habitability Archives

100 TO These plots show the range of outcomes for oxygen accumulation (top row, green) and water retention (bottom row, blue) for the set of simulations with 100 TO initial water content on each of the planets. The distributions for the water behavior can be found in Figure 6, bottom row. Given 100 TO, all three planets are likely to retain water past 1 Gyr, making observations of water relatively likely. In addition, thousands of bars of oxygen may be produced for each planet in this scenario. Details on planet b’s behavior, similar to Figure 3, are given in Section 4. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report

Atmospheric Escape From Three Terrestrial Planets In The L 98-59 System

by Keith CowingDecember 4, 2023December 3, 2023

A critically important process affecting the climate evolution and potential habitability of an exoplanet is atmospheric escape, in which high-energy radiation from a star drives the escape of hydrogen atoms […]

Spectral signs of glint in phase-dependent observations of Earth. A full phase spectrum of Earth is corrected to crescent phase using a Lambert phase function (dark blue) and subtracted from a crescent phase spectrum of Earth (black) to produce a difference spectrum (grey). The result is well reproduced in window regions by a model that represents a solar spectrum that experiences Rayleigh scattering opacity (light blue) as it passes twice through the atmosphere and scatters once at the surface. -- astro-ph.EP

Exoplanets, -moons, -comets, Habitable Zones, Status Report, Water/Hycean Worlds & Oceanography

Characterizing Exoplanet Habitability

by Keith CowingNovember 20, 2023November 20, 2023

A habitable exoplanet is a world that can maintain stable liquid water on its surface. Techniques and approaches to characterizing such worlds are essential, as performing a census of Earth-like […]

(a) Surface temperature Ts (filled contours) for surface pressure ps = 5 bar and global mean surface optical depth τ = 5. The topography is plotted in blue dashed lines with a contour interval of 1000 m from 1000 m to 5000 m. The horizontal red dashed lines indicate the zone for tropical averaging (see Section 2.2). (b) Same as (a), but for the case with ps = 0.01 bar and τ = 0.01. The horizontal white dashed lines indicate the tropical averaging zone. (c) Relative surface lapse rate, γ (defined in Eq. 5), as a function of greenhouse effect, τ , and atmospheric thickness, ps. The data is sampled on a log-scale grid with τ = 0.003, 0.01, 0.1, 0.3, 1, 3, 5 and ps = 0.01, 0.1, 1, 5 bar. (d) The dependence of γ on τ when ps = 1 bar. Red solid (def): default simulation, obliquity equals zero, no atmospheric condensation, idealized topography, sensible heat flux enabled. Blue solid (obl20): as def, but with obliquity set to 20◦ . Blue dotted (atmo cond): as def, but with obliquity set to 20◦ , and a CO2-like atmospheric condensation is enabled. Magenta (MOLA): as def, but with Mars Orbiter Laser Altimeter topography. Cyan solid (w/o SH): as def, but with sensible heat flux disabled. Red dotted (2-column model): calculations from the simple two-column model (see Section 3.4). (e) As (d), but with varying ps and fixed τ = 0.1. Cyan dotted (fixed ρ in SH): as def, but the value of air density, ρ, is held fixed at the reference value for a 1-bar atmosphere in Eq. (3). -- astro-ph.EP

Arctic / Antarctic / Alpine, Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Habitable Zones, Status Report

Why Are Mountaintops Cold? The Transition Of Surface Lapse Rate on Dry Planets

by Keith CowingNovember 20, 2023November 20, 2023

Understanding surface temperature is important for habitability. Recent work on Mars has found that the dependence of surface temperature on elevation (surface lapse rate) converges to zero in the limit […]

A view of Mercury’s north polar chaotic terrain (Borealis Chaos) and the Raditladi and Eminescu craters where evidence of possible glaciers has been identified. Credit: NASA.

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Habitable Zones, Icy Worlds, Mercury, Press Release

Unveiling Mercury’s Geological Mysteries: Salt Glaciers, Primordial Atmosphere, and the New Frontiers of Astrobiology

by Keith CowingNovember 17, 2023November 17, 2023

Scientists from the Planetary Science Institute have uncovered evidence of potential salt glaciers on Mercury, opening a new frontier in astrobiology by revealing a volatile environment that might echo habitability […]

Responses of the atmospheric pCH4 to biogenic CH4 flux for the case of F-, G-, and Ktype stars (blue, black, and light blue solid lines with dots) (ExpCH4fluxF2V, ExpCH4fluxG2V, and ExpCH4fluxK2V in Table 3). The dotted lines represent the results of the case of the G-type star with the scaled intensity of the spectra at 200–210 nm (0.1, 0.5, 2, 10, and 40 times for purple, light purple, orange, red, and brown lines, respectively). (ExpCH4flux200nm in Table 3). -- astro-ph.EP

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

Controls of Atmospheric Methane on Early Earth and Inhabited Earth-like Terrestrial Exoplanets

by Keith CowingNovember 14, 2023November 14, 2023

Methane (CH4) is a primarily biogenic greenhouse gas. As such, it represents an essential biosignature to search for life on exoplanets.

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 […]

Available Gibbs Free Energy Posterior Distributions Inferred from Simulated Reflected Light Observations for Different Proterozoic Earth Models. a, The marginal posterior distribution of the log of the available Gibbs free energy for the high abundance case, derived from 20 (hatched), 30 (un-filled) and 50 (solid fill) SNR simulated reflected light observations. Vertical black (dashed), orange (dotted), red (dot-dashed), and blue (solid) lines in all three panels represent the input value and previously reported values for the available Gibbs free energy of modern Earth (atmosphere only case), Mars, and modern Earth (ME) (atmosphere-ocean case) respectively. b, Same as a but for the medium abundance case. c, Same as a but for the low abundance case. -- astro-ph.EP

Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

Inferring Chemical Disequilibrium Biosignatures for Proterozoic Earth-Like Exoplanets

by Keith CowingNovember 14, 2023November 14, 2023

Chemical disequilibrium quantified via available free energy has previously been proposed as a potential biosignature. However, exoplanet biosignature remote sensing work has not yet investigated how observational uncertainties impact the […]

The major subsystems of the Coronagraph Instrument.2 The optical bench sits above the electronics pallet. The Electronics Heat Transport System (EHTS) transports heat from the electronics to the warm radiator. The Cryogenic Thermal Subsystem provides passive cooling to the detectors. Multi-layer insulation (MLI) provides additional thermal shielding. The Instrument Carrier (IC) is the observatory structure to which Coronagraph is mounted. -- astro-ph.EP

Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report

Nancy Grace Roman Space Telescope Coronagraph Instrument Overview and Status

by Keith CowingNovember 12, 2023November 12, 2023

The Nancy Grace Roman Space Telescope Coronagraph Instrument is a critical technology demonstrator for NASA’s Habitable Worlds Observatory.

Boundaries of the Habitable Zone under various climate and atmospheric models as a function of radiative flux received from the host star, relative to Earth. Dashed lines represent the extended boundaries due to subglacial liquid water suggested in this work: blue for the inner HZ boundary (nightside ice evaporates due to heat transport, the percentage marks the global transport parameter f) and violet for the outer one (Martian polar lakes). Solid green lines and green shading denote the conservative HZ boundaries: inner one (moist greenhouse) and outer one (maximum CO2 greenhouse), calculated using the 1-D climate model. Also marked is the recent Venus boundary (dashed green line). The orange curve marks the tidal locking radius. Circles denote the terrestrial planets in the solar system and a few Earth-sized exoplanets orbiting M-dwarf stars. -- Hebrew University of Jerusalem

Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Press Release, Water/Hycean Worlds & Oceanography

Extended Habitability Of Exoplanets Due To Subglacial Water

by Keith CowingNovember 10, 2023November 10, 2023

Professor Amri Wandel, from Hebrew University of Jerusalem, has unveiled research that promises to redefine our comprehension of habitable exoplanets. In a recent study published in the Astronomical Journal, Professor […]

Negative life detections were cataloged from a wide range of potential biomes with vastly different physical and chemical conditions, occurring in aquatic and terrestrial settings. These sampling sites are often closely co-located with fully inhabited niches. The color of the dot identifies its biome genre. Where there are multiple dots overlapping, the number in parentheses after the location name indicates the number of separate sites.

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report

The Vacant Niche Revisited: Using Negative Results to Refine the Limits of Habitability

by Keith CowingNovember 8, 2023November 8, 2023

To define the boundaries of habitability, biologists often search for highly specialized organisms in extreme environments. However, negative life detections – when a method is unable to detect microorganisms in […]

habitability

Atmospheric Escape From Three Terrestrial Planets In The L 98-59 System

Characterizing Exoplanet Habitability

Why Are Mountaintops Cold? The Transition Of Surface Lapse Rate on Dry Planets

Unveiling Mercury’s Geological Mysteries: Salt Glaciers, Primordial Atmosphere, and the New Frontiers of Astrobiology

Controls of Atmospheric Methane on Early Earth and Inhabited Earth-like Terrestrial Exoplanets

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

Inferring Chemical Disequilibrium Biosignatures for Proterozoic Earth-Like Exoplanets

Nancy Grace Roman Space Telescope Coronagraph Instrument Overview and Status

Extended Habitability Of Exoplanets Due To Subglacial Water

The Vacant Niche Revisited: Using Negative Results to Refine the Limits of Habitability

How High-pressure Ices On Large Ocean Worlds Can Support Habitability: The Compatibility Of Amino Acids Into Ice VI And VII

Ice Drives The Emergence Of Functional Protocells

Chemical Abundance Patterns at z=1-7: Carbon, Nitrogen, Neon, Sulphur, and Argon Abundances From JWST Spectroscopy

Optimization of Petal-Shaped Occulters for Exo-Earth Observation

Topographically Forced Stationary Waves Can Explain The Near-Surface Zonal Winds Observed By Huygens On Titan