Tectonic Processes on Europa: Tidal Stresses, Mechanical Response, and Visible Features

Greenberg, R.; Geissler, P. E.; Hoppa, G. V.; Tufts, B. R.; Durda, D. D.; Pappalardo, R.; Head, J. W.; Greeley, R.; Sullivan, Robert; Carr, M. H.

doi:10.1006/icar.1998.5986

Cited by 300 publications

(329 citation statements)

References 22 publications

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“…The R 2 coeffi cient for the so-obtained exponential regressions is above 0.99 in all the cases explored. Stresses giving f. = 2 X 10-IOs-I for T = 273 K are in general between,... .., 104 and ,... .., 105 Pa, in agreement with theoretical calculations of tidal stresses in the ice shell of Europa (e.g., Greenberg et al 1998;Harada and Kurita 2006). Figure 2 shows the value of Bo and Qejj as fllllctions of grain size.…”

Section: Composite Water Ice Viscositysupporting

confidence: 69%

Equilibrium Convection on a Tidally Heated and Stressed Icy Shell of Europa for a Composite Water Ice Rheology

Ruíz

2010

Earth Moon Planets

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Water ice I rheology is akey factorfor llllderstanding the thermal and mechanical state of the outer shell of the icy satellites. Ice flow involves several deformation mechanisms (both Newtonian and non-Newtonian), which contribute to different extents depending on the temperature, grain size, and applied stress. In this work I analyze tidally heated and stressed equilibrium convection in the ice shell of Europa by considering a composite viscosity law which includes diffusion creep, basal slip, grain bOlmdary sliding and dislo cation creep, and. The calculations take into aCcOllllt the effect of tidal stresses on ice flow and use grain sizes between 0.1 and 100 mm. An Arrhenius-type relation (useful for parameterized convective models) is fOlllld then by fi tting the calculated viscosity between 170 and 273 K to an exponential regression, which can be expressed in terms of pre exponential constant and effective activation energy.

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Section: Composite Water Ice Viscositysupporting

confidence: 69%

Equilibrium Convection on a Tidally Heated and Stressed Icy Shell of Europa for a Composite Water Ice Rheology

Ruíz

2010

Earth Moon Planets

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“…The surface is, however, covered by many tectonic features. The most striking features on Europa's surface are a series of dark lineaments and bands that crisscross the moon, which may have been produced by cracking due to tidal deformation (Greenberg et al, 1998) and icy volcanism (Figueredo and Greeley, 2004). Another major feature of Europa is the chaos terrain, which is a locally disrupted region demonstrating a jumbled and rough texture.…”

Section: Environment Of Europamentioning

confidence: 99%

Polymerization of Building Blocks of Life on Europa and Other Icy Moons

Kimura

Kitadai

2015

Astrobiology

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The outer Solar System may provide a potential habitat for extraterrestrial life. Remote sensing data from the Galileo spacecraft suggest that the jovian icy moons-Europa, Ganymede, and possibly Callisto-may harbor liquid water oceans underneath their icy crusts. Although compositional information required for the discussion of habitability is limited because of significantly restricted observation data, organic molecules are ubiquitous in the Universe. Recently, in situ spacecraft measurements and experiments suggest that amino acids can be formed abiotically on interstellar ices and comets. These amino acids could be continuously delivered by meteorite or comet impacts to icy moons. Here, we show that polymerization of organic monomers, in particular amino acids and nucleotides, could proceed spontaneously in the cold environment of icy moons, in particular the jovian icy moon Europa as a typical example, based on thermodynamic calculations, though kinetics of formation are not addressed. Observed surface temperature on Europa is 120 and 80 K in the equatorial region and polar region, respectively. At such low temperatures, Gibbs energies of polymerization become negative, and the estimated thermal structure of the icy crust should contain a shallow region (i.e., at a depth of only a few kilometers) favorable for polymerization. Investigation of the possibility of organic monomer polymerization on icy moons could provide good constraints on the origin and early evolution of extraterrestrial life.

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“…Europa's surface is pervasively fractured as a result of tidal deformation (Greenberg et al, 1998). A considerable amount of work has been done on both the fracture orientation (Kattenhorn, 2002;Greenberg et al, 2003;Spaun et al, 2003) and the direction and amount of motion (Hoppa et al, 2000;Prockter et al, 2002;Michalski and Greeley, 2002;Sarid et al 2002;Schulson, 2002;Patterson et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Normal faulting on Europa: implications for ice shell properties

Nimmo¹,

Schenk²

2006

Journal of Structural Geology

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We identify two likely normal faults on Europa, of lengths z30 and 11 km. A simple flexural model of fault-related topography gives effective elastic thicknesses of 1.2 and 0.15 km, respectively, and the resulting inferred fault strength is of order 1 MPa. The maximum fault displacement: length ratio for each fault is z0.02, comparable with values on silicate planets. We combine this observation with a modified linear elastic fracture mechanics model to conclude that the shear modulus of the Europan surface must be significantly less than that for unfractured ice. The low value of the modulus is probably due to near-surface fracturing or porosity, which will affect the material's radar properties and seismic velocities. For a likely reduction in shear modulus of an order of magnitude, the driving stresses inferred are about 6e8 MPa, much higher than present-day diurnal tidal stresses. However, stresses approaching these values can be generated by non-synchronous rotation or polar wander, while stresses exceeding these values arise during ice shell freezing. If the entire larger fault breaks, it will generate an event of seismic magnitude M s z5.3.

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Tectonic Processes on Europa: Tidal Stresses, Mechanical Response, and Visible Features

Cited by 300 publications

References 22 publications

Equilibrium Convection on a Tidally Heated and Stressed Icy Shell of Europa for a Composite Water Ice Rheology

Equilibrium Convection on a Tidally Heated and Stressed Icy Shell of Europa for a Composite Water Ice Rheology

Polymerization of Building Blocks of Life on Europa and Other Icy Moons

Normal faulting on Europa: implications for ice shell properties

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