| Title | Moments of inertia and rotational stability of Mars: lithospheric support of sub-hydrostatic rotational flattening |
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| Author | Bills, B G; James, T S |
| Source | Journal of Geophysical Research vol. 104, no. E4, 1999 p. 9081-9096, https://doi.org/10.1029/1998je900003 |
| Year | 1999 |
| Alt Series | Geological Survey of Canada, Contribution Series 1998112 |
| Publisher | Wiley-Blackwell |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Area | Mars |
| Subjects | extraterrestrial geology; mathematical and computational geology; lithosphere; bulk density determinations; structural interpretations; gravity field; load love numbers |
| Illustrations | plots |
| Released | 1999 04 01 |
| Abstract | A revised estimate of the spin axis precession rate of Mars has recently been obtained via analysis of range and range-rate data from the Viking and Pathfinder landers. When combined with existing
estimates of the degree 2 spherical harmonic coefficients of the gravitational field, this yields a complete determination of the inertia tensor of Mars. Despite this progress, there are still numerous unresolved issues related to the internal
structure and rotational dynamics of Mars. We compare results of two different approaches to this problem. In one approach, the observed gravitational field is conceptually partitioned into hydrostatic and nonhydrostatic contributions. In the other
approach, the input to the system is partitioned into rotational and load components, and the internal structure (density and elastic rigidity) determines the response. We demonstrate that there is an important, and still unresolved trade-off between
lithospheric thickness and the shape of the load component of the gravity field. As the lithospheric thickness is increased, the required load departs more from axial symmetry. The load corresponding to zero lithospheric thickness is nearly symmetric
about an equatorial axis, but if the lithospheric thickness is closer to 100 km, the required load is a fully triaxial ellipsoid, with the intermediate moment of inertia halfway between the least and greatest moments. The symmetry of the load has
considerable influence on the long-term rotational stability of Mars. |
| GEOSCAN ID | 209712 |
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