HR: 1340h
AN: P53B-1236    [Abstracts]
TI: Detection of Solid Tides on Europa Through Ground-Tracking of a Low-Altitude, Altimeter- Equipped Orbiter
AU: * Casotto, S
EM: stefano.casotto@unipd.it
AF: University of Padua Dept. of Astronomy and Center for Space Studies (CISAS), Vic. Osservatorio, 3, Padova, 35122, Italy
AU: Padovan, S
EM: sebastiano.padovan@studenti.unipd.it
AF: University of Padua Center for Space Studies Dept. of Astronomy, Vic. Osservatorio, 3, Padova, 35122, Italy
AU: Bardella, M
EM: massimo.bardella@unipd.it
AF: University of Padua Dept. of Astronomy and Center for Space Studies (CISAS), Vic. Osservatorio, 3, Padova, 35122, Italy
AB: The possibility of detecting a global liquid ocean beneath the icy crust of Europa without the use of landers or ice penetrators rests on the measurement of the Love numbers h₂ and k₂. These are respectively related to the radial deformation of the surface and the consequent tidally-induced variation of the gravitational field of this icy satellite. Depending on the rigidity of the icy crust, the response of the Europan surface to the tidal forces gives an indication of the depth of a possible subsurface ocean. Previous studies in this area have addressed the detection of tidal surface deformations through the analysis of the tidally induced orbital perturbations of a Europan orbiter. As a preliminary study in preparation for future missions to Europa, as in the LAPLACE proposal to the European Space Agency, the approach followed here is to introduce the presence of an onboard altimeter. In this study we then generate synthetic measurements taken from an altimeter-equipped, low-altitude orbiter, supplemented with Earth-based tracking of the orbiter. For simplicity, ground-tracking is simulated as a range data-type. Altimeter measurements are simulated using parameters based on available models for the interior of Europa derived from Galileo mission data. Reference orbits were obtained by numerical investigations of the dynamically unstable near-Europa environment. Orbits were found to be stable over periods of approximately one to three months at altitudes of 100 km and inclinations varying from 75 degrees to 105 degrees. The measurements are consequently simulated over a period of one to two months. Under the hypothesis that Europan gravity field information of sufficient accuracy has been obtained in the first phase of the mission, the simulations address the detection of the solid tide related Love parameters h₂ and k₂. Results of this sensitivity study will be presented for a variety of orbital configurations with the aim to help in the design of future Europa exploration missions.
DE: 5770 Tidal forces
DE: 6024 Interiors (8147)
DE: 6221 Europa
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting