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Статті в журналах з теми "Temperate rocky planets"
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Unterborn, Cayman T., Bradford J. Foley, Steven J. Desch, Patrick A. Young, Gregory Vance, Lee Chiffelle, and Stephen R. Kane. "Mantle Degassing Lifetimes through Galactic Time and the Maximum Age Stagnant-lid Rocky Exoplanets Can Support Temperate Climates." Astrophysical Journal Letters 930, no. 1 (May 1, 2022): L6. http://dx.doi.org/10.3847/2041-8213/ac6596.
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Abstract The ideal exoplanets to search for life are those within a star’s habitable zone. However, even within the habitable zone, planets can still develop uninhabitable climate states. Sustaining a temperate climate over geologic (∼gigayear) timescales requires a planet to contain sufficient internal energy to power a planetary-scale carbon cycle. A major component of a rocky planet’s energy budget is the heat produced by the decay of radioactive elements, especially 40K, 232Th, 235U, and 238U. As the planet ages and these elements decay, this radiogenic energy source dwindles. Here we estimate the probability distribution of the amount of these heat-producing elements that enter into rocky exoplanets through Galactic history by combining the system-to-system variation seen in stellar abundance data with the results from Galactic chemical evolution models. From this, we perform Monte Carlo thermal evolution models that maximize the mantle cooling rate, thus allowing us to create a pessimistic estimate of lifetime a rocky, stagnant-lid exoplanet can support a global carbon cycle through Galactic history. We apply this framework to a sample of 17 likely rocky exoplanets with measured ages, seven of which we predict are likely to be actively degassing today, despite our pessimistic assumptions. For the remaining planets, including those orbiting TRAPPIST-1, we cannot confidently assume that they currently contain sufficient internal heat to support mantle degassing at a rate sufficient to sustain a global carbon cycle or temperate climate without additional tidal heating or undergoing plate tectonics.
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Dreizler, S., S. V. Jeffers, E. Rodríguez, M. Zechmeister, J. R. Barnes, C. A. Haswell, G. A. L. Coleman, et al. "RedDots: a temperate 1.5 Earth-mass planet candidate in a compact multiterrestrial planet system around GJ 1061." Monthly Notices of the Royal Astronomical Society 493, no. 1 (January 29, 2020): 536–50. http://dx.doi.org/10.1093/mnras/staa248.
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ABSTRACT Small low-mass stars are favourable targets for the detection of rocky habitable planets. In particular, planetary systems in the solar neighbourhood are interesting and suitable for precise characterization. The RedDots campaigns seek to discover rocky planets orbiting nearby low-mass stars. The 2018 campaign targeted GJ 1061, which is the 20th nearest star to the Sun. For three consecutive months we obtained nightly, high-precision radial velocity measurements with the HARPS spectrograph. We analysed these data together with archival HARPS data. We report the detection of three planet candidates with periods of 3.204 ± 0.001, 6.689 ± 0.005, and 13.03 ± 0.03 d, which are close to 1:2:4 period commensurability. After several considerations related to the properties of the noise and sampling, we conclude that a fourth signal is most likely explained by stellar rotation, although it may be due to a planet. The proposed three-planet system (and the potential four-planet solution) is long-term dynamically stable. Planet–planet gravitational interactions are below our current detection threshold. The minimum masses of the three planets range from 1.4 ± 0.2 to 1.8 ± 0.3 M⊕. Planet d, with msin i = 1.64 ± 0.24 M⊕, receives a similar amount of energy as Earth receives from the Sun. Consequently it lies within the liquid-water habitable zone of the star and has a similar equilibrium temperature to Earth. GJ 1061 has very similar properties to Proxima Centauri but activity indices point to lower levels of stellar activity.
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Luque, Rafael, and Enric Pallé. "Density, not radius, separates rocky and water-rich small planets orbiting M dwarf stars." Science 377, no. 6611 (September 9, 2022): 1211–14. http://dx.doi.org/10.1126/science.abl7164.
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Exoplanets smaller than Neptune are common around red dwarf stars (M dwarfs), with those that transit their host star constituting the bulk of known temperate worlds amenable for atmospheric characterization. We analyze the masses and radii of all known small transiting planets around M dwarfs, identifying three populations: rocky, water-rich, and gas-rich. Our results are inconsistent with the previously known bimodal radius distribution arising from atmospheric loss of a hydrogen/helium envelope. Instead, we propose that a density gap separates rocky from water-rich exoplanets. Formation models that include orbital migration can explain the observations: Rocky planets form within the snow line, whereas water-rich worlds form outside it and later migrate inward.
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Ding, Feng, and Robin D. Wordsworth. "Prospects for Water Vapor Detection in the Atmospheres of Temperate and Arid Rocky Exoplanets around M-dwarf Stars." Astrophysical Journal Letters 925, no. 1 (January 1, 2022): L8. http://dx.doi.org/10.3847/2041-8213/ac4a5d.
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Abstract Detection of water vapor in the atmospheres of temperate, rocky exoplanets would be a major milestone on the path toward characterization of exoplanet habitability. Past modeling work has shown that cloud formation may prevent the detection of water vapor on Earth-like planets with surface oceans using the James Webb Space Telescope (JWST). Here we analyze the potential for atmospheric detection of H2O on a different class of targets: arid planets. Using transit spectrum simulations, we show that atmospheric H2O may be easier to detect on arid planets with cold-trapped ice deposits on the surface because such planets will not possess thick H2O cloud decks that limit the transit depth of spectral features. However, additional factors such as band overlap with CO2 and other gases, extinction by mineral dust, overlap of stellar and planetary H2O lines, and the ultimate noise floor obtainable by JWST still pose important challenges. For this reason, a combination of space- and ground-based spectroscopic observations will be essential for reliable detection of H2O on rocky exoplanets in the future.
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Moore, Keavin, and Nicolas B. Cowan. "Keeping M-Earths habitable in the face of atmospheric loss by sequestering water in the mantle." Monthly Notices of the Royal Astronomical Society 496, no. 3 (June 20, 2020): 3786–95. http://dx.doi.org/10.1093/mnras/staa1796.
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ABSTRACT Water cycling between Earth’s mantle and surface has previously been modelled and extrapolated to rocky exoplanets, but these studies neglected the host star. M-dwarf stars are more common than Sun-like stars and at least as likely to host temperate rocky planets (M-Earths). However, M dwarfs are active throughout their lifetimes; specifically, X-ray and extreme ultraviolet (XUV) radiation during their early evolution can cause rapid atmospheric loss on orbiting planets. The increased bolometric flux reaching M-Earths leads to warmer, moister upper atmospheres, while XUV radiation can photodissociate water molecules and drive hydrogen and oxygen escape to space. Here, we present a coupled model of deep-water cycling and water loss to space on M-Earths to explore whether these planets can remain habitable despite their volatile evolution. We use a cycling parametrization accounting for the dependence of mantle degassing on seafloor pressure, the dependence of regassing on mantle temperature, and the effect of water on mantle viscosity and thermal evolution. We assume the M dwarf’s XUV radiation decreases exponentially with time, and energy-limited water loss with 30 per cent efficiency. We explore the effects of cycling and loss to space on planetary water inventories and water partitioning. Planet surfaces desiccated by loss can be rehydrated, provided there is sufficient water sequestered in the mantle to degas once loss rates diminish at later times. For a given water loss rate, the key parameter is the mantle overturn time-scale at early times: if the mantle overturn time-scale is longer than the loss time-scale, then the planet is likely to keep some of its water.
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Wells, R., K. Poppenhaeger, and C. A. Watson. "Validation of a temperate fourth planet in the K2-133 multiplanet system." Monthly Notices of the Royal Astronomical Society 487, no. 2 (May 16, 2019): 1865–73. http://dx.doi.org/10.1093/mnras/stz1334.
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Abstract We present follow-up observations of the K2-133 multiplanet system. Previously, we announced that K2-133 contained three super-Earths orbiting an M1.5V host star – with tentative evidence of a fourth outer-planet orbiting at the edge of the temperate zone. Here, we report on the validation of the presence of the fourth planet, determining a radius of $1.73_{-0.13}^{+0.14}$ R⊕. The four planets span the radius gap of the exoplanet population, meaning further follow-up would be worthwhile to obtain masses and test theories of the origin of the gap. In particular, the trend of increasing planetary radius with decreasing incident flux in the K2-133 system supports the claim that the gap is caused by photo-evaporation of exoplanet atmospheres. Finally, we note that K2-133 e orbits on the edge of the star's temperate zone, and that our radius measurement allows for the possibility that this is a rocky world. Additional mass measurements are required to confirm or refute this scenario.
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Lobo, Ana H., Aomawa L. Shields, Igor Z. Palubski, and Eric Wolf. "Terminator Habitability: The Case for Limited Water Availability on M-dwarf Planets." Astrophysical Journal 945, no. 2 (March 1, 2023): 161. http://dx.doi.org/10.3847/1538-4357/aca970.
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Abstract Rocky planets orbiting M-dwarf stars are among the most promising and abundant astronomical targets for detecting habitable climates. Planets in the M-dwarf habitable zone are likely synchronously rotating, such that we expect significant day–night temperature differences and potentially limited fractional habitability. Previous studies have focused on scenarios where fractional habitability is confined to the substellar or “eye” region, but in this paper we explore the possibility of planets with terminator habitability, defined by the existence of a habitable band at the transition between a scorching dayside and a glacial nightside. Using a global climate model, we show that for water-limited planets it is possible to have scorching temperatures in the “eye” and freezing temperatures on the nightside, while maintaining a temperate climate in the terminator region, due to reduced atmospheric energy transport. On water-rich planets, however, increasing the stellar flux leads to increased atmospheric energy transport and a reduction in day–night temperature differences, such that the terminator does not remain habitable once the dayside temperatures approach runaway or moist greenhouse limits. We also show that while water-abundant simulations may result in larger fractional habitability, they are vulnerable to water loss through cold trapping on the nightside surface or atmospheric water vapor escape, suggesting that even if planets were formed with abundant water, their climates could become water-limited and subject to terminator habitability.
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Laliotis, Katherine, Jennifer A. Burt, Eric E. Mamajek, Zhexing Li, Volker Perdelwitz, Jinglin Zhao, R. Paul Butler, et al. "Doppler Constraints on Planetary Companions to Nearby Sun-like Stars: An Archival Radial Velocity Survey of Southern Targets for Proposed NASA Direct Imaging Missions*." Astronomical Journal 165, no. 4 (March 27, 2023): 176. http://dx.doi.org/10.3847/1538-3881/acc067.
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Abstract Directly imaging temperate rocky planets orbiting nearby, Sun-like stars with a 6 m class IR/O/UV space telescope, recently dubbed the Habitable Worlds Observatory, is a high-priority goal of the Astro2020 Decadal Survey. To prepare for future direct imaging (DI) surveys, the list of potential targets should be thoroughly vetted to maximize efficiency and scientific yield. We present an analysis of archival radial velocity data for southern stars from the NASA/NSF Extreme Precision Radial Velocity (EPRV) Working Group’s list of high-priority target stars for future DI missions (drawn from the HabEx, LUVOIR, and Starshade Rendezvous studies). For each star, we constrain the region of companion mass and period parameter space we are already sensitive to based on the observational baseline, sampling, and precision of the archival radial velocity (RV) data. Additionally, for some of the targets, we report new estimates of magnetic activity cycle periods, rotation periods, improved orbital parameters for previously known exoplanets, and new candidate planet signals that require further vetting or observations to confirm. Our results show that for many of these stars we are not yet sensitive to even Saturn-mass planets in the habitable zone, let alone smaller planets, highlighting the need for future EPRV vetting efforts before the launch of a DI mission. We present evidence that the candidate temperate super-Earth exoplanet HD 85512b is most likely due to the star’s rotation, and report an RV acceleration for δ Pav that supports the existence of a distant giant planet previously inferred from astrometry.
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Krissansen-Totton, J., and J. J. Fortney. "Predictions for Observable Atmospheres of Trappist-1 Planets from a Fully Coupled Atmosphere–Interior Evolution Model." Astrophysical Journal 933, no. 1 (July 1, 2022): 115. http://dx.doi.org/10.3847/1538-4357/ac69cb.
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Abstract The Trappist-1 planets provide a unique opportunity to test the current understanding of rocky planet evolution. The James Webb Space Telescope is expected to characterize the atmospheres of these planets, potentially detecting CO2, CO, H2O, CH4, or abiotic O2 from water photodissociation and subsequent hydrogen escape. Here, we apply a coupled atmosphere–interior evolution model to the Trappist-1 planets to anticipate their modern atmospheres. This model, which has previously been validated for Earth and Venus, connects magma ocean crystallization to temperate geochemical cycling. Mantle convection, magmatic outgassing, atmospheric escape, crustal oxidation, a radiative-convective climate model, and deep volatile cycling are explicitly coupled to anticipate bulk atmospheres and planetary redox evolution over 8 Gyr. By adopting a Monte Carlo approach that samples a broad range of initial conditions and unknown parameters, we make some tentative predictions about current Trappist-1 atmospheres. We find that anoxic atmospheres are probable, but not guaranteed, for the outer planets; oxygen produced via hydrogen loss during the pre-main sequence is typically consumed by crustal sinks. In contrast, oxygen accumulation on the inner planets occurs in around half of all models runs. Complete atmospheric erosion is possible but not assured for the inner planets (occurs in 20%–50% of model runs), whereas the outer planets retain significant surface volatiles in virtually all model simulations. For all planets that retain substantial atmospheres, CO2-dominated or CO2–O2 atmospheres are expected; water vapor is unlikely to be a detectable atmospheric constituent in most cases. There are necessarily many caveats to these predictions, but the ways in which they misalign with upcoming observations will highlight gaps in terrestrial planet knowledge.
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Lingam, Manasvi, and Abraham Loeb. "Characteristics of aquatic biospheres on temperate planets around Sun-like stars and M dwarfs." Monthly Notices of the Royal Astronomical Society 503, no. 3 (March 4, 2021): 3434–48. http://dx.doi.org/10.1093/mnras/stab611.
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ABSTRACT Aquatic biospheres reliant on oxygenic photosynthesis are expected to play an important role on Earth-like planets endowed with large-scale oceans insofar as carbon fixation (i.e. biosynthesis of organic compounds) is concerned. We investigate the properties of aquatic biospheres comprising Earth-like biota for habitable rocky planets orbiting Sun-like stars and late-type M dwarfs such as TRAPPIST-1. In particular, we estimate how these characteristics evolve with the available flux of photosynthetically active radiation (PAR) and the ambient ocean temperature (TW), the latter of which constitutes a key environmental variable. We show that many salient properties, such as the depth of the photosynthesis zone and the net primary productivity (i.e. the effective rate of carbon fixation), are sensitive to PAR flux and TW and decline substantially when the former is decreased or the latter is increased. We conclude by exploring the implications of our analysis for exoplanets around Sun-like stars and M dwarfs.
Дисертації з теми "Temperate rocky planets"
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Dyrek, Achrène. "L'atmosphère des exoplanètes avec le James Webb Space Telescope." Electronic Thesis or Diss., Université Paris Cité, 2023. http://www.theses.fr/2023UNIP7096.
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Ma thèse est consacrée à l'étude des atmosphères d'exoplanètes avec le télescope spatial James Webb Space Telescope (JWST). L'étude et la caractérisation d'atmosphères d'exoplanètes représente aujourd'hui un enjeu majeur au sein de la communauté scientifique et au-delà, puisqu'il s'agit de mettre en perspective tous ces mondes découverts au cours des trois dernières décennies et notre propre Système solaire, seul hôte connu de la vie à ce jour. La première partie de ce manuscrit est consacrée à une introduction qui présente l'état de l'art de notre connaissance des atmosphères d'exoplanètes en termes de composition atomique et moléculaire, de structure et de dynamique. Cette introduction se concentre sur l'étude des atmosphères d'exoplanètes dites transitantes (lorsque la planète passe devant ou derrière son étoile dans l'axe de visée des télescopes) et fournit une description de cette méthode observationnelle ainsi que des défis associés. La deuxième partie de ce manuscrit s'intéresse à l'élaboration de simulations d'observations d'atmosphères d'exoplanètes à l'aide du Mid-InfraRed Instrument (MIRI) du JWST (à l'époque encore en attente de son lancement) et de son spectromètre basse résolution (LRS). Mon objectif principal est la conception d'un outil de simulation complet et robuste qui permette à la communauté de valider les méthodes de réduction de données et de prédire les détections moléculaires [Dyrek+, sub., 2023, Morello, Dyrek+, 2022]. La troisième partie de ce manuscrit est dédiée à l'étude des performances en vol du LRS de MIRI après le lancement du JWST, le jour de Noël 2021. En effet, l'arrivée des premières données du JWST marque le début d'une étape cruciale de ma thèse. En particulier, je m'appuie sur le premier transit exoplanétaire observé par MIRI, celui de la Super-Terre L168-9b, choisie comme cible pour l'étude des performances. A partir de ces données, je me suis concentrée sur l'identification de variations instrumentales infimes qui pourraient porter atteinte à la stabilité temporelle des observations. De fait, je discute des axes d'améliorations des méthodes de réduction de données dans le cadre de l'étude d'exoplanètes en transit [Dyrek+, sub., 2023]. La dernière partie de ce manuscrit est consacrée à l'analyse scientifique des courbes de lumières photométriques et spectroscopiques d'atmosphères d'exoplanètes, des géantes gazeuses aux rocheuses tempérées. Je présente mes travaux collaboratifs dans le cadre du Temps Garanti d'Observation (GTO) et de l'Early Release Science (ERS) du JWST pour lesquels j'ai mené la réduction et l'analyse des données. En particulier, je m'intéresse à la super-Neptune WASP-107b dont l'analyse de données a conduit notamment à la première détection de dioxyde soufre (SO2) en infrarouge moyen et à la première détection de nuages de silicates [Dyrek+, sub., 2023b]. Enfin, je présente la première détection de l'émission thermique d'une exoplanète rocheuse et tempérée, TRAPPIST-1b, pour laquelle nous avons contraint la température de brillance qui indique l'absence d'une atmosphère dense [Greene +, 2023]. Le chapitre final est dédié à l'ensemble des perspectives ouvertes par la révolution observationnelle du JWST et de la future mission dédiée aux exoplanètes : ArielMy thesis is devoted to the characterisation of exoplanet atmospheres with the newly-operating James Webb Space Telescope (JWST). Our understanding of exoplanet atmospheres is being revolutionised by the observational capabilities of such an observatory. The scientific outcomes will reach our scientific community and the general public, putting into perspective our knowledge of our own Solar System, the only system that is known to host life. The first part of this manuscript is devoted to an introduction that includes a state-of-the-art review of exoplanet atmospheres characterisation in terms of atomic and molecular composition, structure and dynamics. In this introduction, we focus on transiting exoplanets (when the planet passes in front of or behind its host star in the telescope's line of sight). We provide a description of this observational method and key results that have been obtained over the past two decades. The second part of this manuscript focuses on the molecular composition predictions with the JWST Mid-InfraRed Instrument (MIRI) and its Low-Resolution Spectrometer (LRS) that is meant to carry out atmospheric spectroscopy in an uncharted wavelength range. Here, we present realistic simulations of transiting exoplanets I developed during my thesis, with the MIRI LRS instrument that include various instrumental systematics likely to alter the atmospheric features we are meant to detect in our data [Dyrek+, sub., 2023, Morello, Dyrek+, 2022]. Our main objective is to design a comprehensive simulation tool that enables the community to build robust data reduction methods and to predict molecular detections. The third part of this manuscript is dedicated to the characterisation of the in-flight post-commissioning performances of the MIRI LRS. This work is based on the first exoplanetary transit observed with MIRI of the Super-Earth L168-9b, chosen to be a calibration target. My work focuses on identifying in-flight instrumental systematics that undermine observations' stability and more generally, the study of transiting exoplanets [Dyrek+, sub., 2023]. The final part of this manuscript is devoted to the scientific analysis of photometric and spectroscopic observations of both gas giants and temperate rocky exoplanet atmospheres. Here, I present my contribution on data reduction and analysis to the collaborative work we conducted as part of the Guaranteed Time Observation (GTO) and the Early Release Science (ERS) consortia. In particular, our work on the super-Neptune WASP-107b led to the first mid-infrared detection of sulphur dioxide (SO2) and silicate clouds [Dyrek+, sub., 2023b]. In addition, we conducted the first detection of the thermal emission of the rocky temperate exoplanet TRAPPIST-1b. In this work, we have constrained its brightness temperature, revealing key insights in the presence or not of an atmosphere [Greene+, 2023]. The final chapter of my thesis is dedicated to the prospects offered by JWST and the future Ariel mission, as these two telescopes will provide game-changing observations over the next decades
Книги з теми "Temperate rocky planets"
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1960-, Porembski S., and Barthlott Wilhelm, eds. Inselbergs: Biotic diversity of isolated rock outcrops in tropical and temperate regions. Berlin: Springer, 2000.
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Mineo, Baldassare. Rock garden plants: A color encyclopedia. Portland, Or: Timber Press, 1999.
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(Editor), S. Porembski, and W. Barthlott (Editor), eds. Inselbergs: Biotic Diversity of Isolated Rock Outcrops in Tropical and Temperate Regions. Springer, 2000.
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Noordin, Norazlina, Affrida Abu Hassan, Anis Nadia Mohd Faisol Mahadevan, Zaiton Ahmad, and Sakinah Ariffin. "Lab-Based Screening Using Hydroponic System for the Rapid Detection of Fusarium Wilt TR4 Tolerance/Resistance of Banana." In Efficient Screening Techniques to Identify Mutants with TR4 Resistance in Banana, 79–95. Berlin, Heidelberg: Springer Berlin Heidelberg, 2022. http://dx.doi.org/10.1007/978-3-662-64915-2_6.
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AbstractField-based screening and evaluation of banana plant tolerance or resistance to Fusarium oxysporum f. sp. cubense (Foc) Tropical Race 4 (TR4) or also known as Fusarium wilt TR4 is ideal though not always feasible. Alternatively, screening of banana plantlets at lab-stage seems to be an effective method for early detection of Foc TR4 tolerance. We present a simple hydroponic system, that allows plant to grow in a water-based condition. The system has two layers, the upper layer is a tray that has holes for plantlets to be placed where the root system is supported using an inert medium such as rock-wool. The lower layer is a perforated container filled with a water-based nutrient solution. For this lab-based screening, ex vitro gamma irradiated banana cv. Berangan (AAA) rooted plantlets with a pseudostem height of 10–15 cm were inoculated by soaking in a Foc TR4 conidial suspension (106 spores/ml) for 2 h under room temperature. The Foc TR4 inoculated rooted plantlets were screened using the hydroponic system and disease symptoms were scored. In this chapter, protocols on acclimatization of ex vitro irradiated rooted plantlets, inoculation with a Foc TR4 conidial suspension, lab- screening using hydroponic system, observation for early detection of disease symptoms and scoring of disease severity are presented.
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Anderson, Orson L. "Oxides that are Debye-Like Solids." In Equations of State of Solids for Geophysics and Ceramic Science, 113–56. Oxford University PressNew York, NY, 1995. http://dx.doi.org/10.1093/oso/9780195056068.003.0005.
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Abstract By physicists’ standards, the materials of planets are not well characterized. The material in the mantle of terrestrial planets is rocky and composed of many minerals that belong to a few phase diagrams. The large potential number of minerals in these phase diagrams is reduced and constrained by the density of seismological models. Even so, uniqueness is not possible because many minerals or combinations of minerals have the same density at zero pressure. Density discrimination at high pressure and high temperature could reduce the ambiguity further if the temperature of the planet were well characterized (which it is not), and if the equation of state were universally agreed upon (which it is not, as will be shown in Part II). Minerals that survive as candidates for planet interiors are of interest to ceramic science.
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Chambers, John, and Jacqueline Mitton. "Worlds of Rock and Metal." In From Dust to Life. Princeton University Press, 2017. http://dx.doi.org/10.23943/princeton/9780691175706.003.0009.
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This chapter explains how planetesimals—the basic building blocks of planets—are essentially invisible from here on Earth. To understand how planetesimals evolve into planets, one must examine material left over from planetary growth in the solar system, and make use of computer simulations. When planetesimals first formed, they were probably loosely bound mixtures of dust grains, chondrules, and other debris that happened to exist in the solar nebula at the time. As these planetesimals grew hot, volatile materials such as ices and organic tars would have melted and evaporated, ultimately making their way to the surface where they escaped into space. Some reactions between rock and water took place, but the temperature never rose high enough for rocky materials to melt, leaving behind planetesimals composed entirely of rock and metal.
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Alexander, Earl B., Roger G. Coleman, Todd Keeler-Wolfe, and Susan P. Harrison. "Synthesis and Future Directions." In Serpentine Geoecology of Western North America. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195165081.003.0031.
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Ultramafic rocks come from deep within the earth. Most rocks on the surface of the earth are quite different from them. Unique rocks make unique soils and support special plants. Exploring the links and interactions among these unique rocks, soils, and vegetation is an interdisciplinary endeavor that has been accomplished by experts in three areas. It has helped elucidate serpentine rock–soil–plant relationships and provide a rationale for the unusual soil properties and vegetation associated with ultramafic rocks. Examples from arctic tundra to temperate rainforest and hot desert in western North America provide a framework for the investigation of serpentine geoecosystems around the world. The unusual character of most serpentine vegetation is readily apparent even to an untrained eye. Although a vast number of rock and soil types make up the earth’s surface, few have as dramatic and visible effects on ecosystems as do ultramafic, or serpentine materials. Most ultramafic rocks in western North America have been derived from the mantle of earth via ocean crust. Magnesium is highly concentrated in the mantle and calcium, potassium, and phosphorous are relatively low. Calcium and potassium are further depleted from peridotite in the partial melting of ultramafic rock at the base of the ocean crust. As oceanic plates drift from spreading centers, most of the ocean crust is subducted and returns to the mantle (chapter 2). Only relatively small fragments of ocean crust are added to the continents. Because eukaryotic organisms, from protozoa to plants and animals, have evolved on continental crust, they are adapted to soils with higher concentrations of calcium, potassium, and phosphorus (elements with higher concentrations in continental crust than in ultramafic rocks from the base of the ocean crust) and much lower concentrations of magnesium. Having evolved on continents, plants depend on relatively high ratios of calcium and potassium to magnesium, elements that they use for a wide range of physiological functions. Although there has been a long history of evolutionary adaptation to the chemistry of the continental crust, special adaptations have allowed some plants to colonize the atypical conditions of serpentine.
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Thomson, Donald A., and Matthew R. Gilligan. "Rocky-Shore Fishes." In Island Biogeography in the Sea of Cortés II. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195133462.003.0013.
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Marine systems have provided little empirical or theoretical support for the equilibrium theory of island biogeography introduced by MacArthur and Wilson (1967; hereafter referred to as MacArthur-Wilson equilibria). In particular, although marine islands represent isolated habitats for shoreline-restricted marine organisms, it is clear that they do not have impoverished biotas relative to adjacent mainland shores as do their terrestrial counterparts. Additionally, it is not clear that colonization rates based on distance from propagule sources, and extinction rates based on island size, play a substantial role in determining the number and kind of species that may exist here. In this chapter we ask whether the gulf islands are biogeographic islands to rockyshore fishes as they are to terrestrial plants and animals. Although the adults and juveniles of most marine shore fishes cannot readily cross the deep waters separating landmasses, most marine fishes have pelagic eggs and larvae which are often found great distances from shore (Leis and Miller 1976; Leis 1991). Certain families of teleostean fishes (e.g., the blennioids and gobioids) have demersal eggs that are attached to a substrate, and only the larvae are dispersed by ocean currents. Some of these fishes have short-lived larvae that are normally found only close to shore (Brogan 1994). Considering such different types of dispersal mechanisms, one must conclude that distance over open water must be as formidable a barrier to dispersal in some fishes as it is to terrestrial organisms. In line with this conclusion, shore-fish faunas of oceanic islands show high degrees of endemism—for example, 23% in Galapagos shore fishes (Walker 1966), 23.1% and 22.2% in Hawaiian and Easter Island fishes, respectively (Randall 1998). It is well known that the marine insular environment differs considerably from the mainland or continental environment (Robins 1971). Essentially, the former is characterized by a more stable, predictable physical regime with moderate fluctuations in physical factors such as sea temperature, salinity, and turbidity, whereas the latter usually has wider and more unpredictable fluctuations in physical parameters. Robins (1971) compared the difference in species richness between insular and continental fish faunas of the tropical western Atlantic to that between a tropical and a temperate forest, respectively.
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Lahav, Noam. "Planet Earth." In Biogenesis, 132–40. Oxford University PressNew York, NY, 1999. http://dx.doi.org/10.1093/oso/9780195117547.003.0014.
Повний текст джерелаАнотація:
Abstract Except for major short-term perturbations in surface environments caused by a declining flux of impactors, equable conditions for prebiotic evolution could have existed as early as 4.4 GA. The earth is about 4.6 Ga old. At that remote time, known as the Hadean era (fig. 13.1), its surface was very hot as a result of the accretion process, which, according to recent hypotheses, took about a hundred million years: Its temperature, according to recent models, was about 1,500°K. Thus, the surface was molten. The iron-group elements (Fe, Ni, and Co) melted and passed through the lighter silicate molten rocks down beneath the crust in a process known as the iron catastrophe (R. F. Fox, 1988). Gradually the surface, rich in silicates, cooled down as the accretion energy input decreased. Solid rocks started to emerge, forming a thin scum, and a steam atmosphere began to condense and rain down to form the primordial oceans. Surface temperatures at or below l00°C could have developed as many as 4.4 Ga ago (Chang, 1993, 1994).are 3.8-3.9 billion years old, and there is no geological evidence of prebiotic organic chemical processes taking place on the earth’s surface prior to this time. Most of the very old rocks on Earth were transformed geologically by plate tectonics. Moreover, the early craters formed by impactors disappeared through erosion processes. Fortunately, despite the destruction of much of the geological record of primordial Earth, some of this evidence has been preserved and shown to be relevant to the study of the origin of life.
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Brosnan, Deborah M. "Ecology of tropical rocky shores: plant-animal interactions in tropical and temperate latitudes." In Plant-Animal Interactions in the Marine Benthos, 101–32. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198577546.003.0005.
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Abstract It is only the relative importance of various ecological processes that varies between tropical and temperate shores, not the processes themselves. A comparison of physical and biological features of tropical shores is presented. Overall, herbivorous fish are more common in the tropics, while invertebrate grazers dominate temperate regions; this difference is responsible for much of the variation in algal composition and abundance between tropical and temperate shores. A model predicting how different herbivores influence plant composition is presented. Nontrophic interactions are important at all latitudes, but may be more important in temperate zones. Three-dimensional refuges are more important in the tropics. Models of the importance of species interactions in relation to environmental stress may allow us to predict when plantanimal interactions will be dominant factors on rocky shores, regardless of latitude.
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Rothery, David A. "Active Worlds." In Satellites of the Outer Planets, 143–96. Oxford University PressNew York, NY, 1999. http://dx.doi.org/10.1093/oso/9780195125559.003.0007.
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Abstract Four satellites are regarded as active in this book: Io and Europa (Jupiter), Enceladus (Saturn), and Triton (Neptune). The occurrence of present-day activity on Europa and Enceladus can be disputed, but there is no doubt whatsoever in the case of Io. 7.1 10 Unlike the other satellites discussed in this book, Io does not have an icy surface (except for a sprinkling of sulfur dioxide frost). Its density and size are intermediate between those of the Moon and Mars, and in most respects it can be regarded as a terrestrial planet that happens to be in orbit around Jupiter. Jupiter’s influence is manifested by the elevated temperature in the inner part of the protojovian nebula that seems to have prevented a substantial amount of ice from accreting onto Io. Tidal heating caused by orbital resonance with Europa keeps Io’s interior hotter than it would otherwise now be in a rocky body of this size.
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Jolls, Claudia L. "Populations of and Threats to Rare Plants of the Herb Layer: More Challenges and Opportunities for Conservation Biologists." In The Herbaceous Layer in Forests of Eastern North America, 105–59. Oxford University PressNew York, NY, 2003. http://dx.doi.org/10.1093/oso/9780195140880.003.0005.
Повний текст джерелаАнотація:
Abstract In 1982, Paulette Bierzychudek presented a seminal review on population biology of shade-tolerant herbs of temperate deciduous forests. Her focus was largely on life histories, demography, and processes occurring at the population level,inspired,in part,by Harper’s (1977) treatise. In her opinion, our knowledge of herbs of particular forests was incomplete, particularly for coniferous forests, floodplains, rocky ledges, forested dunes, savannahs, and subtropical forests. Particular taxa were underrepresented in the literature as well. For example, at the time, no life-history study had yet been done on many shade-tolerant herbs that flower in later summer (Newell and Tramer 1978; Bierzychudek 1982a). Bierzychudek concluded that inadequate information existed for making generalizations about life histories of deciduous forest herbs, particularly their population growth rates or the temporal stability of their population sizes or structures.
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Keefer, Robert F. "Basic Information About Soils and Plants." In Handbook of Soils for Landscape Architects. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195121025.003.0004.
Повний текст джерелаАнотація:
All higher plants require the following factors for growth: . . . 1. Light 2. Heat* 3. Water* 4. Carbon Dioxide* 5. Oxygen* 6. Nutrients* 7. Mechanical Support* * Supplied by Soil or Soil Substitute. Except for light, all of these requirements are supplied by soil or a soil substitute; however, they must be supplied in the proper combination for best plant growth. Whichever of these is supplied below the optimum level will limit plant growth. Landscape architects need to determine which factor or factors limit growth and take measures to correct it. . . . WHAT IS SOIL? . . . “The soil” is a general term for the layer of the earth’s crust above the bedrock that has been weathered (physically and biochemically) by destructive and synthetic sources. “A soil” denotes a specific well-defined part of “the soil” with recognized properties and characteristics. There are thousands of different kinds of soils, and each individual soil has its own characteristics and responds to specific management. The name of a soil is associated with specified soil properties within stated limits. A few examples are Cecil clay loam, Marshall silt loam, and Norfolk sand. A number of factors have been involved in the formation of the soil and also of individual soils. The type of soils that have been formed depend on the nature of parent material (rocks and minerals), topography (lay of the land), climate (temperature and precipitation) whether or not living organisms are present, and geological time for formation. A change in any one or more of these soil-forming factors can have a profound effect on the specific “soil” that is formed. Is it any wonder that many diverse kinds of soil have been formed? In fact, branches of soil science called soil genesis and soil classification delve into this diversity in great detail. Soil Parent Material. Most soils are derived from the weathering of rocks and minerals. Exceptions to this are man-made soils and organic soils that are almost exclusively developed from organic matter.
Тези доповідей конференцій з теми "Temperate rocky planets"
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Sidhu, Charanpreet Singh, Zeinab El-Sayegh, and Alfonse Ly. "Non-pneumatic Tire-Mars Soil Interaction Using Advanced Computational Techniques." In WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2023. http://dx.doi.org/10.4271/2023-01-0022.
Повний текст джерелаАнотація:
<div class="section abstract"><div class="htmlview paragraph">The physical characteristics of Mars's soil have an impact on how easily a spacecraft can land and navigate the planet's surface. On the surface of Mars, wheeled robots known as "rovers" were planted to carry out scientific investigations on the planet's historical temperature, surface geology, and possibilities for past or current life. The challenges of guiding mobile robots across terrain that is sloping, rocky, and deformable have brought to light the significance of creating precise simulation models of the tire and mars soil interaction. In this paper, current efforts to create a terramechanics-based model of rover movement using a Non-Pneumatic (NP) tire on planetary surfaces are discussed. Since no rocks or soils have been brought back to Earth from Mars, Martian simulants are frequently used for testing rovers and other devices for Mars terrain research. Using a Finite Element Analysis-based NP tire model that is modeled and tested, in addition to a dry loose Martian soil that is modeled using Smoothed-Particle Hydrodynamics (SPH) technique and calibrated using pressure-sinkage and direct shear test. The rolling resistance coefficient on a Mars simulant can be investigated and analyzed. Results obtained from this research will validate the sustainability of NP tires for future Exploration of Mars.</div></div>
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Jemmal, Yousra, Nadia Zari, and Mohamed Maaroufi. "Study of rock suitability for high temperature thermal energy storage in concentrated solar tower power plants." In 2015 3rd International Renewable and Sustainable Energy Conference (IRSEC). IEEE, 2015. http://dx.doi.org/10.1109/irsec.2015.7455030.
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Agalit, Hassan, Soukaina Hrifech, El Ghali Bennouna, Abdelmajid Jarni, El Mostafa Mouguina, Yaroslav Grosu, Abdessamad Faik, and Abdelaziz Mimet. "Structural and thermophysical characterization of potential natural rocks for medium temperature thermal energy storage in CSP plants." In SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5117716.
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Lisabeth, H. P., N. Schmerr, V. Lekic, W. Zhu, M. Siegler, and R. Ghent. "The Effect of Moisture Content on the Acoustic Properties of Regolith Analogs." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0162.
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ABSTRACT Successful location of icy deposits on the moon and other planets requires detailed knowledge of the physical properties of both icy and ice-free potential reservoir materials in order to design geophysical equipment, implement surveys, and interpret data. In support of this goal, we have conducted acoustic characterization experiments to measure the physical properties of dry and icy regolith simulant using synchrotron x-ray transmission microtomography and ultrasonic acoustic sensing as a function of temperature. Measurements were performed on a porphyritic basaltic glass from a cinder cone. Synchrotron x-ray microtomography was performed at beamline 8.3.2 at the Advanced Light Source (ALS). Ultrasonic measurements were made on an ultrasonic pulse-transmission system consisting of an upright cylindrical acrylic column outfitted with ultrasonic and temperature sensors. Samples were cooled to −35°C and allowed to equilibrate. Ultrasonic measurements were then taken as the samples were slowly warmed. Waveforms from experiments were then analyzed to calculate changes in acoustic velocity and attenuation as a function of temperature. Oven dried samples show only slight variations in velocity with temperature, while slightly wet samples show significant variations, suggesting water on grain surfaces plays a significant role in the physical behavior of the samples. Further work is needed to address the temperature dependence of truly dry materials versus those with adsorbed volatiles; however, these initial results suggest that temperature-dependent acoustic measurements may be useful in the location of volatiles in regolith. INTRODUCTION There has been evidence for trace amounts of water trapped in lunar minerals for at least a decade (Saal et al., 2008), but more recent studies have identified signs that there may be free water stored as ice within the regolith (Schultz et al., 2010). Evidence for water in the lunar regolith from remote sensing shows that the lunar south pole in particular has a significant water resource (Sanin et al., 2017). Recent spectroscopic data suggest that there is between 100 and 400 mg/g of water in the regolith, much more than ever assumed (Honniball et al., 2020). The challenge will be to locate exactly where it sits in the regolith. Planetary science has always been driven by remote sensing, but as the US, other countries and private corporations ramp up robotic and manned missions to the moon in the next decade, direct, experimental measurement of the properties of icy regolith are needed.
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Makhnenko, R. Y., H. Kim, and K. Kim. "Thermal Effect on Long-Term Shale Behavior in Nuclear Waste Storage." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0908.
Повний текст джерелаАнотація:
ABSTRACT Shale-like formations can serve as barriers for geologic disposal of high-level nuclear waste. Adopting these tight materials has an advantage that any radionuclides emitted from the canisters would stay with hardly mobile pore water within the rock. However, there are a few issues associated with the sealing capacity of shales as high temperatures experienced in nuclear waste disposal can strongly affect their geomechanical and flow properties. In this study, we investigate how the continuous heating and hydromechanical loading are affecting the flow properties of a shale with the clay content above 50% and the dominant pore size on the order of tens of nanometers. Both intact and fractured specimens are considered, and parameters associated with a coupled hydromechanical model are measured in high-pressure laboratory experiments, including the time-dependent deformation introduced to the model through bulk viscosity. It appears that even a small increase in temperature from 24°C to 40°C significantly impacts long-term (viscoelastic) response of shale, while the effect on the short-term (poroelastic) behavior is less pronounced. At the same time, the thermal effect on the fluid flow is ambiguous: the permeability increases with temperature but is predicted to eventually decrease due to the accelerated rock compaction at elevated temperatures. INTRODUCTION Argillite geological formations have been considered worldwide as potential host rocks for geological disposal of high-level radioactive waste (HLW) because of their low permeability, high retention capacity for radionuclides, and capability to self-seal fractures (Sassani et al., 2021). Other favorable characteristics of argillites (often times represented by shales) are the strong sorptive behavior for many radionuclides reducing conditions because of the lack of oxygen transport from the surface, and chemical buffering of the effects caused by materials introduced during repository construction and operation (Tournassat et al., 2015; Urpi et al., 2019). One unfavorable feature of argillites compared to other potential host rock types is a relatively low thermal conductivity that would lead to higher host rock temperatures (potentially above 100 °C). This means that it will be crucial to gain reliable data for being able to confidently predict long-term, high-temperature responses of shaly host rock. This is exacerbated by the recent interest of disposal in large-sized canister of high decay heat that may lead to higher host rock temperature (Rutqvist, 2020). Moreover, with almost a hundred nuclear power plants across the US waiting for the permanent storage solutions, it is necessary to establish a procedure for obtaining properties of a wider range of typical argillites, from the more ductile materials with high clay content to more brittle rock that could respond vastly different when exposed to high temperature.
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Martin, Claudia, Nils Breidenbach, and Markus Eck. "Screening and Analysis of Potential Filler Materials for Molten Salt Thermocline Storages." In ASME 2014 8th International Conference on Energy Sustainability collocated with the ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/es2014-6493.
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Solar thermal power plants are a promising option for future solar electricity generation. Their main advantage is the possibility to utilize integrated thermal storage capacities, allowing electricity generation on demand. In state of the art solar thermal power plants, two-tank molten-salt thermal energy storages are used. Significant cost reductions are expected by using thermocline thermal energy storage by storing the liquid storage material inside a single tank when compared to a two tank storage system. By embedding a low cost solid filler material inside the storage tank further cost reductions can be achieved. In earlier studies [1, 2] several potential filler materials have been investigated. In these study quartzite turned out to be a promising candidate due to its satisfying thermal stability and availability. At a temperature of approx. 573°C the crystal structure of quartzite changes from trigonal α-quartz phase to the hexagonal β-quartz phase [3]. This quartz conversion results in a volume change [4] that may cause cracking of the quartzite crystals due to weight loads in a packed bed. Since these thermal tests of the study mentioned were limited to 500°C this dunting was not considered. Thus, despite of the published studies there is a need for further, more detailed analysis. One trend in today’s development of solar thermal power plants is to use molten salt as storage material and heat transfer fluid at operating temperatures of 560°C and above. Accordingly, the quartz inversion might limit the applicability of quartzite as a filler material at elevated operating temperatures. Due to this concern, an investigation has been started to investigate the utilizability of natural rocks as low cost filler materials. In the first phase of this investigation a comprehensive literature survey was conducted. Based on this study, magmatic and sedimentary rocks turned out to the most promising rock classes for this application. For the further investigation, basalt was chosen as a suited representative for magmatic and quartzite for sedimentary rocks. In lab-scale tests, these candidate materials were investigated with respect to their: • Calcite content • Thermal stability up to 900°C in air • Thermal stability up to 560°C in molten salt • Cyclic stability between 290°C and 560°C in molten salt • Specific heat capacity up to 600°C In this paper the results of these investigations are presented and future activities are outlined.
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Villaquiran Vargas, A. P., E. P. Knippel, Q. Xiong, and J. C. Hampton. "Experimental Evaluation of Flow Heterogeneity in Enhanced Geothermal Systems (EGS)." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0515.
Повний текст джерелаАнотація:
ABSTRACT Enhanced Geothermal Systems (EGS) are unconventional reservoirs with significant stored thermal energy and low hydraulic connectivity e.g., Hot Dry Rocks. To take advantage of these resources as a sustainable option, it is necessary to create and/or enhance existing fractures to achieve economic production rates. Laboratory-scale tests can assess critical knowledge gaps by conducting research under controlled conditions, allowing to understand mechanisms and then extrapolate them at the field scale, especially those contributing to, and controlling, flow heterogeneity. To that end, we use novel equipment that allows drilling, casing, stimulation, and multi-physics monitoring all under in-situ stress and temperature conditions, with multiple oriented wellbores and complex fracture networks connecting them. The laboratory EGS environments are assessed through acoustic emissions, foil strain gauges, fiber optic sensing, and tracer injection/recovery, measuring changes in stress, pressure, flow, and temperature, where fast-flowing channels that may lead to early thermal breakthrough affecting the heat recovery process can be identified and characterized. The experimental approach to mitigate the effects of flow channeling, is to design and evaluate different circulation schemes that minimize short-circuiting flow paths by adjusting specific operational parameters. During this first experimental stage, only surface control will be used since other strategies such as mechanical and chemical conformance control may not be suitable for EGS conditions. This paper provides a snapshot of a work-in-progress of the experimental results showing a single wellbore stimulation and hydraulic characterization in an unconfined Dakota granite. INTRODUCTION Geothermal Energy is considered a renewable energy resource since the rate of consumption is smaller than the renewing process rate - i.e., Just 1% of the total heat available in the Earth's crust is necessary to meet global energy needs; therefore, geothermal resources can provide energy to the planet for 2800 years at a constant consumption rate. Considering that this resource is continuously being renewed by various forms of heat received, it is a sustainable energy (Olasolo et al., 2016).
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Zhang, Guangfu, Shiming He, Ming Tang, Sen Liu, and Fuyuan Deng. "Effect of Fluid Invasion on the Failure and Deformation of Deep Coal and Wellbore Stability." In International Geomechanics Symposium. ARMA, 2022. http://dx.doi.org/10.56952/igs-2022-047.
Повний текст джерелаАнотація:
Abstract A large number of studies have shown that there are numerous cleavage planes and cracks in coal rock, and these weak planes are the main factors affecting the mechanical strength of coal rock. In order to quantitatively study the mechanism, rock samples were soaked in three kinds of fluids, namely "clean water", "original drilling fluid" and "new drilling fluid with strong plugging ability" and then these soaked samples and dry rock sample were respectively tested by high-temperature and high-pressure triaxial mechanical tester. The failure and deformation law of coal rock were quantitatively described, and the influence of confining pressure, cleavage plane and fluid on the mechanical parameters (cohesion, internal friction angle, elastic modulus, Poisson's ratio) was analyzed. A model for predicting the collapse pressure of coal seam considering the effects of seepage and multiple cleavage planes was established. The mechanical parameters of dry rock samples and the rock samples soaked in original drilling fluid and new drilling fluid were introduced into the model to quantitatively explain the impact of fluid invasion on coal rock formation collapse. Introduction The Jurassic strata in the northern Kuqa area of the Tarim Basin are deeply buried, and there are multiple sets of coal seams in the J2kz-J1y layers, with a burial depth of about 3600 m~4800 m1,2 ( Wang, D.2018; Mao J,1999) Well collapse, leakage and diameter expansion often occur, which seriously affect drilling speed and cementing quality in the later stage, and restrict oil and gas production. Studies have shown that during the diagenesis of coal, a large number of cleats will be formed in the coalification stage3,4(Jian, B,2001; Cao, 2021), and these cleats will reduce rock strength. The drilling fluid intrudes into the cleat in the drilling process due to pressure difference, thus playing a lubricating role to a certain extent5 (Chen, 2013), which further reduces the mechanical strength of the coal matrix block and cleat 6,7,8 ( Wang, 2020; Li, 2022; Han, 2022) and is even more unfavorable for wellbore stability9 ( Wang, 2010).
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Porlles, J. W., and H. Jabbari. "Simulation-Based Economical Modeling of Hydraulic Fracturing for Enhanced Geothermal System." In 56th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2022. http://dx.doi.org/10.56952/arma-2022-2326.
Повний текст джерелаАнотація:
ABSTRACT: Hydraulic fracturing is applied to extract fluids (oil, gas, and water) from very low permeability rocks. This type of stimulation could develop hot and dry rock geothermal resources. Habitually, those reservoirs are located in the depth of 2.7 Km to 5.5 Km; and at more than 180 °C. This study designs a hydraulic fracturing model in horizontal wells to extract hot water economically, creating high permeable artificial fractures. We aim to investigate the effects of varying fracture-cluster lengths, proppant, and frac fluid types, on hydraulic fracturing treatments using 2D and 3D simulation models. Some parameters such as type of proppant, fracture fluids, number of stages, fracture length, and fracture width are evaluated considering the reservoir’s high temperature and high pressure. Finally, different scenarios are evaluated to know if the hydraulic model is economically feasible to generate electricity with the current price of electricity price, drilling, and completion cost. 1. INTRODUCTION We perform an analysis to evaluate the feasibility of developing an enhanced geothermal system (EGS) project, considering the evaluation and modeling of a horizontal well stimulated by hydraulic fracturing, including fracture fluids and types of proppants that could be used in a frac job. The assessment covers a conceptual representation of a granitoid reservoir, considering a complete economic analysis including NPV, discount rate, reservoir temperature, number of horizontal wells, depth, and electricity sale price. The Department of Energy (DOE) generated an important report called "Geovision, Harnessing the Heat Beneath our feet". This report explains some scenarios concerning the geothermal industry and how will be the forecast for the next 30 years (DOE, 2019). Figure 1 presents the three scenarios explained in the report. The business-as-usual scenario (BAU) explains current and anticipated future trends if the geothermal industry continues on the exact forecast of 2015 conditions. Next, the Improved Regulatory Timeline (IRT) scenario estimates the impacts of reduced geothermal project development timelines and increased discovery rate of geothermal resources due to streamlined regulatory and permitting processes. Finally, the Technology Improvement (TI) scenario assesses the impacts of advanced technology developed aggressivity and the reduction of the cost of some technologies such as drilling, stimulation, logging, and power plants.
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Qu, Hai, Zhelun Li, Ying Liu, Zhijun Zeng, and Xu Liu. "Study on the Fracturing Pattern and Damage Characteristics of Deep Shale by Liquid Nitrogen Fracturing." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0375.
Повний текст джерелаАнотація:
ABSTRACT Liquid nitrogen (LN) can undermine the structure of the rock and its mechanical properties. It is also effective in engineering applications of deep resource exploitation. There are few lab experiments that use LN as a fracturing fluid directly. In this work, we have studied LN fracturing performances in deep shales under actual triaxial-confining stresses by a high-pressure LN fracturing device. Microcracks and matrix structures have been analyzed by scanning electron microscopy. The breakdown pressure and fracture morphologies have been compared with hydraulic fracturing. The result demonstrates that LN fracturing can obviously lower fracture initiation pressure and increase fracture complexity. The increase of differential stress ratio does not reduce fracture complexity. Microcracks and pore clusters can be induced on LN fracture surfaces, improving matrix permeability. Curved cracks, branched cracks, and horizontal bedding planes can be thermally induced around the borehole. Low fluid viscosity of LN can facilitate the fracture propagation and network generation during the fracturing process. The longer the bare-hole, the more thermally induced microcracks around the borehole, and the more complex macro fractures. Moreover, LN pretreatment can lower fracture initiation pressure actually. The productive findings obtained in this work are expected to provide an alternative for the sustainable development of deep shales resources. INTRODUCTION Deep shale gas resources below 3400 m are widely distributed and have the potential for sustainable natural gas development(Altammar et al., 2019).The deep shale formations have characteristics of low porosity and permeability and characterized by significant in-situ stresses, horizontal stress differences, and high temperature(Carpenter, 2017). Hydraulic fracturing is a traditional measure to stimulate these formations. However, the burden of hydraulic fracturing operations has been a topic of great importance to the energy industry and public alike(Han et al., 2018). Traditional hydraulic fracturing is challenging to generate complex fractures, and the production is usually less than expected (Cong et al., 2021). Cryogenic liquid nitrogen (LN, −196 °C at atmospheric pressure) fracturing is one possible method of solving these water-related issues(Yang et al., 2019). When LN is injected into the reservoir formation, the sudden heat transfer could cause shrinkage of the rock and exert a sharp thermal gradient that can induce numerous fractures at the surface of the formation rocks (Elwegaa et al., 2019). The significant thermal stress between LN and rock will lower fracture initiation pressure and create complex fractures(Wan et al., 2018). Therefore, LN fracturing will be an effective engineering method to develop high-temperature or deep formation resources(Wan et al., 2019).
Звіти організацій з теми "Temperate rocky planets"
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Leis, Sherry, Lloyd Morrison, and Tani Hubbard. Long-term trends in prairie vegetation at three national parks: 1998?2022. National Park Service, 2024. http://dx.doi.org/10.36967/2302359.
Повний текст джерелаАнотація:
The Heartland Inventory and Monitoring Network has monitored plant communities in National Parks since 1998. Three of those parks in the northern tier of the network?Herbert Hoover National Historic Site (NHS), Homestead National Historical Park (NHP), and Pipestone National Monument (NM)?have reconstructed tallgrass prairie communities and were sampled concurrently in 2022. In this combined report, we describe similarities and differences among the three parks related to current vegetation and trends. Climatically, Herbert Hoover NHS and Homestead NHP have similar temperature profiles, but Homestead NHP is drier. Pipestone NM differs from the other two parks in temperature and precipitation. Long-term climatic signals for major drought events varied by park, and moisture at Herbert Hoover NHS is likely to increase with climate change. Precipitation shifts could influence vegetation trends in the future requiring action such as flood mitigations, wildfire protections during prolonged drought, and consideration for species additions to adapt to new climate profiles. Plant composition was similar for Herbert Hoover NHS and Homestead NHP while the combination of plant species and abundances at Pipestone NM was different from the other two parks, especially within the Sioux Quartzite community type. There appeared to be some compositional shifts over time for Homestead NHP. That trend was supported by greater species turnover at Homestead NHP than the other two parks. The reconstruction at Homestead NHP is older than that of Herbert Hoover NHS and possibly Pipestone NM, but we are unable to determine the underlying causes of species changes. Quality assessment procedures provided a moderate level of confidence in our data with respect to botanist agreement on identifications. We met our goal of about 80% agreement in species composition. Cover class agreement was greater than?70%, with less than 4% of observations off by more than one class. Native species richness trends varied by park. Herbert Hoover NHS continues to gain native species while Pipestone NM is losing species. Species richness at Homestead NHP did not exhibit a directional trend. Pipestone NM tended to have less cover of forbs and grasses than the other two parks, reflecting the more complex geological landscape with surface rock. Grass abundance appears to be declining from baseline years for all three parks. Grass-like and fern guilds are much less abundant in all the parks than other plant guilds. Woody plants in 2022 were similar at Herbert Hoover NHS and Homestead NHP in terms of mean cover and heterogeneity across the prairies, but tree encroachment into the grasslands is a potential concern. Pipestone NM generally had fewer woody plants (including tree seedlings) in 2022, but the amount varied through time. Canopy closure, measured for the first time in 2022, was present in all three parks, but was greatest at Homestead NHP. Nonnative plant cover was the greatest at Pipestone NM, but current abundance at Herbert Hoover NHS was greater in 2022 than baseline years. Homestead NHP consistently had little nonnative plant cover since 2005. Abundance (% cover) of two nonnative grasses of concern?Kentucky bluegrass (Poa pratensis) and smooth brome (Bromus inermis)?differed by park and year. Recent increases in Kentucky bluegrass abundance at Herbert Hoover NHS might reflect changes in management. Although these parks have individual differences in climate as well as in timing and use of management actions, they share similar histories of cultivation and reconstruction. Efforts to restore or reconstruct portions of the prairie at Pipestone NM were unique among the three parks. Future analyses might continue to combine Herbert Hoover NHS and Homestead NHP but examine Pipestone NM separately; the unique geologic history and differences in vegetation communities at Pipestone NM may make individual assessment a better option. However, comparing trends in guilds of concern, such as woody and nonnative plants, across all three parks can be helpful for gauging success with management tools in light of regional changes in climate.
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Sanders, Suzanne, Jessica Kirschbaum, and Sarah Johnson. Arctic and alpine rare plant population dynamics at Isle Royale National Park: Response to changing lake levels. National Park Service, February 2022. http://dx.doi.org/10.36967/nrr-2291496.
Повний текст джерелаАнотація:
Arctic and alpine rare plant species populate wave-splashed rocky shorelines of Isle Royale National Park, where summer temperatures are moderated by Lake Superior. Using data from the mid-1990s and resurvey data from 1998, 2003, and 2016, we examined trajectories of change in occurrence for 25 species at 28 sites coincident with rising lake levels that followed a period of sustained low levels. We analyzed changes in site occupancy of species individually and by functional, geographic, and microhabitat groupings. We also assessed change in population structure for four focal species: Saxifraga paniculata, S. tricuspidata, Pinguicula vulgaris, and Vaccinium uliginosum. Of the 25 species, site occupancy increased for 13 and remained steady for six, declining in another six. Site occupancy did not change over time within functional, geographic, and microhabitat groupings. The four focal species showed similar dynamic and systematically changing populations, responding to similar ecological exposures. We hypothesize that the moderating influence of Lake Superior on air temperature benefits these populations despite warming temperatures and a 15-year sustained low water period. This work contributes to our understanding of the responses of at-risk species to extreme climate events.
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Leis, Sherry, and Lloyd Morrison. Plant community trends at Tallgrass Prairie National Preserve: 1998–2018. National Park Service, October 2022. http://dx.doi.org/10.36967/2294512.
Повний текст джерелаАнотація:
The Heartland Inventory and Monitoring Network monitors plant communities at Tallgrass Prairie National Preserve and evaluates a variety of environmental variables that affect vegetation patterns, including climate and ecological disturbances such as fire and grazing. Here we report on 2002–2018 trends in management actions (fire and grazing) and key plant community indicators. Temperature has increased over the past 50 years in the region. Precipitation and a standardized precipitation-evapotranspiration index included a high degree of interannual variability and did not demonstrate directional change. We documented a decline in disturbance intensity (i.e., less frequent prescribed fire and lower stocking rates) since 2006. A preserve goal is to maintain 30 to 60% of the area as bare ground (soil and rock) for ideal greater prairie-chicken habitat. Bare areas have been in decline and minimally meet the goal preserve wide. Bare areas vary by pasture and year, with bare areas exceeding the threshold in earlier years and Big Pasture and Red House Pasture falling short in some recent years. Although the preserve-scale mean minimally met the objective, there was a great deal of heterogeneity across monitoring sites. Litter cover and depth were greater than ecological recommendations for the greater prairie-chicken, especially in 2018. Litter depth demonstrated a great deal of variability and included deep litter. Woody plants were targeted to remain below 5% cover. Preserve- and pasture-scale cover means were well below this threshold but are increasing. Species richness on a per site basis (alpha diversity) and preserve-wide richness (gamma diversity) showed no apparent directional change when corrected for differences in sample size. Comparison of native species composition between 2002 and 2018 revealed a 36.9% difference in the Sørensen Index, although observer error accounted for almost 2/3 of this apparent change. The preserve continues to have characteristic tallgrass prairie species, and nonnative species continue to be low. Similar to targeted invasive plant monitoring, we found the target species Kentucky bluegrass to be below park thresholds. Continued evaluation of fire frequency and grazing intensity will be critical to achieving ecological goals including conserving the greater prairie-chicken. Development of a grazing plan may assist with prescribing stocking rates that are consistent with the preserve’s ecological and cultural objectives and could include alternative herbivores, such as goats or expansion of bison.
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Guidati, Gianfranco, and Domenico Giardini. Joint synthesis “Geothermal Energy” of the NRP “Energy”. Swiss National Science Foundation (SNSF), February 2020. http://dx.doi.org/10.46446/publication_nrp70_nrp71.2020.4.en.
Повний текст джерелаАнотація:
Near-to-surface geothermal energy with heat pumps is state of the art and is already widespread in Switzerland. In the future energy system, medium-deep to deep geothermal energy (1 to 6 kilometres) will, in addition, play an important role. To the forefront is the supply of heat for buildings and industrial processes. This form of geothermal energy utilisation requires a highly permeable underground area that allows a fluid – usually water – to absorb the naturally existing rock heat and then transport it to the surface. Sedimentary rocks are usually permeable by nature, whereas for granites and gneisses permeability must be artificially induced by injecting water. The heat gained in this way increases in line with the drilling depth: at a depth of 1 kilometre, the underground temperature is approximately 40°C, while at a depth of 3 kilometres it is around 100°C. To drive a steam turbine for the production of electricity, temperatures of over 100°C are required. As this requires greater depths of 3 to 6 kilometres, the risk of seismicity induced by the drilling also increases. Underground zones are also suitable for storing heat and gases, such as hydrogen or methane, and for the definitive storage of CO2. For this purpose, such zones need to fulfil similar requirements to those applicable to heat generation. In addition, however, a dense top layer is required above the reservoir so that the gas cannot escape. The joint project “Hydropower and geo-energy” of the NRP “Energy” focused on the question of where suitable ground layers can be found in Switzerland that optimally meet the requirements for the various uses. A second research priority concerned measures to reduce seismicity induced by deep drilling and the resulting damage to buildings. Models and simulations were also developed which contribute to a better understanding of the underground processes involved in the development and use of geothermal resources. In summary, the research results show that there are good conditions in Switzerland for the use of medium-deep geothermal energy (1 to 3 kilometres) – both for the building stock and for industrial processes. There are also grounds for optimism concerning the seasonal storage of heat and gases. In contrast, the potential for the definitive storage of CO2 in relevant quantities is rather limited. With respect to electricity production using deep geothermal energy (> 3 kilometres), the extent to which there is potential to exploit the underground economically is still not absolutely certain. In this regard, industrially operated demonstration plants are urgently needed in order to boost acceptance among the population and investors.
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Salcido, Charles, Patrick Wilson, Justin Tweet, Blake McCan, Clint Boyd, and Vincent Santucci. Theodore Roosevelt National Park: Paleontological resource inventory (public version). National Park Service, May 2022. http://dx.doi.org/10.36967/nrr-2293509.
Повний текст джерелаАнотація:
Theodore Roosevelt National Park (THRO) in western North Dakota was established for its historical connections with President Theodore Roosevelt. It contains not only historical and cultural resources, but abundant natural resources as well. Among these is one of the best geological and paleontological records of the Paleocene Epoch (66 to 56 million years ago) of any park in the National Park System. The Paleocene Epoch is of great scientific interest due to the great mass extinction that occurred at its opening (the Cretaceous–Paleogene extinction event), and the unusual climatic event that began at the end of the epoch (the Paleocene–Eocene Thermal Maximum, an anomalous global temperature spike). It is during the Paleocene that mammals began to diversify and move into the large-bodied niches vacated by dinosaurs. The rocks exposed at THRO preserve the latter part of the Paleocene, when mammals were proliferating and crocodiles were the largest predators. Western North Dakota was warmer and wetter with swampy forests; today these are preserved as the “petrified forests” that are one of THRO’s notable features. Despite abundant fossil resources, THRO has not historically been a scene of significant paleontological exploration. For example, the fossil forests have only had one published scientific description, and that report focused on the associated paleosols (“fossil soils”). The widespread petrified wood of the area has been known since at least the 19th century and was considered significant enough to be a tourist draw in the decades leading up to the establishment of THRO in 1947. Paleontologists occasionally collected and described fossil specimens from the park over the next few decades, but the true extent of paleontological resources was not realized until a joint North Dakota Geological Survey–NPS investigation under John Hoganson and Johnathan Campbell between 1994–1996. This survey uncovered 400 paleontological localities within the park representing a variety of plant, invertebrate, vertebrate, and trace fossils. Limited investigation and occasional collection of noteworthy specimens took place over the next two decades. In 2020, a new two-year initiative to further document the park’s paleontological resources began. This inventory, which was the basis for this report, identified another 158 fossil localities, some yielding taxa not recorded by the previous survey. Additional specimens were collected from the surface, among them a partial skeleton of a choristodere (an extinct aquatic reptile), dental material of two mammal taxa not previously recorded at THRO, and the first bird track found at the park. The inventory also provided an assessment of an area scheduled for ground-disturbing maintenance. This inventory is intended to inform future paleontological resource research, management, protection, and interpretation at THRO. THRO’s bedrock geology is dominated by two Paleocene rock formations: the Bullion Creek Formation and the overlying Sentinel Butte Formation of the Fort Union Group. Weathering of these formations has produced the distinctive banded badlands seen in THRO today. These two formations were deposited under very different conditions than the current conditions of western North Dakota. In the Paleocene, the region was warm and wet, with a landscape dominated by swamps, lakes, and rivers. Great forests now represented by petrified wood grew throughout the area. Freshwater mollusks, fish, amphibians (including giant salamanders), turtles, choristoderes, and crocodilians abounded in the ancient wetlands, while a variety of mammals representing either extinct lineages or the early forebearers of modern groups inhabited the land. There is little representation of the next 56 million years at THRO. The only evidence we have of events in the park for most of these millions of years is isolated Neogene lag deposits and terrace gravel. Quaternary surficial deposits have yielded a few fossils...