Venus, an Astrobiology Target

Limaye, S. S.; Mogul, Rakesh; Baines, K. H.; Bullock, M. A.; Cockell, Charles S.; Cutts, J. A.; Gentry, Diana; Grinspoon, David; Head, J. W.; Jessup, Kandis-Lea; Kompanichenko, Vladimir; Lee, Yeon Joo; Mathies, Richard A.; Milojevic, Tetyana; Pertzborn, R. A.; Rothschild, Lynn J.; Sasaki, Satoshi; Schulze‐Makuch, Dirk; Smith, David J.; Way, Michael

doi:10.1089/ast.2020.2268

Cited by 48 publications

(25 citation statements)

References 253 publications

(337 reference statements)

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“…The mean energy of muons at the ground under contemporary conditions is ∼ 4 GeV which is enough to penetrate a few meters of rock and several hundred meters of ice [963]. In worlds with very dense atmospheres, such as Titan and Venus, polarized muons dominate the radiation at altitudes around 50 km (and interestingly this is the habitable layer in Venus clouds [965]). The surface irradiation, comparable to that below 400 m of rock, is negligible.…”

Section: Astrobiologymentioning

confidence: 99%

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Coleman,

Eser,

Mayotte

et al. 2022

Preprint

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Pin down the shower energy observable to use μ as a composition-only Reduce hadronic uncertainties interaction model E threshold (TBD) Other messengers Galactic * μ / em separation † * depending on analysis progress † depending on detector configuration• At least one next-generation experiment needs to be able to make high-precision measurements to explore new particle physics and measure particle rigidity on an event-by-event basis. Of the planned next-generation experiments, GCOS is the best positioned to meet this recommendation.• As a complementary effort, experiments with sufficient exposure ( 5 × 10 5 km 2 sr yr) are needed to search for Lorentz-invariance violation (LIV), SHDM, and other BSM physics at the Cosmic and Energy Frontiers, and to identify UHECR sources at the highest energies.• Full-sky coverage with low cross-hemisphere systematic uncertainties is critical for astrophysical studies. To this end, next generation experiments should be space-based or multi-site. Common sites between experiments are encouraged.• Based on the productive results from inter-collaboration and inter-disciplinary work, we recommend the continued progress/formation of joint analyses between experiments and with other intersecting fields of research (e.g., magnetic fields).• The UHECR community should continue its efforts to advance diversity, equity, inclusion, and accessibility. It also needs to take steps to reduce its environmental impacts and improve open access to its data to reduce the scientific gap between countries.vi

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Section: Astrobiologymentioning

confidence: 99%

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Coleman,

Eser,

Mayotte

et al. 2022

Preprint

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“…Solar irradiances calculated across Venus' clouds support the potential for Earth-like phototrophy, while treatment of Venus' aerosols as containing neutralized sulfuric acid favors a habitable zone in the clouds. To date, most studies suggest that the aerosols in Venus' middle and lower clouds harbor high acidities (Seager et al, 2020;Limaye et al, 2021) with commensurate low water activities or availabilities (Cockell, 1999;Izenberg et al, 2020;Seager et al, 2020;Cockell et al, 2021;Hallsworth et al, 2021;Limaye et al, 2021). In contrast, as presented in this study, alternative interpretations to in situ measures yield potentially habitable conditions with water activities ( ‡0.585) and buffered acidities (Hammett acidity factor, H 0 -0.1 to -1.5) that lie within the limits of terrestrial microbial growth.…”

Section: Discussionmentioning

confidence: 99%

Potential for Phototrophy in Venus' Clouds

et al. 2021

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We show that solar irradiances calculated across Venus' clouds support the potential for Earth-like phototrophy and that treatment of Venus' aerosols containing neutralized sulfuric acid favor a habitable zone. The phototrophic potential of Venus' atmosphere was assessed by calculating irradiances (200-2000 nm, 15°solar zenith angle, local noon) using a radiative transfer model that accounted for absorption and scattering by the major and minor atmospheric constituents. Comparisons to Earth's surface (46 W m -2 , 280-400 nm) suggest that Venus' middle and lower clouds receive *87% less normalized UV flux (6-7 W m -2 ) across 200-400 nm, yet similar normalized photon flux densities (*4400-6200 mmol m -2 s -1 ) across 350-1200 nm. Further, Venus' signature phototrophic windows and subwindows overlap with the absorption profiles of several photosynthetic pigments, especially bacteriochlorophyll b from intact cells and phycocyanin. Therefore, Venus' light, with limited UV flux in the middle and lower clouds, is likely quite favorable for phototrophy. We additionally present interpretations to refractive index and radio occultation measures for Venus' aerosols that suggest the presence of lower sulfuric abundances and/or neutralized forms of sulfuric acid, such as ammonium bisulfate. Under these considerations, the aerosols in Venus' middle clouds could harbor water activities ( ‡0.6) and buffered acidities (Hammett acidity factor, H 0 -0.1 to -1.5) that lie within the limits of acidic cultivation ( ‡H 0 -0.4) and are tantalizingly close to the limits of oxygenic photosynthesis ( ‡H 0 0.1). Together, these photophysical and chemical considerations support a potential for phototrophy in Venus' clouds.

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“…Other than Mars, several places have also been cited and discussed as targets for extraterrestrial life exploration. Icy bodies, especially places with subsurface oceans and/or ejected plumes, such as Enceladus and Europa, are interesting places, as well as Venus' atmosphere, whose habitability of the environment and possibility of life relative to phosphine detection were recently investigated (Greaves et al 2020;Limaye et al 2021;Porco et al 2006).…”

Section: Mars and Other Placesmentioning

confidence: 99%

Extraterrestrial Life Signature Detection Microscopy: Search and Analysis of Cells and Organics on Mars and Other Solar System Bodies

et al. 2022

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This paper presents a review of the space exploration for life signature search with a special focus on the fluorescence microscope we developed for the life signature search on Mars and in other sites. Considering where, what, and how to search for life signature is essential. Life signature search exploration can be performed on the Mars surface and underground, on Venus’ cloud, moon, asteroids, icy bodies (e.g., moons of Jupiter and Saturn), and so on. It is a useful strategy to consider the targeted characteristics that may be similar to those of terrestrial microorganisms, which are microorganisms with uniform spherical or rod structures with approximately 1 μm diameter surrounded by a membrane having a metabolic activity and mainly made of carbon-based molecules. These characteristics can be analyzed by using a fluorescence microscope and a combination of fluorescence pigments with specific staining characteristics to distinguish the microorganism characteristics. Section 1 introduces the space exploration for life signature search. Section 2 reviews the scientific instruments and achievements of past and ongoing Mars exploration missions closely related to astrobiology. Section 3 presents the search targets and analysis of astrobiology. Section 4 discusses the extraterrestrial life exploration methods that use a microscope together with other methods (based on mass spectrometry, morphology, detection of growth, movement, and death, etc. for microscopic and macroscopic organism). Section 5 expounds on the life signature detection fluorescence microscope, for which we have manufactured a bread board model and tested for extraterrestrial life exploration.

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Venus, an Astrobiology Target

Cited by 48 publications

References 253 publications

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

Potential for Phototrophy in Venus' Clouds

Extraterrestrial Life Signature Detection Microscopy: Search and Analysis of Cells and Organics on Mars and Other Solar System Bodies

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