A low-density ocean inside Titan inferred from Cassini data
Sander Goossens (NASA Goddard Space Flight Center)
B.G. van Noort (Southeastern Universities Research Association, Student TU Delft, Center for Research and Exploration in Space Science and Technology)
Alfonso Mateo (Student TU Delft)
E. Mazarico (NASA Goddard Space Flight Center)
Wouter van der Wal (TU Delft - Planetary Exploration)
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Abstract
The Cassini mission has provided measurements of the gravity of several moons of Saturn as well as an estimate of the tidal response, which is expressed as the degree 2 Love number k2 of its largest moon, Titan. The first estimates of Titan’s Love number were larger than pre-Cassini expectations. Interior modelling suggested it may be explained with a dense ocean, but the interpretation remains unclear. We analysed Cassini tracking data to determine Titan’s gravity field and its Love number. Our gravity results are consistent with earlier studies, but we find a lower Love number for Titan of k2 = 0.375 ± 0.06. This lower value follows from an elaborate investigation of the tidal effects. We show that a dense ocean is not implied by the obtained Love number; instead, a water or ammonia ocean is more probable. A lower density ocean can increase the likeliness of contact between the silicate core and ocean, which can leach minerals into the ocean and could promote its habitability.