Modelling the orbital-tidal evolution of the Galilean moon Io

Modelling the orbital-tidal evolution of the Galilean moon Io

Kleinschneider, A.M.

Vermeersen, L.L.A. (mentor)

Aerospace Engineering

Space Engineering

MSc Spaceflight

2016-07-22

Io, the innermost Galilean moon of Jupiter, is the most volcanically active body in the Solar System. Its volcanism is driven by tidal foces, which are in turn sustained by the Laplace resonance between Io, Europa, and Ganymede. Tides have significant impact on a body's characteristics. The liquid ocean underneath Europa's icy surface is sustained by tidal heating. Similarly, tidally-heated exomoons may be able to support life well outside the habitable zone. Tidal forces influence the orbital evolution of a body. Consequently, the orbital evolution also affects the tidal evolution. Thus, it is important to understand how tides drive the Jupiter system and how sustainable the tidal heating that Io experiences is. Additionally, the interior structure of both Jupiter and Io are not very well understood nor constrained, but govern the orbital-tidal evolution via the Love number k2 and the quality factor Q. The orbital motion and tidal evolution of the Jupiter system was modelled. For this, existing TUDAT functions, for example for third-body gravitational acceleration, were combined with new tidal acceleration models. To enable long-term stability and fast computation of the integration a 4 th -order symplectic integrator with Wisdom-Holman split was applied. This type of energy-conserving integrator has limited applicability in the case of small dissipative forces, but requires fewer force evaluation than, for example, a Runge-Kutta integrator of the same order. A variety of reasonable values for k2 and Q have been tested, as well as extreme cases. It was found that the tides raised on Jupiter by Io have a negligible effect on the evolution of the system. On the other hand, the tides raised on Io by Jupiter profoundly impact the evolution of the inner moons. Over the course of five thousand years, Io migrates inwards by several thousand kilometre. In doing so, Europa is brought into a closer orbit as well, to retain the resonance. Similarly, the eccentricity of both Io and Europa decreases, which in turn reduces the dissipated tidal energy and -heating. With Io being in spin-orbit resonance, tidal forces due to tides on Io are not readily applied. Multiple variations of analytical expressions of tides on Io have been evaluated. The results of this thesis provide a qualtiative assessment of the evolution of the Jupiter system and of the sustainability of Io's strong volcanism. The insight gathered on the modelling of tides and their effects on spin-orbit-resonant bodies in particular will benefit future work on the evolution of moons in the Solar System as well as exosystems.

Io
Jupiter
tides
orbital evolution
orbital stability symplectic integrator
Love number
quality factor

http://resolver.tudelft.nl/uuid:573de551-1ee3-4fbb-bb40-6a1fb21d4b61

2017-07-22

Student theses

master thesis

(c) 2016 Kleinschneider, A.M.