Archean Earth Archives

Away Teams & Field Reports, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Caves, Craters, Mountains, Subsurface, Lava Tubes, Habitable Zones, Impact events, Meteorites & Asteroids, Origin & Evolution of Life, Press Release, Sample Return

Experimental and Numerical Modeling of Liposome Congregation in Meteorite Craters of Early Earth

by Keith CowingApril 29, 2026April 29, 2026

This paper provides experimental and numerical evidence supporting the occurrence of liposome congregation at the floors of meteor craters on Early Earth.

In the top panel, we present a representative spectrum from our work where molecular contributions are visible, with the y-axis representing the geometric albedo. In the bottom panel, we present the absorbance contributions of every molecule available in the KEN grids, as well as the Rayleigh scattering also included: H2O, O2, O3, CH4, CO, CO2, SO2, and N2O, with the y-axis representing absorption. The x-axes are both the full wavelength range of the KEN grids (0.2–2µm). Note that SO2 and N2O absorb at 0.2 µm very minimally, without features in other locations in this wavelength range. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

Bayesian Analysis for Remote Biosignature Identification on exoEarths (BARBIE) III: Introducing the KEN

by Keith CowingNovember 25, 2024November 25, 2024

We deploy a newly-generated set of geometric albedo spectral grids to examine the detectability of methane (CH4) in the reflected-light spectrum of an Earth-like exoplanet at visible and near-infrared wavelengths […]

Flux contrast ratio of an Archean Earthlike planet with CO/CH4 = 10 as a function of wavelength. The input forward model is shown by the red circles, and the retrieval result is overlain and separated by molecule to show the individual molecular contributions. -- astro-ph.EP

The Detectability of CH4/CO2/CO and N2O Biosignatures through Reflection Spectroscopy of Terrestrial Exoplanets

by Keith CowingOctober 22, 2024October 22, 2024

The chemical makeup of Earth’s atmosphere during the Archean (4 Ga-2.5 Ga) and Proterozoic eon (2.5 Ga-0.5 Ga) contrast considerably with the present-day: the Archean was rich in carbon dioxide […]

A schematic of the saddle node bifurcation in the carbon cycle suggested by our simulations. The blue curve represents the global weathering rate as a function of pCO2. Weathering increases with increasing pCO2 (and surface temperature) in the green zone, and it decreases with increasing pCO2 (and surface temperature) in the red zone. Weathering rates are equal to outgassing (V ) at pCO2=P1 (orange) and at pCO2=P2 (black). The P1 equilibrium is stable because weathering acts as a negative feedback in that regime, while the P2 equilibrium is unstable due to silicate weathering’s positive feedback behavior. The red arrows indicate the directions CO2 and weathering would evolve for a climate intialized from various points relative to the two equilibria. -- astro-ph.EP

Astrochemistry, Astrogeology, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report, Water/Hycean Worlds & Oceanography

Carbon Cycle Instability For High-CO2 Exoplanets: Implications For Habitability

by Keith CowingMay 10, 2024May 10, 2024

Implicit in the definition of the classical circumstellar habitable zone (HZ) is the hypothesis that the carbonate-silicate cycle can maintain clement climates on exoplanets with land and surface water across […]

Schematic representation of oxygenic photosynthesis and the generation of superoxide during the day inside a Cyanobacterial cell. The thylakoid membrane contains Photosystem II (PSII) connected to phycobilisomes, Photosystem I (PSI), cytochrome b6f (cyt b6f), and electron transporters plastoquinone (PQ) and plastocyanin (PC). Phycobilisomes capture light energy and transfer it to PSII resulting in the hydrolysis of water and transfer of electrons to PQ, with the concomitant generation of molecular oxygen (O2) and protons (H+ ). PQ then transfers the electrons to PSI via cyt b6f and PC, thereby translocating two protons (2H+ ) across the thylakoid membrane, into the lumen. The resulting proton gradient powers the synthesis of adenosine triphosphate (ATP) via ATP synthase. PSI transfers electrons to ferredoxin (Fd), that in turn transfers electrons to ferredoxin NADP+ oxidoreductase (FNR) to generate reduced nicotinamide adenine dinucleotide phosphate (NADPH). Both NADPH and ATP are used to power cellular processes, such as CO2 fixation (Mullineaux, 2014). Increased light exposure may result in excess electrons being fed into the electron transport chain, resulting in the generation of superoxide (O2 •– ) (Latifi et al., 2009). Dismutation of O2 •– to hydrogen peroxide (H2O2) potentially occurs in different species via superoxide dimutases (SODs), in the cytoplasm, thylakoid lumen or periplasmic space (Herbert et al., 1992; Li et al., 2002; Napoli et al., 2021; Raghavan et al., 2013; Raghavan et al., 2015). Image generated in Biorender ©. -- biorxiv.org

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Genomics, Proteomics, Bioinformatics, Microbiology & Virology, Origin & Evolution of Life, Status Report

Early-branching Cyanobacteria Up-regulate Superoxide Dismutase Activity Under A Simulated Early Earth Anoxic Atmosphere

by Keith CowingMarch 17, 2024

The evolution of oxygenic photosynthesis during the Archean (4-2.5 Ga), required the presence of complementary reducing pathways to maintain the cellular redox balance.

Modeled Haze free Archean Earth Spectrum. Shown here is the planet-to-star flux ratio vs wavelength and in black is the simulated spectrum for a haze free Archean Earth-like planet around the sun. The spectral bandpasses from the Archean Earth pathway on the decision tree are shown where the 0.89 µm bandpass is shaded in green and the 1.65 µm bandpass is shaded in red. The Rayleigh scattering slope and species absorption features are labeled in text. Also shown is an SNR 10 error bar scaling indicative of the simulated observations for each singular bandpass and combination. -- astro-ph.EP

Analog Studies, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

Retrievals Applied To A Decision Tree Framework Can Characterize Earth-like Exoplanet Analogs

by Keith CowingNovember 14, 2023November 14, 2023

Exoplanet characterization missions planned for the future will soon enable searches for life beyond our solar system. Critical to the search will be the development of life detection strategies that […]

Particle number density in cm−3 (left) and particle radius in µm (right) from Atmos, for each of the haze profiles. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Fossils & Paleontology, Status Report

3D Simulations Of The Archean Earth Including Photochemical Haze Profiles

by Keith CowingOctober 11, 2023October 11, 2023

We present results from 3D simulations of the Archean Earth including a prescribed (non-interactive) spherical haze generated through a 1D photochemical model.

Biosignatures & Paleobiology, Press Release

The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth

by Keith CowingOctober 17, 2016

Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions […]

Archean Earth

Experimental and Numerical Modeling of Liposome Congregation in Meteorite Craters of Early Earth

Bayesian Analysis for Remote Biosignature Identification on exoEarths (BARBIE) III: Introducing the KEN

The Detectability of CH4/CO2/CO and N2O Biosignatures through Reflection Spectroscopy of Terrestrial Exoplanets

Carbon Cycle Instability For High-CO2 Exoplanets: Implications For Habitability

Early-branching Cyanobacteria Up-regulate Superoxide Dismutase Activity Under A Simulated Early Earth Anoxic Atmosphere

Retrievals Applied To A Decision Tree Framework Can Characterize Earth-like Exoplanet Analogs

3D Simulations Of The Archean Earth Including Photochemical Haze Profiles

The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth

NASA Spaceline Current Awareness List #1,205 26 June 2026 (Space Life Science Research Results)

PJ Harvey Announces New Song “Voyager”

Searching For Extraterrestrial Intelligence With The SKA

Mars Perseverance Image of the Week for Week 280 (June 21 – 27, 2026)

The Earthling Ovary Blueprint Is Ancient According To Sea Stars