Titan gravity and interior models
Sander Goossens
We have analyzed Cassini tracking data to determine Enceladus' gravity field and Titan's gravity field and tidal response as expressed by its degree 2 Love number k2. Our results are published in our paper "A low-density ocean inside Titan inferred from Cassini data". Details about the processing and implications of the results can be found in this paper. Here, we present the gravity solutions and the results of our Markov Chain Monte Carlo analysis of Titan's and Enceladus' interior structure.
Data
Gravity Fields
Spherical Harmonic Coefficients for the Gravity field of Enceladus.- download SHA here (unnormalized)
Spherical Harmonic Coefficients for the Gravity field of Titan.
- download SHA here (unnormalized)
Entries in these files are in the SHA format:
First line GM, radius, maximum degree, maximum order
Next lines: degree, order, C_lm, S_lm, formal error on C_lm, formal_error on S_lm (unnormalized)
The coefficients are unnormalized. For Titan, we include the constant contribution of the Love number on the degree 2 coefficients C2,0, C2,2, and S2,2. As such, the coefficients are thus “zero tide” coefficients (see here).
Markov-Chain Monte Carlo (MCMC) Results
Enceladus
Download the MCMC models here (22 MB, ZIP).Entries in this file are:
1. core radius [m],
2. ocean thickness [m],
3. Moment of Inertia factor,
4. bulk density fraction,
5. core density [kg/m3].
For Enceladus, we computed the core density from the bulk density and given radii (see Methods section of the paper). As a result, the bulk density fraction is always 1 and does not vary. This makes the Moment of Inertia faction the only parameter that varies.
Titan
Download the MCMC models here (407 MB, ZIP).Entries in this file are:
1. core radius[m],
2. ocean thickness [m],
3. core density [kg/m3],
4. ocean density [kg/m3],
5. high pressure ice viscosity [Pa s],
6. ice 1 viscosity [Pa s],
7. core rigidity [Pa],
8. Moment of Inertia fraction,
9. bulk density fraction,
10. k2,
11. h2,
12. l2,
13. Im(k2),
14. Im(h2),
15. Im(l2).
We also present a "corner plot" of Titan's MCMC output. This is also shown as Figure S12 in the Supplementary Information of our paper; here we present a high-resolution image (PNG, 16 MB).
Data Usage Policy
Please cite the following references when using any of the products described above:Publication: Goossens et al. (2024), A low-density ocean inside Titan inferred from Cassini data, Nature Astronomy, doi:10.1038/s41550-024-02253-4.
Dataset: Goossens, S. (2024). Titan gravity and interior models [Data set]. NASA Goddard Space Flight Center Planetary Geodesy Data Archive. doi:10.60903/GSFCPGDA-TITANK2.