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1
Rovira-Navarro, Marc, Isamu Matsuyama, and Hamish C. F. C. Hay. "Thin-shell Tidal Dynamics of Ocean Worlds." Planetary Science Journal 4, no. 2 (February 1, 2023): 23. http://dx.doi.org/10.3847/psj/acae9a.
Анотація:
Abstract Several solar system moons harbor subsurface water oceans; extreme internal heating or solar irradiation can form magma oceans in terrestrial bodies. Tidal forces drive ocean currents, producing tidal heating that affects the thermal−orbital evolution of these worlds. If the outermost layers (ocean and overlying shell) are thin, tidal dynamics can be described using thin-shell theory. Previous work assumed that the ocean and shell's thickness and density are uniform. We present a formulation of thin-shell dynamics that relaxes these assumptions and apply it to several cases of interest. The tidal response of unstratified oceans of constant thickness is given by surface gravity and Rossby waves, which can resonate with the tidal force. The oceans of the outer solar system are too thick for gravity wave resonances, but high-amplitude Rossby waves can be excited in moons with high orbital obliquity. We find that meridional ocean thickness variations hinder the excitation of Rossby waves, decreasing tidal dissipation and increasing the inclination damping timescale, which allows us to reconcile the present inclination of the Moon with the existence of a past long-lived magma ocean and to explain the inclination of Titan and Callisto without invoking a recent excitation. Stratified oceans can support internal gravity waves. We show that dissipation due to internal waves can exceed that resulting from surface gravity waves. For Enceladus, it can be close to the moon’s thermal output, even if the ocean is weakly stratified. Shear due to internal waves can result in Kelvin–Helmholtz instabilities and induce ocean mixing.
2
Jansen, Malte F., Wanying Kang, Edwin S. Kite, and Yaoxuan Zeng. "Energetic Constraints on Ocean Circulations of Icy Ocean Worlds." Planetary Science Journal 4, no. 6 (June 1, 2023): 117. http://dx.doi.org/10.3847/psj/acda95.
Анотація:
Abstract Globally ice-covered oceans have been found on multiple moons in the solar system and may also have been a feature of Earth’s past. However, relatively little is understood about the dynamics of these ice-covered oceans, which affect not only the physical environment but also any potential life and its detectability. A number of studies have simulated the circulation of icy-world oceans, but have come to seemingly widely different conclusions. To better understand and narrow down these diverging results, we discuss the energetic constraints for the circulation on ice-covered oceans, focusing in particular on Snowball Earth, Europa, and Enceladus. The energy input that can drive ocean circulation on ice-covered bodies can be associated with heat and salt fluxes at the boundaries as well as ocean tides and librations. We show that heating from the solid core balanced by heat loss through the ice sheet can drive an ocean circulation, but the resulting flows would be relatively weak and strongly affected by rotation. Salt fluxes associated with freezing and melting at the ice sheet boundary are unlikely to energetically drive a circulation, although they can shape the large-scale circulation when combined with turbulent mixing. Ocean tides and librations may provide an energy source for such turbulence, but the magnitude of this energy source remains highly uncertain for the icy moons, which poses a major obstacle to predicting the ocean dynamics of icy worlds and remains an important topic for future research.
3
Castillo-Rogez, Julie C., and Klára Kalousová. "Ocean Worlds In Our Solar System." Elements 18, no. 3 (June 1, 2022): 161–66. http://dx.doi.org/10.2138/gselements.18.3.161.
Анотація:
Spacecraft-based missions have discovered an increasing number of ocean worlds in our Solar System, with even more candidates awaiting confirmation. The science of ocean worlds shares some commonalities with that of Earth’s oceans, making them exciting targets of future exploration. A major known difference, however, is that ice shells up to tens of kilometers thick may present barriers to the introduction of chemical gradients necessary for life’s development over the long term. Hence, ocean worlds differ substantially in terms of their energy budget and chemistry, with Europa and Enceladus being currently considered the most promising candidates for life-search missions.
4
Rigby, Frances E., and Nikku Madhusudhan. "On the ocean conditions of Hycean worlds." Monthly Notices of the Royal Astronomical Society 529, no. 1 (February 27, 2024): 409–24. http://dx.doi.org/10.1093/mnras/stae413.
Анотація:
ABSTRACT Recent studies have suggested the possibility of Hycean worlds, characterized by deep liquid water oceans beneath H2-rich atmospheres. These planets significantly widen the range of planetary properties over which habitable conditions could exist. We conduct internal structure modelling of Hycean worlds to investigate the range of interior compositions, ocean depths and atmospheric mass fractions possible. Our investigation explicitly considers habitable oceans, where the surface conditions are limited to those that can support potential life. The ocean depths depend on the surface gravity and temperature, confirming previous studies, and span 10s to ∼1000 km for Hycean conditions, reaching ocean base pressures up to ∼6 × 104 bar before transitioning to high-pressure ice. We explore in detail test cases of five Hycean candidates, placing constraints on their possible ocean depths and interior compositions based on their bulk properties. We report limits on their atmospheric mass fractions admissible for Hycean conditions, as well as those allowed for other possible interior compositions. For the Hycean conditions considered, across these candidates we find the admissible mass fractions of the H/He envelopes to be ≲10−3. At the other extreme, the maximum H/He mass fractions allowed for these planets can be up to ∼4–8 per cent, representing purely rocky interiors with no H2O layer. These results highlight the diverse conditions possible among these planets and demonstrate their potential to host habitable conditions under vastly different circumstances to the Earth. Upcoming JWST observations of candidate Hycean worlds will allow for improved constraints on the nature of their atmospheres and interiors.
5
Boström, Mathias, Victoria Esteso, Johannes Fiedler, Iver Brevik, Stefan Yoshi Buhmann, Clas Persson, Sol Carretero-Palacios, Drew F. Parsons, and Robert W. Corkery. "Self-preserving ice layers on CO2 clathrate particles: Implications for Enceladus, Pluto, and similar ocean worlds." Astronomy & Astrophysics 650 (June 2021): A54. http://dx.doi.org/10.1051/0004-6361/202040181.
Анотація:
Context. Gas hydrates can be stabilised outside their window of thermodynamic stability by the formation of an ice layer – a phenomenon termed self-preservation. This can lead to a positive buoyancy for clathrate particles containing CO2 that would otherwise sink in the oceans of Enceladus, Pluto, and similar oceanic worlds. Aims. Here we investigate the implications of Lifshitz forces and low occupancy surface regions on type I clathrate structures for their self-preservation through ice layer formation, presenting a plausible model based on multi-layer interactions through dispersion forces. Methods. We used optical data and theoretical models for the dielectric response for water, ice, and gas hydrates with a different occupancy. Taking this together with the thermodynamic Lifshitz free energy, we modelled the energy minima essential for the formation of ice layers at the interface between gas hydrate and liquid water. Results. We predict the growth of an ice layer between 0.01 and 0.2 μm thick on CO, CH4, and CO2 hydrate surfaces, depending on the presence of surface regions depleted in gas molecules. Effective hydrate particle density is estimated, delimiting a range of particle size and compositions that would be buoyant in different oceans. Over geological time, the deposition of floating hydrate particles could result in the accumulation of kilometre-thick gas hydrate layers above liquid water reservoirs and below the water ice crusts of their respective ocean worlds. On Enceladus, the destabilisation of near-surface hydrate deposits could lead to increased gas pressures that both drive plumes and entrain stabilised hydrate particles. Furthermore, on ocean worlds, such as Enceladus and particularly Pluto, the accumulation of thick CO2 or mixed gas hydrate deposits could insulate its ocean against freezing. In preventing freezing of liquid water reservoirs in ocean worlds, the presence of CO2-containing hydrate layers could enhance the habitability of ocean worlds in our Solar System and on the exoplanets and exomoons beyond.
6
Boley, Kiersten M., Wendy R. Panero, Cayman T. Unterborn, Joseph G. Schulze, Romy Rodríguez Martínez, and Ji Wang. "Fizzy Super-Earths: Impacts of Magma Composition on the Bulk Density and Structure of Lava Worlds." Astrophysical Journal 954, no. 2 (September 1, 2023): 202. http://dx.doi.org/10.3847/1538-4357/acea85.
Анотація:
Abstract Lava worlds are a potential emerging population of Super-Earths that are on close-in orbits around their host stars, with likely partially molten mantles. To date, few studies have addressed the impact of magma on the observed properties of a planet. At ambient conditions, magma is less dense than solid rock; however, it is also more compressible with increasing pressure. Therefore, it is unclear how large-scale magma oceans affect planet observables, such as bulk density. We update ExoPlex, a thermodynamically self-consistent planet interior software, to include anhydrous, hydrous (2.2 wt% H2O), and carbonated magmas (5.2 wt% CO2). We find that Earth-like planets with magma oceans larger than ∼1.5 R ⊕ and ∼3.2 M ⊕ are modestly denser than an equivalent-mass solid planet. From our model, three classes of mantle structures emerge for magma ocean planets: (1) a mantle magma ocean, (2) a surface magma ocean, and (3) one consisting of a surface magma ocean, a solid rock layer, and a basal magma ocean. The class of planets in which a basal magma ocean is present may sequester dissolved volatiles on billion-year timescales, in which a 4 M ⊕ mass planet can trap more than 130 times the mass of water than in Earth’s present-day oceans and 1000 times the carbon in the Earth’s surface and crust.
7
Quick, Lynnae C., Aki Roberge, Guadalupe Tovar Mendoza, Elisa V. Quintana, and Allison A. Youngblood. "Prospects for Cryovolcanic Activity on Cold Ocean Planets." Astrophysical Journal 956, no. 1 (October 1, 2023): 29. http://dx.doi.org/10.3847/1538-4357/ace9b6.
Анотація:
Abstract We have estimated total internal heating rates and depths to possible subsurface oceans for 17 planets that may be cold ocean planets, low-mass exoplanets with equilibrium surface temperatures and/or densities that are consistent with icy surfaces and a substantial H2O content. We have also investigated the potential for tidally driven cryovolcanism and exosphere formation on these worlds. Estimated internal heating rates from tidal and radiogenic sources are large enough that all planets in our study may harbor subsurface oceans, and their geological activity rates are likely to exceed the geological activity rates on Jupiter’s moon Europa. Several planets are likely to experience enhanced volcanic activity rates that exceed that of Io. Owing to their relatively thin ice shells and high rates of internal heating, Proxima Cen b and LHS 1140 b are the most favorable candidates for telescopic detection of explosive, tidally driven cryovolcanism. Estimates for thin ice shells on Proxima Cen b, LHS 1140 b, Trappist-1f, and several Kepler planets suggest that any H2O vented into space during explosive cryovolcanic eruptions on these worlds could be sourced directly from their subsurface oceans. Like the icy moons in our outer solar system, cold ocean planets may be astrobiologically significant worlds that harbor habitable environments beneath their icy surfaces. These possibilities should be considered during analyses of observational data for small exoplanets from current and upcoming telescopes and during planning for a future space telescope mission aimed at characterization of potentially habitable exoplanets (e.g., Habitable Worlds Observatory).
8
Demissie, Fassil. "Living across worlds and oceans – an introduction." African and Black Diaspora: An International Journal 9, no. 2 (March 9, 2016): 125–33. http://dx.doi.org/10.1080/17528631.2016.1153812.
9
Napoleoni, Maryse, Lucía Hortal Sánchez, Nozair Khawaja, Bernd Abel, Christopher R. Glein, Jon K. Hillier, and Frank Postberg. "Probing the Oxidation State of Ocean Worlds with SUDA: Fe (ii) and Fe (iii) in Ice Grains." Planetary Science Journal 5, no. 4 (April 1, 2024): 95. http://dx.doi.org/10.3847/psj/ad2462.
Анотація:
Abstract Characterizing the geochemistry of Europa and Enceladus is a key step for astrobiology investigations looking for evidence of life in their subsurface oceans. Transition metals with several oxidation states, such as iron, may be tracers of the oxidation state of icy ocean moon interiors. Their detection, as well as the characterization of their oxidation states, on the moons’ (plume) ice grains would bring valuable new information about the geochemistry of both the subsurface oceans and surface processes. Impact ionization mass spectrometers such as the SUDA instrument on board Europa Clipper can analyze ice grains ejected from icy moons’ surfaces and detect ocean-derived salts therein. Here we record mass spectra analogs for SUDA using the Laser Induced Liquid Beam Ion Desorption technique for Fe2+ and Fe3+ salts (both sulfates and chlorides). We show that impact ionization mass spectrometers have the capability to detect and differentiate ferrous (Fe2+) from ferric (Fe3+) ions in both cation and anion modes owing to their tendency to form distinct ionic complexes with characteristic spectral features. Peaks bearing Fe3+, such as [Fe3+ (OH)2]+ and [Fe3+ (OH) a Cl b ]−, are particularly important to discriminate between the two oxidation states of iron in the sample. The recorded analog spectra may allow the characterization of the oxidation state of the oceans of Europa and Enceladus with implications for hydrothermal processes and potential metabolic pathways for life forms in their subsurface oceans.
10
JS, Craven. "Lands Abutting Seas, Oceans, 85% of Worlds Coronavirus Deaths." Journal of Biomedical Research & Environmental Sciences 3, no. 4 (April 2022): 397–405. http://dx.doi.org/10.37871/jbres1455.
Анотація:
The Worldometer Coronavirus registered six million deaths on March 03, 2022. 85% of the deaths occurred in lands directly abutting the World Seas and Oceans. The WHO, CDC and other World Public Health Organizations suggest that humidity can aid in the fight against COVID-19 [1]. The boundary of this comment is that it is directed at indoor air quality with perspective that 40-60% humidity is positive against COVID-19. The fact that almost all the World COVID-19 deaths are in lands directly abutting the Major World Seas and Oceans, with their inherent natural humidity, does not seem to be addressed in technical literature. There seems to be a conflict. This paper provides a breakdown of the World’s deadliest coronavirus regions at the six million death milestone, compares it to the earlier evaluation by the author captured in a WordPress website [2-10], and provides an in depth breakdown of the pandemic deaths and death rates in the lands abutting the Major World Seas and Oceans. Maps are provided showing the surrounding Countries or States of Countries with death and death rate tables for each of the World’s Major bodies of water. These are startling in similarity.
11
Lawrence, Justin D., Andrew D. Mullen, Frances E. Bryson, Chase J. Chivers, Ashley M. Hanna, Taylor Plattner, Elizabeth M. Spiers, et al. "Subsurface Science and Search for Life in Ocean Worlds." Planetary Science Journal 4, no. 2 (February 1, 2023): 22. http://dx.doi.org/10.3847/psj/aca6ed.
Анотація:
Abstract Several worlds in our solar system are thought to hold oceans of liquid water beneath their frozen surfaces. These subsurface ice and ocean environments are promising targets in the search for life beyond Earth, but they also present significant new technical challenges to planetary exploration. With a focus on Jupiter’s moon Europa, here we (1) identify major benefits and challenges to subsurface ocean world science, (2) provide a multidisciplinary survey of relevant sample handling and life detection technologies, and (3) integrate those perspectives into the Subsurface Science and Search for Life in Ocean Worlds (SSSLOW) concept payload. We discuss scientific goals across three complementary categories: (1) search for life, (2) assess habitability, and (3) investigate geological processes. Major mission challenges considered include submerged operation in high-pressure environments, the need to sample fluids with a range of possible chemical conditions, and detection of biosignatures at low concentrations. The SSSLOW addresses these issues by tightly integrated instrumentation and sample handling systems to enable sequential, complementary measurements while prioritizing preservation of sample context. In this work, we leverage techniques and technologies across several fields to demonstrate a path toward future subsurface exploration and life detection in ice and ocean worlds.
12
Polónia, Amélia, Ana Sofia Ribeiro, and Daniel Lange. "Connected oceans: New pathways in maritime history." International Journal of Maritime History 29, no. 1 (February 2017): 90–95. http://dx.doi.org/10.1177/0843871416679108.
Анотація:
The Atlantic, Indian, and Pacific Oceans and the Mediterranean Sea are no longer studied as distinct oceanic regions but interrogated as variegated worlds, interconnected in multiple ways. This Forum explores the various ways in which maritime history has been dealing with this trend. It shows how the notion of oceans as interactive spaces requires maritime historians to look beyond the shoreline by placing the interconnectedness of sea and land at the centre of their analysis. Focusing on littorals and port cities, the five papers in this Forum investigate the sea as zone of cultural encounter and vehicle of social and economic exchanges, and thereby illustrate how oceans connected people and ideas across the globe.
13
NUNCIO ZUNIGA, A., and W. FINK. "SUITABILITY OF SILICONE FOR SOFT-ROBOTIC EXPLORATION OF TERRESTRIAL AND EXTRATERRESTRIAL OCEAN WORLDS." Kosmìčna nauka ì tehnologìâ 29, no. 3 (June 9, 2023): 47–56. http://dx.doi.org/10.15407/knit2023.03.047.
Анотація:
This work revisits relevant mechanical and chemical properties of silicone rubber — Ecoflex in this study — to assess its suitability and viability for use in soft-robotic explorer construction and subsequent deployment and as a sealant for communication beacons, sensor pods, and other electronics in extreme planetary liquid environments, such as the depths of Earth’s oceans and extraterrestrial ocean worlds. Strain at a range of temperatures, as an indicator for operational durability, was tested under various endpoint clamp forces for several compound ratios. The temperature range at which silicone rubber remains pliable was assessed to determine its deployability. The re-binding property of cured silicone rubber samples with newly curing samples was investigated for its potential for additive manufacturing in soft robotics. Finally, the dissolution resistance, non-polarity, and electrical non-conductivity of silicone rubber were studied to assess its suitability for sealing electronics to be submerged in the salt water of both ocean and saturated salinity, as well as in hydrocarbon liquids. This work highlights critical aspects of silicone rubber for use in the construction, coating, and deployment of future soft robotic extraterrestrial liquid body explorers: The chosen silicone rubber Ecoflex is an electrically non-conducting sealant and pliable soft robotics material for temperatures above 50 °C, deployable in earthly extreme aqueous environments. Moreover, this work lays the foundation, albeit likely with different (silicone) rubbers/polymers due to much lower temperatures, for the robotic exploration of extraterrestrial liquid environments on ocean worlds, such as the hydrocarbon lakes on Titan and the putative subsurface oceans on Europa, Titan, and Enceladus.
14
Martin, Andrew, and Andrew McMinn. "Sea ice, extremophiles and life on extra-terrestrial ocean worlds." International Journal of Astrobiology 17, no. 1 (February 10, 2017): 1–16. http://dx.doi.org/10.1017/s1473550416000483.
Анотація:
AbstractThe primary aim of this review is to highlight that sea-ice microbes would be capable of occupying ice-associated biological niches on Europa and Enceladus. These moons are compelling targets for astrobiological exploration because of the inferred presence of subsurface oceans that have persisted over geological timescales. Although potentially hostile to life in general, Europa and Enceladus may still harbour biologically permissive domains associated with the ice, ocean and seafloor environments. However, validating sources of free energy is challenging, as is qualifying possible metabolic processes or ecosystem dynamics. Here, the capacity for biological adaptation exhibited by microorganisms that inhabit sea ice is reviewed. These ecosystems are among the most relevant Earth-based analogues for considering life on ocean worlds because microorganisms must adapt to multiple physicochemical extremes. In future, these organisms will likely play a significant role in defining the constraints on habitability beyond Earth and developing a mechanistic framework that contrasts the limits of Earth's biosphere with extra-terrestrial environments of interest.
15
Ludlow, Helen. "‘Bridging Two Oceans: Slavery in Indian and Atlantic Worlds’." South African Historical Journal 62, no. 3 (September 2010): 603–5. http://dx.doi.org/10.1080/02582473.2010.519905.
16
Peters, Kimberley, and Rachael Squire. "Oceanic Travels." Transfers 9, no. 2 (June 1, 2019): 101–11. http://dx.doi.org/10.3167/trans.2019.090207.
Анотація:
The seas and oceans, ships and boats, alongside other maritime activities and practices, have become a focus of work within the “new mobilities paradigm.” However, water worlds much like the space they occupy in the relation to the land remain situated in the margins of such work, despite an oceanic (re)turn in disciplines such as human geography, sociology, anthropology, and politics. Drawing from this recognition, this article seeks to make two contributions. First, following earlier, agenda-setting work, it makes a renewed call for mobilities scholarship to centralize work on oceans, ships, and other forms seagoing travel and life. Second, in doing so, it suggests such work needs to voyage more deeply and widely in the future, exploring mobilities beyond surficial connections and flows across our oceans, and making more expansive the subjects and objects and scales of investigation, under the remit of the “new mobilities paradigm.”
17
Biersteker, John B., Benjamin P. Weiss, Corey J. Cochrane, Camilla D. K. Harris, Xianzhe Jia, Krishan K. Khurana, Jiang Liu, Neil Murphy, and Carol A. Raymond. "Revealing the Interior Structure of Icy Moons with a Bayesian Approach to Magnetic Induction Measurements." Planetary Science Journal 4, no. 4 (April 1, 2023): 62. http://dx.doi.org/10.3847/psj/acc331.
Анотація:
Abstract Some icy moons and small bodies in the solar system are believed to host subsurface liquid water oceans. The interaction of these saline, electrically conductive oceans with time-varying external magnetic fields generates induced magnetic fields. Magnetometry observations of these induced fields in turn enable the detection and characterization of these oceans. We present a framework for characterizing the interiors of icy moons using multifrequency induction and Bayesian inference applied to magnetometry measurements anticipated from the upcoming Europa Clipper mission. Using simulated data from the Europa Clipper Magnetometer, our approach can accurately retrieve a wide range of plausible internal structures for Europa. In particular, the ocean conductivity is recovered to within ±50% for all internal structure scenarios considered, and the ocean thickness can be retrieved to within ±25 km for five out of seven scenarios. Characterization of the ice shell thickness to ±50% is possible for six of seven scenarios. Our recovery of the ice shell thickness is highly contingent on accurate modeling of magnetic fields arising from the interaction of Europa with the ambient magnetospheric plasma, while the ocean thickness is more modestly affected and the ocean conductivity retrieval is largely unchanged. Furthermore, we find that the addition of a priori constraints (e.g., static gravity measurements) can yield improved ocean characterization compared to magnetometry alone, suggesting that multi-instrument techniques can play a key role in revealing the interiors of Europa and other ocean worlds.
18
Akiba, Ryunosuke, Anton I. Ermakov, and Burkhard Militzer. "Probing the Icy Shell Structure of Ocean Worlds with Gravity–Topography Admittance." Planetary Science Journal 3, no. 3 (March 1, 2022): 53. http://dx.doi.org/10.3847/psj/ac4d2b.
Анотація:
Abstract The structure of the icy shells of ocean worlds is important for understanding the stability of their underlying oceans as it controls the rate at which heat can be transported outward and radiated to space. Future spacecraft exploration of the ocean worlds (e.g., by NASA’s Europa Clipper mission) will allow for higher-resolution measurements of gravity and shape than currently available. In this paper, we study the sensitivity of gravity–topography admittance to the structure of icy shells in preparation for future data analysis. An analytical viscous relaxation model is used to predict admittance spectra given different shell structures determined by the temperature-dependent viscosity of a tidally heated, conductive shell. We apply these methods to the ocean worlds of Europa and Enceladus. We find that admittance is sensitive to the mechanisms of topography support at different wavelengths and estimate the required gravity performance to resolve transitions between these mechanisms. We find that measuring admittance would be complementary to ice-penetrating radar in constraining shell thickness as it would cover the cases for which a direct ice–ocean interface detection is less favorable with radar, i.e., for warmer and thicker shells. Finally, we find that admittance may be used to constrain the tidal dissipation within the icy shell, which would be complementary to a more demanding measurement of the tidal phase lag.
19
Innes, Hamish, Shang-Min Tsai, and Raymond T. Pierrehumbert. "The Runaway Greenhouse Effect on Hycean Worlds." Astrophysical Journal 953, no. 2 (August 1, 2023): 168. http://dx.doi.org/10.3847/1538-4357/ace346.
Анотація:
Abstract Hycean worlds are a proposed subset of sub-Neptune exoplanets with substantial water inventories, liquid surface oceans, and extended hydrogen-dominated atmospheres favorable for habitability. We aim to quantitatively define the inner edge of the Hycean habitable zone (HZ) using a 1D radiative-convective model. As a limiting case, we model a dry hydrogen–helium envelope above a surface ocean. For a 1 bar (10,100 bar) atmosphere, the hydrogen greenhouse effect alone sets the inner edge of the HZ at 0.216 au (0.58, 3.71 au) for a Sun-like G star and at 0.0364 au (0.110, 0.774 au) for an 3500 K M star. Introducing water vapor into the atmosphere, the runaway greenhouse instellation limit is greatly reduced due to the presence of superadiabatic layers where convection is inhibited. This moves the inner edge of the HZ from ≈1 au for a G star to 1.6 au (3.85 au) for a Hycean world with a H2–He inventory of 1 bar (10 bar). For an M star, the inner edge is equivalently moved from 0.17–0.28 au (0.54 au). Our results suggest that most of the current Hycean world observational targets are not likely to sustain a liquid water ocean. We present an analytical framework for interpreting our results, finding that the maximum possible outgoing longwave radiation scales approximately inversely with the dry mass inventory of the atmosphere. We discuss the possible limitations of our 1D modeling and recommend the use of 3D convection-resolving models to explore the robustness of superadiabatic layers.
20
Fitzpatrick, Scott M., and Atholl Anderson. "Island Worlds Apart: Interaction and Remoteness on Seas and Oceans." Journal of Island and Coastal Archaeology 3, no. 1 (May 5, 2008): 1–3. http://dx.doi.org/10.1080/15564890801983610.
21
Nixon, Matthew C., and Nikku Madhusudhan. "How deep is the ocean? Exploring the phase structure of water-rich sub-Neptunes." Monthly Notices of the Royal Astronomical Society 505, no. 3 (June 17, 2021): 3414–32. http://dx.doi.org/10.1093/mnras/stab1500.
Анотація:
ABSTRACT Understanding the internal structures of planets with a large H2O component is important for the characterization of sub-Neptune planets. The finding that the mini-Neptune K2-18b could host a liquid water ocean beneath a mostly hydrogen envelope motivates a detailed examination of the phase structures of water-rich planets. To this end, we present new internal structure models for super-Earths and mini-Neptunes that enable detailed characterization of a planet’s water component. We use our models to explore the possible phase structures of water worlds and find that a diverse range of interiors are possible, from oceans sandwiched between two layers of ice to supercritical interiors beneath steam atmospheres. We determine how the bulk properties and surface conditions of a water world affect its ocean depth, finding that oceans can be up to hundreds of times deeper than on Earth. For example, a planet with a 300 K surface can possess H2O oceans with depths from 30–500 km, depending on its mass and composition. We also constrain the region of mass–radius space in which planets with H/He envelopes could host liquid H2O, noting that the liquid phase can persist at temperatures up to 647 K at high pressures of 218–$7\times 10^4$ bar. Such H/He envelopes could contribute significantly to the planet radius while retaining liquid water at the surface, depending on the planet mass and temperature profile. Our findings highlight the exciting possibility that habitable conditions may be present on planets much larger than Earth.
22
Steel, Frances. "Anglo-worlds in transit: connections and frictions across the Pacific." Journal of Global History 11, no. 2 (June 3, 2016): 251–70. http://dx.doi.org/10.1017/s1740022816000085.
Анотація:
AbstractThe emerging cultures of late nineteenth-century steamship mobility can be distinguished broadly by ocean basin and by specific route. In the Pacific, a steamship connection between Sydney and San Francisco was envisaged to forge and sustain strong bonds between regional ‘branches’ of the Anglo-Saxon race. This article moves beyond the rhetorical purchase of assumed affinities, to explore the more layered ways in which difference was articulated in transpacific encounters, and the attendant uncertainties and frictions in these evolving relations. When compared to routes bridging the Indian and Atlantic Oceans, with familiar imperial hierarchies and formalities behind them, British and colonial travellers in the Pacific were frequently unsettled by the more democratic and republican attitudes of the American crews and passengers they encountered. At the same time, Britain’s long-standing supremacy on the high seas provided a benchmark against which American enterprise and power in the Pacific could be assessed and found wanting.
23
Testón-Martínez, Sergio, Laura M. Barge, Jan Eichler, C. Ignacio Sainz-Díaz, and Julyan H. E. Cartwright. "Experimental modelling of the growth of tubular ice brinicles from brine flows under sea ice." Cryosphere 18, no. 5 (May 3, 2024): 2195–205. http://dx.doi.org/10.5194/tc-18-2195-2024.
Анотація:
Abstract. We present laboratory experiments on the growth of a tubular ice structure surrounding a plume of cold brine that descends under gravity into water with a higher freezing point. Brinicles are geological analogues of these structures found under sea ice in the polar regions on Earth. Brinicles are hypothesized to exist in the oceans of other celestial bodies, and being environments rich in minerals, serve a potentially analogous role as an ecosystem on icy-ocean worlds to that of submarine hydrothermal vents on Earth.
24
Shorttle, Oliver, Sean Jordan, Harrison Nicholls, Tim Lichtenberg, and Dan J. Bower. "Distinguishing Oceans of Water from Magma on Mini-Neptune K2-18b." Astrophysical Journal Letters 962, no. 1 (February 1, 2024): L8. http://dx.doi.org/10.3847/2041-8213/ad206e.
Анотація:
Abstract Mildly irradiated mini-Neptunes have densities potentially consistent with them hosting substantial liquid-water oceans (“Hycean” planets). The presence of CO2 and simultaneous absence of ammonia (NH3) in their atmospheres has been proposed as a fingerprint of such worlds. JWST observations of K2-18b, the archetypal Hycean, have found the presence of CO2 and the depletion of NH3 to <100 ppm; hence, it has been inferred that this planet may host liquid-water oceans. In contrast, climate modeling suggests that many of these mini-Neptunes, including K2-18b, may likely be too hot to host liquid water. We propose a solution to this discrepancy between observation and climate modeling by investigating the effect of a magma ocean on the atmospheric chemistry of mini-Neptunes. We demonstrate that atmospheric NH3 depletion is a natural consequence of the high solubility of nitrogen species in magma at reducing conditions; precisely the conditions prevailing where a thick hydrogen envelope is in communication with a molten planetary surface. The magma ocean model reproduces the present JWST spectrum of K2-18b to ≲3σ, suggesting this is as credible an explanation for current observations as the planet hosting a liquid-water ocean. Spectral areas that could be used to rule out the magma ocean model include the >4 μm region, where CO2 and CO features dominate: magma ocean models suggest a systematically lower CO2/CO ratio than estimated from free-chemistry retrieval, indicating that deeper observations of this spectral region may be able to distinguish between oceans of liquid water and magma on mini-Neptunes.
25
DiNicola, Michael, Samuel M. Howell, Kelli McCoy, Hayden Burgoyne, Zaki Hasnain, Kirk Reinholtz, and Sam Fleischer. "Resurfacing: An Approach to Planetary Protection for Geologically Active Ocean Worlds." Planetary Science Journal 3, no. 5 (May 1, 2022): 108. http://dx.doi.org/10.3847/psj/ac642d.
Анотація:
Abstract The putative and potential ocean worlds of our solar system span the asteroid belt to the Kuiper Belt, containing within their icy shells past or present global saltwater oceans. Among these worlds, those bearing signs of present-day geologic activity are key targets in the search for past or extant life in the solar system. As the icy surfaces of these bodies are modified by geologic processes, landforms are erased and replaced through what is called “resurfacing.” To avoid contaminating sites for robotic spacecraft exploration, planetary protection requirements obligate missions to these ocean worlds to demonstrate a less than 10−4 probability of introducing a viable terrestrial microorganism into a liquid water body. To constrain the probability of subsurface contamination, we investigate the interaction with geologic resurfacing on an active ocean world. Through the example of Europa, we show how the surface age can be used to constrain the resurfacing rate, a critical parameter to estimate the probability that nonsterile spacecraft material present on the surface is geologically incorporated into the subsurface, and extend this example to mission scenarios at Ganymede and Enceladus. This approach was critical to demonstrating compliance with planetary protection requirements for the Europa Clipper mission, reducing its probability of contamination by two to five orders of magnitude. We also show how a Europa lander mission might be brought close to complying with planetary protection requirements, that a Ganymede impactor could easily comply, and that the situation of Enceladus, while more complex, can greatly benefit from this approach.
26
Ambers, Andrew, and Rachel yacaaʔał George. "Fluid Internationalisms: The Ocean as a Source and Forum of Indigenous International Law." Borders in Globalization Review 5, no. 1 (March 5, 2024): 21–25. http://dx.doi.org/10.18357/bigr51202421801.
Анотація:
To rethink ‘the international’ necessarily enables revisioning where sources of law can be located, how normative paradigms operate in situ, and which processes foster cultural, political, and legal principles. In grounding this international reorientation in the ocean and ocean thinking, this analysis offers a brief point of entry into the worlds of Indigenous internationalisms from a coastal, oceanic reference of analysis. We underline not only how the ocean is an international law forum for Indigenous internationalisms, but also how they are vibrant spaces that foster connections between kin and generate legal principles through the methodology of reading seascapes. Through this process, what follows is a submerging of particular ideologies of ‘the international’ and an emerging account of ‘the international’ that facilitates a dynamic transcendence of thinking and being beyond state-premised borders, international relations, law, and sovereignty. Understanding oceans as Indigenous international law fora, as sources of Indigenous legalities, as physical interpretive legal methodologies, and as the connective structures that foster deep connections within and beyond an Indigenous nation, brings us into a socio-legal geography that suspends restrictive, colonial visions of ‘the international’ for a vibrant oceanic future. Recognizing and affirming these oceanic connections contributes to reinscribing Indigenous sovereignty at the scales of individuals, nations, and international relations.
27
KROUPA, SEBESTIAN, STEPHANIE J. MAWSON, and DORIT BRIXIUS. "Science and islands in Indo-Pacific worlds." British Journal for the History of Science 51, no. 4 (December 2018): 541–58. http://dx.doi.org/10.1017/s0007087418000730.
Анотація:
AbstractThis Introduction offers a conceptualization of the Indo-Pacific, its islands and their place within the history of science. We argue that Indo-Pacific islands present a remarkable combination of social, political and spatial circumstances, which speak to themes that are central to the history of science. Having driven movements of people and represented staging grounds for explorations, expansions and cross-cultural exchanges, these spaces have been at the forefront of historical change. The historiographies of the two oceans have traditionally emphasized indigenous agency while downplaying European historical trajectories, and therefore they provide historians of science with materials and methodologies that promise nuanced portrayals of knowledge production in cross-cultural settings. Rather than unifying the oceans into a cohesive narrative, we seek to uncover the many horizons of Indo-Pacific worlds and pluralize the spaces within which knowledge travelled at specific times, but not at others. Offering a middle plane between the globe and the region, islands are particularly productive sites for such analyses, as they bring to attention both localized kinds of agency and the impacts of colonialism and globalization. This special issue investigates what happens to knowledge within island spaces and demonstrates that even as small strips of land, islands can significantly enhance our understanding of the practices of knowledge making within the broader contours of world history. In bringing to the fore the contributions of actors from across the wider social spectrum and, especially, the interacting roles of indigenous agents and their traditions, Indo-Pacific worlds thus offer exciting new directions for a field which has often been dominated by a focus on European institutions.
28
Lingam, Manasvi, Amedeo Balbi, and Swadesh M. Mahajan. "A Bayesian Analysis of Technological Intelligence in Land and Oceans." Astrophysical Journal 945, no. 1 (March 1, 2023): 23. http://dx.doi.org/10.3847/1538-4357/acb6fa.
Анотація:
Abstract Current research indicates that (sub)surface ocean worlds essentially devoid of subaerial landmasses (e.g., continents) are common in the Milky Way and that these worlds could host habitable conditions, thence raising the possibility that life and technological intelligence (TI) may arise in such aquatic settings. It is known, however, that TI on Earth (i.e., humans) arose on land. Motivated by these considerations, we present a Bayesian framework to assess the prospects for the emergence of TIs in land- and ocean-based habitats (LBHs and OBHs). If all factors are equally conducive for TIs to arise in LBHs and OBHs, we demonstrate that the evolution of TIs in LBHs (which includes humans) might have very low odds of roughly 1 in 103 to 1 in 104, thus outwardly contradicting the Copernican principle. Hence, we elucidate three avenues whereby the Copernican principle can be preserved: (i) the emergence rate of TIs is much lower in OBHs, (ii) the habitability interval for TIs is much shorter in OBHs, and (iii) only a small fraction of worlds with OBHs comprise appropriate conditions for effectuating TIs. We also briefly discuss methods for empirically falsifying our predictions and comment on the feasibility of supporting TIs in aerial environments.
29
Ellis, Robert P., Mauricio A. Urbina, and Rod W. Wilson. "Lessons from two high CO2 worlds - future oceans and intensive aquaculture." Global Change Biology 23, no. 6 (October 20, 2016): 2141–48. http://dx.doi.org/10.1111/gcb.13515.
30
Ruiz, Javier, and Alberto G. Fairén. "Seas under ice: Stability of liquid-water oceans within icy worlds." Earth, Moon, and Planets 97, no. 1-2 (October 15, 2005): 79–90. http://dx.doi.org/10.1007/s11038-005-9052-8.
31
Bonati, Irene, Tim Lichtenberg, Dan J. Bower, Miles L. Timpe, and Sascha P. Quanz. "Direct imaging of molten protoplanets in nearby young stellar associations." Astronomy & Astrophysics 621 (January 2019): A125. http://dx.doi.org/10.1051/0004-6361/201833158.
Анотація:
During their formation and early evolution, rocky planets undergo multiple global melting events due to accretionary collisions with other protoplanets. The detection and characterization of their post-collision afterglows (magma oceans) can yield important clues about the origin and evolution of the solar and extrasolar planet population. Here, we quantitatively assess the observational prospects to detect the radiative signature of forming planets covered by such collision-induced magma oceans in nearby young stellar associations with future direct imaging facilities. We have compared performance estimates for near- and mid-infrared instruments to be installed at ESO’s Extremely Large Telescope (ELT), and a potential space-based mission called Large Interferometer for Exoplanets (LIFE). We modelled the frequency and timing of energetic collisions using N-body models of planet formation for different stellar types, and determine the cooling of the resulting magma oceans with an insulating atmosphere. We find that the probability of detecting at least one magma ocean planet depends on the observing duration and the distribution of atmospheric properties among rocky protoplanets. However, the prospects for detection significantly increase for young and close stellar targets, which show the highest frequencies of giant impacts. For intensive reconnaissance with a K band (2.2 μm) ELT filter or a 5.6 μm LIFE filter, the β Pictoris, Columba, TW Hydrae, and Tucana-Horologium associations represent promising candidates for detecting a molten protoplanet. Our results motivate the exploration of magma ocean planets using the ELT and underline the importance of space-based direct imaging facilities to investigate and characterize planet formation and evolution in the solar vicinity. Direct imaging of magma oceans will advance our understanding of the early interior, surface and atmospheric properties of terrestrial worlds.
32
Smith, Pete, Richard Whittle, and Peter Griffith. "LawSync: Navigating the ‘Blue Oceans’ Within the ‘Emerging’ Legal Services Markets." Legal Information Management 12, no. 3 (September 2012): 203–9. http://dx.doi.org/10.1017/s1472669612000473.
Анотація:
AbstractChange, it is said, is the only constant. Whilst it cannot be avoided, the worlds of legal education and legal services have arguably enjoyed an extended period where the impact of change has been comparatively minimal. Today, these worlds face significant changes due to a combination of market and regulatory forces. True, such changes are likely to be accompanied by challenges but with these challenges come opportunities. There is no reason why Law Schools and Law students cannot help to shape these changes and benefit from them. Peter Smith, Richard Whittle and Peter Griffith discuss LawSync™, a project that seeks to enable such influence and attract such benefits at Sheffield Hallam University. See http://www.lawsync.com and http://twitter.com/lawsync for more details.
33
Byers, Margaret Flicker, Sheldon Landsberger, and Erich Schneider. "The use of silver nanoparticles for the recovery of uranium from seawater by means of biofouling mitigation." Sustainable Energy & Fuels 2, no. 10 (2018): 2303–13. http://dx.doi.org/10.1039/c8se00228b.
Анотація:
Research currently being carried out by a consortium of national laboratory and university partners is leading to the development of advanced adsorbent materials suitable for the industrial-scale recovery of the essentially limitless supply of uranium naturally contained within the worlds oceans.
34
Verney, Michael A. "Book Review: Oceans Connect: Reflections on Water Worlds across Time and Space." International Journal of Maritime History 25, no. 2 (December 2013): 265–66. http://dx.doi.org/10.1177/084387141302500220.
35
Courville, Samuel W., Julie C. Castillo-Rogez, Mohit Melwani Daswani, Elodie Gloesener, Mathieu Choukroun, and Joseph G. O’Rourke. "Timing and Abundance of Clathrate Formation Control Ocean Evolution in Outer Solar System Bodies: Challenges of Maintaining a Thick Ocean within Pluto." Planetary Science Journal 4, no. 9 (September 1, 2023): 179. http://dx.doi.org/10.3847/psj/acf377.
Анотація:
Abstract Clathrate hydrates may represent a sizable fraction of material within the icy shells of Kuiper Belt objects and icy moons. They influence the chemical and thermal evolution of subsurface oceans by locking volatiles into the ice shell and by providing more thermal insulation than pure water ice. We model the formation of these crystalline compounds in conditions relevant to outer solar system objects, using Pluto as an example. Although Pluto may have hosted a thick ocean in its early history, Pluto’s overall heat budget is probably insufficient to preserve liquid today if its outer shell is pure water ice. One previously proposed reconciliation is that Pluto’s ocean has a winter jacket: an insulating layer of methane clathrate hydrates. Unfortunately, assessments of the timing, quantity, and type of clathrate hydrates forming within planetary bodies are lacking. Our work quantifies the abundance of clathrate-forming gases present in Pluto’s ocean from accreted ices and volatiles released during thermal metamorphism throughout Pluto’s history. We find that if Pluto formed with the same relative abundances of ices found in comets, then a buoyant layer of mixed methane and carbon dioxide clathrate hydrates may form above Pluto’s ocean, though we find it insufficient to preserve a thick ocean today. In general, our study provides methodology for predicting clathrate formation in ocean worlds, which is necessary to predict the evolution of the ocean’s composition and whether a liquid layer remains at present.
36
Heaney, Kevin D. "Rapid soundcape generate using energy flux modeling." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A189—A190. http://dx.doi.org/10.1121/10.0011060.
Анотація:
The impact of anthropocentric sound on the living marine environment has been a growing area of concern. Human induced sound sources include shipping, siesmic exploration, pile driving, US Navy sonars, and miscellaneous (rare) explosions. The most ubiquitous and least regulated sound source is shipping, which dominates the ocean soundscape for frequencies below 500 Hz in much of the worlds oceans. Modeling of the ocean soundscape has been conducted using adiabatic modes, the parabolic equation and ray-tracing. In this paper, we present the modeling of the ocean soundscape (shipping and wind) with an energy flux algorithm. This analytic approach is very efficient and can handle mildly range-dependent environments. The flux model is used to generate regional sound models. With the inclusion of horizontal and vertical angle information at the model source position, this model can generate the noise directionality efficiently and can be then use for the performance of any particular array against directional noise in the ocean environment.
37
Lingam, Manasvi, and Abraham Loeb. "Subsurface exolife." International Journal of Astrobiology 18, no. 2 (April 4, 2018): 112–41. http://dx.doi.org/10.1017/s1473550418000083.
Анотація:
AbstractWe study the prospects for life on planets with subsurface oceans, and find that a wide range of planets can exist in diverse habitats with ice envelopes of moderate thickness. We quantify the energy sources available to these worlds, the rate of production of prebiotic compounds, and assess their potential for hosting biospheres. Life on these planets is likely to face challenges, which could be overcome through a combination of different mechanisms. We estimate the number of such worlds, and find that they may outnumber rocky planets in the habitable zone of stars by a few orders of magnitude.
38
KUDRYASHOVA, Elena V., Mikhail Yu OPENKOV, and Larisa A. ZHGILEVA. "On the Methodology of Subglacial Oceans." Arctic and North, no. 43 (June 24, 2021): 253. http://dx.doi.org/10.37482/issn2221-2698.2021.43.253.
Анотація:
Throughout all periods of development, the history of mankind has been closely intertwined with the sea. Craving for perception of the unknown has always been favored for humans. The interrelations between people and water element were actively considered by the representatives of natural, exact and engineering sciences. Humanitarian thought can also make a contribution to the study of the oceans. The authors propose substantiation for the formation of the methodology of subglacial oceans. The methodology refers to the theory of thought and action. Modern methodology is capable of constructing the ways of thinking that solve new issues and problems. Openness to criticism of methodological thinking is its strong and promising aspect. The study of the exploration techniques of the “second space”, starting with the first steps and up to the modern attempt to create an underwater prototype of the International Space Station, leads the authors to the conclusion about the possible equivalence of space and Arctic technologies. Exploration of the ice cosmic worlds of Pluto, Jupiter and Saturn may precede the study of the Arctic region. The Arctic has the potential to become a testing site for future space missions. The sterility of space technologies can, on the other hand, provide the development of the green economy in the Arctic.
39
Mandt, Kathleen, Adrienn Luspay-Kuti, Olivier Mousis, and Sarah E. Anderson. "Surface Volatile Composition as Evidence for Hydrothermal Processes Lasting Longer in Triton’s Interior than Pluto’s." Astrophysical Journal 959, no. 1 (December 1, 2023): 57. http://dx.doi.org/10.3847/1538-4357/ad09b5.
Анотація:
Abstract Ocean worlds, or icy bodies in the outer solar system that have or once had subsurface liquid water oceans, are among the most compelling topics of astrobiology. Typically, confirming the existence of a subsurface ocean requires close spacecraft observations. However, combining our understanding of the chemistry that takes place in a subsurface ocean with our knowledge of the building blocks that formed potential ocean worlds provides an opportunity to identify tracers of endogenic activity in the surface volatiles of Pluto and Triton. We show here that the current composition of the volatiles on the surfaces and in the atmospheres of Pluto and Triton are deficient in carbon, which can only be explained by the loss of CH4 through a combination of aqueous chemistry and atmospheric processes. Furthermore, we find that the relative nitrogen and water abundances are within the range observed in building block analogs, comets, and chondrites. A lower limit for N/Ar in Pluto’s atmosphere also suggests source building blocks that have a cometary or chondritic composition, all pointing to an origin for their nitrogen as NH3 or organics. Triton’s lower abundance of CH4 compared to Pluto, and the detection of CO2 at Triton but not at Pluto points to aqueous chemistry in a subsurface ocean that was more efficient at Triton than Pluto. These results have applications to other large Kuiper Belt objects as well as the assessment of formation locations and times for the four giant planets given future probe measurements of noble gas abundances and isotope ratios.
40
Mathew, K. S. "Book Review: Rila Mukherjee, Oceans Connect: Reflections on Water Worlds across Time and Space." Indian Historical Review 41, no. 2 (November 3, 2014): 347–49. http://dx.doi.org/10.1177/0376983614544598.
41
Fukushi, Keisuke, Eigo Imai, Yasuhito Sekine, Takuma Kitajima, Baasansuren Gankhurel, Davaadorj Davaasuren, and Noriko Hasebe. "In Situ Formation of Monohydrocalcite in Alkaline Saline Lakes of the Valley of Gobi Lakes: Prediction for Mg, Ca, and Total Dissolved Carbonate Concentrations in Enceladus’ Ocean and Alkaline-Carbonate Ocean Worlds." Minerals 10, no. 8 (July 27, 2020): 669. http://dx.doi.org/10.3390/min10080669.
Анотація:
The nature of mineral precipitations in terrestrial alkaline soda lakes provides insights into the water chemistry of subsurface oceans on icy bodies in the outer solar system. Saturation analyses of terrestrial alkaline lakes have shown that the solution chemistries of lake waters are generally controlled by the presence of monohydrocalcite (MHC) and amorphous Mg-carbonate (AMC). However, direct observations of the formation of these metastable carbonates in natural alkaline lakes have been limited. This study provides evidence of in situ MHC formation in alkaline lakes, based on the water chemistry and mineralogy of suspended matter in Olgoy, Boon Tsagaan, and Orog Lakes (Valley of Gobi Lakes, Mongolia). The solution chemistries were close to saturation with respect to MHC and AMC, consistent with other alkaline lakes worldwide. Suspended matter was separated by the ultracentrifugation of lake water following freeze-drying. Our results show that MHC is the common mineral phase in the suspended matter. These observations confirm that MHC is the direct authigenic product of evaporation in alkaline lakes. The carbonate fraction in suspended matter from Olgoy Lake has a Mg/Ca ratio of 0.4, suggesting the formation of AMC in association with MHC. Based on the dissolution equilibria of AMC and MHC, we predict the Mg2+, Ca2+, and total dissolved carbonate concentrations in Enceladus’ ocean to be ~1 mmol/kg, ~10 μmol/kg, and 0.06–0.2 mol/kg, respectively, in the presence of AMC and MHC. We propose that the measurements of Mg contents in plumes will be key to constraining the total dissolved carbonate concentrations and chemical affinities of subsurface oceans on Enceladus and other alkaline-carbonate ocean worlds.
42
Wronkiewicz, Mark, Jake Lee, Lukas Mandrake, Jack Lightholder, Gary Doran, Steffen Mauceri, Taewoo Kim, et al. "Onboard Science Instrument Autonomy for the Detection of Microscopy Biosignatures on the Ocean Worlds Life Surveyor." Planetary Science Journal 5, no. 1 (January 1, 2024): 19. http://dx.doi.org/10.3847/psj/ad0227.
Анотація:
Abstract The quest to find extraterrestrial life is a critical scientific endeavor with civilization-level implications. Icy moons in our solar system are promising targets for exploration because their liquid oceans make them potential habitats for microscopic life. However, the lack of a precise definition of life poses a fundamental challenge to formulating detection strategies. To increase the chances of unambiguous detection, a suite of complementary instruments must sample multiple independent biosignatures (e.g., composition, motility/behavior, and visible structure). Such an instrument suite could generate 10,000× more raw data than is possible to transmit from distant ocean worlds like Enceladus or Europa. To address this bandwidth limitation, Onboard Science Instrument Autonomy (OSIA) is an emerging discipline of flight systems capable of evaluating, summarizing, and prioritizing observational instrument data to maximize science return. We describe two OSIA implementations developed as part of the Ocean World Life Surveyor (OWLS) prototype instrument suite at the Jet Propulsion Laboratory. The first identifies life-like motion in digital holographic microscopy videos, and the second identifies cellular structure and composition via innate and dye-induced fluorescence. Flight-like requirements and computational constraints were used to lower barriers to infusion, similar to those available on the Mars helicopter, “Ingenuity.” We evaluated the OSIA's performance using simulated and laboratory data and conducted a live field test at the hypersaline Mono Lake planetary analog site. Our study demonstrates the potential of OSIA for enabling biosignature detection and provides insights and lessons learned for future mission concepts aimed at exploring the outer solar system.
43
Helmreich, Stefan, and Caroline A. Jones. "Science/Art/Culture Through an Oceanic Lens." Annual Review of Anthropology 47, no. 1 (October 21, 2018): 97–115. http://dx.doi.org/10.1146/annurev-anthro-102317-050147.
Анотація:
Since the year 2000, artists have increasingly employed tools, methods, and aesthetics associated with scientific practice to produce forms of art that assert themselves as kinds of experimental and empirical knowledge production parallel to and in critical dialogue with science. Anthropologists, intrigued by the work of art in the age of its technoscientific affiliation, have taken notice. This article discusses bio art, eco art, and surveillance art that have gathered, or might yet reward, anthropological attention, particularly as it might operate as an allied form of cultural critique. We focus on art that takes oceans as its concern, tuning to anthropological interests in translocal connection, climate change, and the politics of the extraterritorial. We end with a call for decolonizing art–science and for an anti-colonial aesthetics of oceanic worlds.
44
Weber, Jessica M., Theresa C. Marlin, Medha Prakash, Bronwyn L. Teece, Katherine Dzurilla, and Laura M. Barge. "A Review on Hypothesized Metabolic Pathways on Europa and Enceladus: Space-Flight Detection Considerations." Life 13, no. 8 (August 11, 2023): 1726. http://dx.doi.org/10.3390/life13081726.
Анотація:
Enceladus and Europa, icy moons of Saturn and Jupiter, respectively, are believed to be habitable with liquid water oceans and therefore are of interest for future life detection missions and mission concepts. With the limited data from missions to these moons, many studies have sought to better constrain these conditions. With these constraints, researchers have, based on modeling and experimental studies, hypothesized a number of possible metabolisms that could exist on Europa and Enceladus if these worlds host life. The most often hypothesized metabolisms are methanogenesis for Enceladus and methane oxidation/sulfate reduction on Europa. Here, we outline, review, and compare the best estimated conditions of each moon’s ocean. We then discuss the hypothetical metabolisms that have been suggested to be present on these moons, based on laboratory studies and Earth analogs. We also detail different detection methods that could be used to detect these hypothetical metabolic reactions and make recommendations for future research and considerations for future missions.
45
Gürs, K., and A. W. Janssen. "Sea-level related molluscan plankton events (Gastropoda, Euthecosomata) during the Rupelian (Early Oligocene) of the North Sea Basin." Netherlands Journal of Geosciences - Geologie en Mijnbouw 83, no. 3 (September 2004): 199–208. http://dx.doi.org/10.1017/s0016774600020278.
Анотація:
AbstractSpacio-temporal distribution patterns of North Sea Basin Early Oligocene (Rupelian) pteropoda (holoplanktonic gastropods: Mollusca, Gastropoda, Euthecosomata) are studied. These patterns indicate three short term invasions of a single pteropod species during the Rupelian. These invasions are indicated here as Clio blinkae Event, Praehyalocylis laxeannulata Event and Clio jacobae Event. The conspicuously short occurrences of the species, their abundances and some lithological features of the pteropod bearing strata lead to the conclusion that these plankton events are linked to sea level high-stands allowing currents from the worlds oceans to enter into the North Sea Basin.
46
Gürs, K., and A. W. Janssen. "Sea-level related molluscan plankton events (Gastropoda, Euthecosomata) during the Rupelian (Early Oligocene) of the North Sea Basin." Netherlands Journal of Geosciences - Geologie en Mijnbouw 83, no. 3 (2004): 199–208. http://dx.doi.org/10.1017/s0016774600023507.
Анотація:
AbstractSpacio-temporal distribution patterns of North Sea Basin Early Oligocene (Rupelian) pteropoda (holoplanktonic gastropods: Mollusca, Gastropoda, Euthecosomata) are studied. These patterns indicate three short term invasions of a single pteropod species during the Rupelian. These invasions are indicated here as Clio blinkae Event, Praehyalocylis laxeannulata Event and Clio jacobae Event. The conspicuously short occurrences of the species, their abundances and some lithological features of the pteropod bearing strata lead to the conclusion that these plankton events are linked to sea level high-stands allowing currents from the worlds oceans to enter into the North Sea Basin.
47
Postberg, Frank, Yasuhito Sekine, Fabian Klenner, Christopher R. Glein, Zenghui Zou, Bernd Abel, Kento Furuya, et al. "Detection of phosphates originating from Enceladus’s ocean." Nature 618, no. 7965 (June 14, 2023): 489–93. http://dx.doi.org/10.1038/s41586-023-05987-9.
Анотація:
AbstractSaturn’s moon Enceladus harbours a global1 ice-covered water ocean2,3. The Cassini spacecraft investigated the composition of the ocean by analysis of material ejected into space by the moon’s cryovolcanic plume4–9. The analysis of salt-rich ice grains by Cassini’s Cosmic Dust Analyzer10 enabled inference of major solutes in the ocean water (Na+, K+, Cl–, HCO3–, CO32–) and its alkaline pH3,11. Phosphorus, the least abundant of the bio-essential elements12–14, has not yet been detected in an ocean beyond Earth. Earlier geochemical modelling studies suggest that phosphate might be scarce in the ocean of Enceladus and other icy ocean worlds15,16. However, more recent modelling of mineral solubilities in Enceladus’s ocean indicates that phosphate could be relatively abundant17. Here we present Cassini’s Cosmic Dust Analyzer mass spectra of ice grains emitted by Enceladus that show the presence of sodium phosphates. Our observational results, together with laboratory analogue experiments, suggest that phosphorus is readily available in Enceladus’s ocean in the form of orthophosphates, with phosphorus concentrations at least 100-fold higher in the moon’s plume-forming ocean waters than in Earth’s oceans. Furthermore, geochemical experiments and modelling demonstrate that such high phosphate abundances could be achieved in Enceladus and possibly in other icy ocean worlds beyond the primordial CO2 snowline, either at the cold seafloor or in hydrothermal environments with moderate temperatures. In both cases the main driver is probably the higher solubility of calcium phosphate minerals compared with calcium carbonate in moderately alkaline solutions rich in carbonate or bicarbonate ions.
48
Meier, K. J. S., L. Beaufort, S. Heussner, and P. Ziveri. "The role of ocean acidification in <i>Emiliania huxleyi</i> coccolith thinning in the Mediterranean Sea." Biogeosciences Discussions 10, no. 12 (December 16, 2013): 19701–30. http://dx.doi.org/10.5194/bgd-10-19701-2013.
Анотація:
Abstract. Ocean acidification is a result of the uptake of anthropogenic CO2 from the atmosphere into the ocean and has been identified as a major environmental and economic threat. The release of several thousands of petagrams of carbon over a few hundred years will overwhelm the capacity of the surface ocean reservoirs to absorb carbon. The recorded and anticipated changes in seawater carbonate chemistry will presumably affect the global oceanic carbonate production. Coccolithophores as the primary calcifying phytoplankton group, and especially Emiliania huxleyi as the most abundant species have shown a reduction of calcification at increased CO2 concentrations for the majority of strains tested in culture experiments. A reduction of calcification is associated with a decrease in coccolith weight. However, the effect in monoclonal cultures is relatively small compared to the strong variability displayed in natural E. huxleyi communities, as these are a mix of genetically and sometimes morphologically distinct types. Average coccolith weight is likely influenced by the variability in seawater carbonate chemistry in different parts of the worlds' oceans and on glacial/interglacial time scales due to both physiological effects and morphotype selectivity. An effect of the ongoing ocean acidification on E. huxleyi calcification has so far not been documented in situ. Here, we analyze E. huxleyi coccolith weight from the NW Mediterranean Sea in a 12 yr sediment trap series, and surface sediment and sediment core samples using an automated recognition and analyzing software. Our findings clearly show (1) a continuous decrease in the average coccolith weight of E. huxleyi from 1993 to 2005, reaching levels below pre-industrial Holocene and industrial 20th century values recorded in the sedimentary record, and (2) seasonal variability in coccolith weight that is linked to the coccolithophore production. The observed long-term decrease in coccolith weight is most likely a result of the changes in the surface ocean carbonate system. Our results provide first indications of an in situ impact of ocean acidification on coccolithophore weight in a natural E. huxleyi population even in the highly alkaline Mediterranean Sea.
49
KABIR, ANANYA JAHANARA. "Rapsodia Ibero-Indiana: Transoceanic creolization and the mando of Goa." Modern Asian Studies 55, no. 5 (January 11, 2021): 1581–636. http://dx.doi.org/10.1017/s0026749x20000311.
Анотація:
AbstractThe mando is a secular song-and-dance genre of Goa whose archival attestations began in the 1860s. It is still danced today, in staged rather than social settings. Its lyrics are in Konkani, their musical accompaniment combine European and local instruments, and its dancing follows the principles of the nineteenth-century European group dances known as quadrilles, which proliferated in extra-European settings to yield various creolized forms. Using theories of creolization, archival and field research in Goa, and an understanding of quadrille dancing as a social and memorial act, this article presents the mando as a peninsular, Indic, creolized quadrille. It thus offers the first systematic examination of the mando as a nineteenth-century social dance created through processes of creolization that linked the cultural worlds of the Indian and Atlantic Oceans—a manifestation of what early twentieth-century Goan composer Carlos Eugénio Ferreira called a ‘rapsodia Ibero-Indiana’ (‘Ibero-Indian rhapsody’). I investigate the mando's kinetic, performative, musical, and linguistic aspects, its emergence from a creolization of mentalités that commenced with the advent of Christianity in Goa, its relationship to other dances in Goa and across the Indian and Atlantic Ocean worlds, as well as the memory of inter-imperial cultural encounters it performs. I thereby argue for a new understanding of Goa through the processes of transoceanic creolization and their reverberation in the postcolonial present. While demonstrating the heuristic benefit of theories of creolization to the study of peninsular Indic culture, I bring those theories to peninsular India to develop further their standard applications.
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Biddanda, Bopaiah, Anthony Weinke, Ian Stone, Scott Kendall, Phil Hartmeyer, Wayne Lusardi, Stephanie Gandulla, John Bright, and Steven Ruberg. "Extant Earthly Microbial Mats and Microbialites as Models for Exploration of Life in Extraterrestrial Mat Worlds." Life 11, no. 9 (August 27, 2021): 883. http://dx.doi.org/10.3390/life11090883.
Анотація:
As we expand the search for life beyond Earth, a water-dominated planet, we turn our eyes to other aquatic worlds. Microbial life found in Earth’s many extreme habitats are considered useful analogs to life forms we are likely to find in extraterrestrial bodies of water. Modern-day benthic microbial mats inhabiting the low-oxygen, high-sulfur submerged sinkholes of temperate Lake Huron (Michigan, USA) and microbialites inhabiting the shallow, high-carbonate waters of subtropical Laguna Bacalar (Yucatan Peninsula, Mexico) serve as potential working models for exploration of extraterrestrial life. In Lake Huron, delicate mats comprising motile filaments of purple-pigmented cyanobacteria capable of oxygenic and anoxygenic photosynthesis and pigment-free chemosynthetic sulfur-oxidizing bacteria lie atop soft, organic-rich sediments. In Laguna Bacalar, lithification by cyanobacteria forms massive carbonate reef structures along the shoreline. Herein, we document studies of these two distinct earthly microbial mat ecosystems and ponder how similar or modified methods of study (e.g., robotics) would be applicable to prospective mat worlds in other planets and their moons (e.g., subsurface Mars and under-ice oceans of Europa). Further studies of modern-day microbial mat and microbialite ecosystems can add to the knowledge of Earth’s biodiversity and guide the search for life in extraterrestrial hydrospheres.