A fracture history on Enceladus provides evidence for a global ocean

Patthoff, D. A.; Kattenhorn, S. A.

doi:10.1029/2011gl048387

Cited by 84 publications

(100 citation statements)

References 42 publications

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“…In particular, the amplitude of longitudinal librations will be increased beyond those predicted for a solid Enceladus (21), with possibly important consequences for plume eruptive behavior; the same will be true of the obliquity, although this is predicted to be very small (29). Non-synchronous rotation, which has been suggested on the basis of geological mapping (30), is possible, and true polar wander (31) is more likely.…”

Section: S35 Isostatic Compensationmentioning

confidence: 99%

“…Again assuming full compensation and a shell thickness of ~30 km, the ratio Z 40 /Z 30 should be 0.978 and so based on the measured Z 30 we obtain Z 40 =2.94 x10 -7 m -1 . Together with the known value of H 40 (=-177 m), the predicted value of G 40 is -5.22x10 -5 , or just less than half the magnitude of G 30 . Ratio of core to mantle (ice+water) density (A) as a function of MOI factor for three choices of the ratio of mean density to mantle density.…”

Section: S35 Isostatic Compensationmentioning

confidence: 99%

“…The (3,0) terms provide an independent check on the assumption of isotropic admittance. The ratio Z 20 /Z 30 should be approximately 0.991 assuming a fully isostatic ice shell of mean thickness 30 km (eq. S14) and the properties listed in Table S6.…”

Section: S35 Isostatic Compensationmentioning

confidence: 99%

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The Gravity Field and Interior Structure of Enceladus

Iess

Stevenson

Parisi

et al. 2014

Science

371

415

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The small and active Saturnian moon Enceladus is one of the primary targets of the Cassini mission. We determined the quadrupole gravity field of Enceladus and its hemispherical asymmetry using Doppler data from three spacecraft flybys. Our results indicate the presence of a negative mass anomaly in the south-polar region, largely compensated by a positive subsurface anomaly compatible with the presence of a regional subsurface sea at depths of 30 to 40 kilometers and extending up to south latitudes of about 50 degrees. The estimated values for the largest quadrupole harmonic coefficients (10(6)J(2) = 5435.2 +/- 34.9, 10(6)C(22) = 1549.8 +/- 15.6, 1 sigma) and their ratio (J(2)/C-22 = 3.51 +/- 0.05) indicate that the body deviates mildly from hydrostatic equilibrium. The moment of inertia is around 0.335MR(2), where M is the mass and R is the radius, suggesting a differentiated body with a low-density core

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Section: S35 Isostatic Compensationmentioning

confidence: 99%

Section: S35 Isostatic Compensationmentioning

confidence: 99%

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The Gravity Field and Interior Structure of Enceladus

Iess

Stevenson

Parisi

et al. 2014

Science

371

415

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“…The measurements by the CASSINI mission to the Saturn moon Enceladus discovered a global ocean below the icy crust [1]. Hence, it is a possible candidate for extraterrestrial life within our solar system.…”

Section: Enceladus Explorer -Enexmentioning

confidence: 99%

“…To study different scenarios depending on various constraints (e.g. fixed starting positions of APUs, air filled cracks, inhomogeneities in ice quality, size of APU network) simulation modules for all APU components and a physical model of the ice are 1 …”

Section: Apu Networkmentioning

confidence: 99%

EnEx-RANGE - Robust autonomous Acoustic Navigation in Glacial icE

et al. 2017

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Abstract. Within the Enceladus Explorer Initiative of the DLR Space Administration navigation technologies for a future space mission are in development. Those technologies are the basis for the search for extraterrestrial life on the Saturn moon Enceladus. An autonomous melting probe, the EnEx probe, aims to extract a liquid sample from a water reservoir below the icy crust. A first EnEx probe was developed and demonstrated in a terrestrial scenario at the Bloodfalls, Taylor Glacier, Antarctica in November 2014. To enable navigation in glacier ice two acoustic systems were integrated into the probe in addition to conventional navigation technologies. The first acoustic system determines the position of the probe during the run based on propagation times of acoustic signals from emitters at reference positions at the glacier surface to receivers in the probe. The second system provides information about the forefield of the probe. It is based on sonographic principles with phased array technology integrated in the probe's melting head. Information about obstacles or sampling regions in the probe's forefield can be acquired. The development of both systems is now continued in the project EnEx-RANGE. The emitters of the localization system are replaced by a network of intelligent acoustic enabled melting probes. These localize each other by means of acoustic signals and create the reference system for the EnEx probe. This presentation includes the discussion of the intelligent acoustic network, the acoustic navigation systems of the EnEx probe and results of terrestrial tests.

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Self‐consistent generation of single‐plume state for Enceladus using non‐Newtonian rheology

et al. 2014

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The thermal dichotomy of Enceladus suggests an asymmetrical structure in its global heat transfer. So far, most of the models proposed that obtained such a distribution have prescribed an a priori asymmetry, i.e., some anomaly in or below the south polar ice shell. We present here the first set of numerical models of convection that yield a stable single-plume state for Enceladus without prescribed mechanical asymmetry. Using the convection code StagYY in a 2-D spherical annulus geometry, we show that a non-Newtonian ice rheology is sufficient to create a localized, single hot plume surrounded by a conductive ice mantle. We obtain a self-sustained state in which a region of small angular extent has a sufficiently low viscosity to allow subcritical to weak convection to occur due to the stress-dependent part of the rheological law. We find that the single-plume state is very unlikely to remain stable if the rheology is Newtonian, confirming what has been found by previous studies. In a second set of numerical simulations, we also investigate the first-order effect of tidal heating on the stability of the single-plume state. Tidal heating reinforces the stability of the single-plume state if it is generated in the plume itself. Lastly, we show that the likelihood of a stable single-plume state does not depend on the thickness of the ice shell.

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A fracture history on Enceladus provides evidence for a global ocean

Cited by 84 publications

References 42 publications

The Gravity Field and Interior Structure of Enceladus

The Gravity Field and Interior Structure of Enceladus

EnEx-RANGE - Robust autonomous Acoustic Navigation in Glacial icE

Self‐consistent generation of single‐plume state for Enceladus using non‐Newtonian rheology

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