タイタンの固く耐候的な氷の殻である.
D Hemingway1, F Nimmo, H Zebker
1Department of Earth and Planetary Sciences, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA. djheming@ucsc.edu
Nature
|August 30, 2013
まとめ
タイタン (Titan) タイタン (Titan) タイタン (Titan)
科学分野:
- 惑星科学は惑星科学である.
- 地質物理学 地質物理学とは地質物理学です.
- 天体生物学 アストロバイオロジー
背景:
- 土星の最大の月であるタイタンは,地球上の地下海を持っていると考えられています.
- その外側の氷の殻の厚さは50~200キロメートルと推定されている.
- 以前のモデルでは,薄くて弱い氷の殻がコンベクションや静止補償によって動いている可能性を示唆していました.
研究 の 目的:
- タイタンの氷の殻の構造的性質を調査するために.
- 長い波長での重力と地形データを調和させるため.
- タイタンの外殻の剛性と地質学的活動を評価するために.
主な方法:
- 長波長における重力および地形データの分析,潮および回転効果を除く.
- 氷殻内の質量異常のモデリング.
- 重力場と表面の高さとの相関分析.
主要な成果:
- 長い波長での重力と地形間の有意な逆相関が発見されました.
- 氷の殻の底部の厚さによる負の重力異常は,表面特性の正の異常よりも優勢である.
- この発見は,弾性厚さ40kmを超える硬い氷殻と,かなりの表面浸食/堆積を必要とする.
結論:
- タイタンの氷殻は実質的に固体であり,地質学的に活動的ではなく,硬度が低い.
- 観測された重力-地形相関は,氷殻の底辺の地殻の厚みによって説明される.
- タイタンの慣性の瞬間は,以前に推定されたよりも高く,中心の凝縮量が少ないことを示している可能性があります.
さらに関連する動画
13:38Laser-Induced Fluorescence Emission L.I.F.E. as Novel Non-Invasive Tool for In-Situ Measurements of Biomarkers in Cryospheric Habitats
Published on: October 26, 2019
9.9K
07:48An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions
Published on: June 18, 2020
6.6K
関連する概念動画
States of Water
46.6K
Water exists in any one of the three classical states: solid (ice), liquid (water), and gas (steam or water vapor). The state of water depends on i) the intermolecular forces that draw molecules together and ii) the kinetic energy that leads to movements that pull them apart.
Water freezes when the intermolecular forces are greater than the kinetic energy. Unlike most other substances, water is less dense in its solid state than in its liquid state. This is because each water molecule can form...
Water freezes when the intermolecular forces are greater than the kinetic energy. Unlike most other substances, water is less dense in its solid state than in its liquid state. This is because each water molecule can form...
46.6K
Torque Free Motion
944
The torque-free motion refers to the movement of a rigid body in space when no external torques are acting upon it. This type of motion can be observed in environments where there are no external forces or frictions, like in outer space. For example, a rotation of Mars in space is a torque-free motion. Mars is an axisymmetric object, meaning it has an axis of symmetry along which it rotates, designated as the z-axis. The rotating frame of reference is defined such that the center of mass of...
944
Frost Action on Concrete
575
Concrete structures in cold climates, such as those along roadsides, can retain moisture. This moisture makes them susceptible to frost-related damage when temperatures fall below freezing. Adding moisture worsens the damage during temperature fluctuations, leading to repeated freezing and thawing. De-icing salts, spread over these structures to melt ice, add to the freeze-thaw cycle, and draw even more moisture into the concrete.
This freeze-thaw cycle primarily causes surface scaling, where...
This freeze-thaw cycle primarily causes surface scaling, where...
575
Frost Resistant Concrete
540
Concrete's susceptibility to frost damage during freeze-thaw cycles demands strategic measures to enhance its frost resistance. Employing techniques like air entrainment, adjusting the water-cement ratio, proper curing, and selecting appropriate aggregates are essential.
Introducing microscopic air bubbles into the concrete mix through air entrainment creates small voids that accommodate ice expansion, thereby reducing internal pressures and preventing cracking. The optimal amount of...
Introducing microscopic air bubbles into the concrete mix through air entrainment creates small voids that accommodate ice expansion, thereby reducing internal pressures and preventing cracking. The optimal amount of...
540
Outer Layers of the Cell Envelope
1.5K
The outermost layers of prokaryotic cells play a critical role in their survival, virulence, and interaction with the environment. These layers, often composed of polysaccharides, polypeptides, or proteins, form protective and adhesive structures that vary in organization and function.Capsules and Slime LayersCapsules are highly organized, tightly bound layers that firmly attach to the bacterial cell wall. Capsules are usually made of polysaccharides, though some are made of polypeptides. These...
1.5K
Archaeal Cell Wall
1.7K
Archaeal cell walls are structurally and compositionally distinct from their bacterial counterparts, lacking the characteristic peptidoglycan layer found in most bacteria. Instead, archaeal cell walls exhibit remarkable diversity, utilizing materials such as pseudomurein, polysaccharides, and proteins to construct their protective outer layers. This structural flexibility is closely tied to archaea's ecological adaptability.S-Layers: The Common Archaeal Cell WallThe S-layer is the most...
1.7K
