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Habitable Zones, Imaging & Spectroscopy, Stellar Cartography, Water/Hycean Worlds & Oceanography

The 10 pc Neighborhood of Habitable Zone Exoplanetary Systems: Threat Assessment from Stellar Encounters & Supernovae

by Keith CowingOctober 31, 2024October 31, 2024

Gerald A. Soffen -- NASA

Career Opportunities, Education and Outreach, NASA Astrobiology Program, People Of Astrobiology

Gerald A. Soffen Memorial Fund Fall 2024 Travel Grants

by Keith CowingOctober 31, 2024October 11, 2025