Two years ago, following the detection of a strongly magnetized ancient crust on Mars, David J. Stevenson, professor of planetary science at the California Institute of Technology (Caltech) published a theory that "Mars probably has a liquid, conductive outer core and might have a solid inner core like Earth," in a review article in the journal Nature in 2001. However, if Mars had a core like earths then it would possess atleast a small magnetic field which it does not. The lack of a modern day magnetic field on Mars has until recently been explained away by saying that the core of Mars is completly solid.

According to the data returned by the Mars Global Surveyor, Viking 1 & 2, and the Mars Pathfinder scientists discovered that the core of Mars was completly liquid. If the core is completely made of liquid then the only way to not produce a magnetic field is for the liquid not to be spinning. This none spinning hot liquid would be greatly succeptable to the pull of the suns gravity. If this is true then just as the sun and moon act to create high and low tides on earth the gravity of the sun pulling on a completely liquid core could cause high and low gravity tides by displacing mass to one side of the planet.

This is the reason I beleive so many missions fail, because we do not yet know how to perdict when the gravity will be high, low, or as expected.

Lets say we send a probe up for orbit and it comes in at a high gravity time then the altitude for orbit would need to be higher than orginally calculated and if its not the probe will never achieve orbit and crash to the planet.

have read several times that the orbits of the successful orbiters do have minor fluctuations. The probes that make it to Mars orbit I beleive make it at a normal gravity time when the mass of Mars is evenly distributed and gravity acts as it normally should for the most part.

Phobos cricles Mars every 7.7 hours or roughly 3 times a day. Deimos does so within 35 hours which is incredible rates. This alone is not much info but if you take the idea that both moons are captured asteroids then the speed of the moons seems a little strange.

If you take the example of spinning around with a hold on a rope and at the other end you have tied a brick. You start spinning and pull the brick in closer to you and your spinning and the bricks rotation will increase. Now push it out further than it was to begin with and you will slow back down a little. If you were to continue this cycle of pushing out the brick and pulling it in you would achieve a net speed gain. So is the same with the gravity pull of Mars pushing and pulling on Phobos and Deimos.

Also Phobos has a massively degrading oribit and is doomed to crash into Mars. Phobos is snugging up to the red planet at a rate of 6 feet every 50 or 100 years, I forget exactly which one. Phobos will either crash into Mars in 50 million years or be sheared by the gravity and become a ring.