The Mass of Mars was first estimated from the orbits of the Martian moons, and 'confirmed' by the Ranger fly-bys. I will continue to argue that we have no factual basis for assuming the mass-orbit relationship of Mars and Mars' moons is precisely indentical to the Earth-moon relationship. The same is true of the Jovian and Saturn systems. There is mounting evidence that the moons of Saturn are composed of elements too heavy to meet the the Newtonian predictions of the masses of these moons. This is especially true of Phoebe (there is too much iron on the surface), Titan (sand where there should be water) and Enceladus (too much internal energy).Originally Posted by Hamlet
Some of it is not, I believe one of the Nature articles mentioned the penetrometer data compared favorably with sand. - they don't tend to put what they do not understand in published journals. These facts are the ones that tend to slip by unnoticed. Many of them are in the various Planetary Society articles and blog entries - I think the bit about finding benzene but not water vapor near the surface was in a 'Huygens one year later press release'. It is easy to see that the albedo and color of Titan is not anything like that of other water-ice coated moons like Enceladus. There has been considerable debate on the structure of the 'cat scratches', the dunes, and whether or not they resemble snow drifts on Unmannedspaceflight.comI've read all of the peer-reviewed Huygens papers and I don't recall a single one that supported these assertions.
MRO burned longer and used more fuel than expected to achieve the exact orbit desired. Venus Express burned exactly the expected amount of fuel for exactly the expected amount of time, but stayed in occultation 7 seconds longer than expected. 7 seconds means the orbit should be off by about 1%. In both cases, these are almost trivial differences, well within expected margins of errors, but as I have said many times, the orbital calculations should be very close, but not exactly correct - it is the masses of Mars and Venus used in making these calculations that are wrong.I've said my piece and have added the factual information on MRO.