Slichter modes of large icy satellites

Alexis Coyette, Tim Van Hoolst

Research output: Contribution to journalArticle

Abstract

Because of the presence of an ocean below the ice shell of icy satellites such as Europa, Callisto, Ganymede and Titan the solid interior of these satellites can be displaced with respect to the ice shell, similarly to the translational oscillation of the inner core of the Earth called the Slichter modes of the Earth. We construct a set of interior structure models of Europa, Callisto, Ganymede and Titan satisfying the observed mass, radius and moment of inertia and study the properties of the Slichter mode for these models. The periods obtained range from a few hours to a few tens of hours depending mainly on the ocean thickness. Ganymede has two Slichter modes since it is thought to have a liquid outer core besides a global subsurface ocean. The second Slichter mode describes essentially the oscillation of the solid inner core inside the liquid outer core and its period is determined principally by the thickness of the outer core. We study the possible observation of these modes with a lander on the surface or a spacecraft in orbit about Europa, Callisto, Ganymede or Titan. We show that an impactor with a radius of at least a few kilometers to a few tens of kilometers could excite the Slichter modes to a level observable by a lander. Such impacts occur on average once in >30 My for Europa, once in >70 My for Callisto, once in >40 My for Ganymede and once in >0.4 Gy for Titan. Observation of the Slichter mode would allow constraining the thickness of the ocean.
Original languageEnglish
Number of pages13
JournalIcarus
Volume231
DOIs
Publication statusPublished - 2014

Fingerprint

icy satellites
Ganymede
Callisto
Europa
Titan
outer core
oceans
inner core
ocean
oscillation
shell
ice
liquid
inertia
oscillations
impactors
radii
spacecraft
moments of inertia
liquids

Keywords

  • Satellites
  • dynamics
  • Callisto
  • Europa
  • Ganymede
  • Titan

Cite this

Coyette, Alexis ; Van Hoolst, Tim. / Slichter modes of large icy satellites. In: Icarus. 2014 ; Vol. 231.
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Slichter modes of large icy satellites. / Coyette, Alexis; Van Hoolst, Tim.

In: Icarus, Vol. 231, 2014.

Research output: Contribution to journalArticle

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T1 - Slichter modes of large icy satellites

AU - Coyette, Alexis

AU - Van Hoolst, Tim

PY - 2014

Y1 - 2014

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