Sunil,
The Moon has the presence of large areas of concentrations of very dense elements. These areas are so dense that they actually effect the trajectory of objects in orbit around the Moon (Newton's laws in action). Those areas we called "masscons" for large concentrations of mass. Unmanned mapping sats found most of these areas before we ever sent humans there.
The Apollo spacecraft was tracked by ground based stations and from those measurements, the trajectory was constucted. The "masscons" effect showed up exactly as predicted by the unmanned probes, and new ones were found as well. Yes, with tremendous effort, the tracking signals could be faked and the trajectory modeled rather than measured, but the task of faking that would have been an even more complex accomplishment than the landings.
