Orbital evolution of the Martian satellites
The tidal evolution of the Martian satellites has been investigated, and it is found that tides raised by the planet on the satellite can have significant consequences if the rigidity of the satellites is much less than the average rigidity of Mars. This would be the case if the satellites have a carbonaceous chondritic composition. Frequency dependent Q values of the planet or satellites can further enhance the evolution. Phobos, in particular, could have evolved from a parabolic orbit into a circular orbit within the age of the solar system, but the time required to shift Deimos remains inordinately long. If the present evolutions are representative of the past, the two orbits will have, at some time in the past, intersected, but the present orbit of Deimos does not favor a strong gravitational interaction with Phobos. Possibly, Deimos was part of a larger object, perhaps the core of a primordial body containing a large ice mantle. If it were sufficiently massive, such a body would have remained outside of Phobos. The backward extrapolated orbits of both satellites lead to a quite similar origin. The orbital inclinations have undergone little evolution, and this remains a severe constraint on the capture hypothesis, unless the captured bodies were initially in orbits inclined to the ecliptic. This cannot be excluded, a numerous asteroid families lie in orbits inclined by 20/sup 0/ or more to the ecliptic, in particular as these objects lie preferentially toward the outer limits of the asteroid belt, contain a higher percentage of carbonaceous chondritic material, and are more likely to be perturbed by Jupiter into Mars-crossing orbits.
- Research Organization:
- Research School of Earth Sciences, Australian National University, Canberra, A. C. T., Australia
- OSTI ID:
- 5842570
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 84:B10
- Country of Publication:
- United States
- Language:
- English
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