Hello everyone who have answered / commented on my question. Thanks for showing interest. What I was looking for is whether NASA or any other agency attempting to land something (any object) on moon, had anticipated that the object can "sink" into moon soil and knowingly took the risk and invested Time and money, Or they had crash landed objects on moon, and studied lunar soil in detail before deciding to go in for soft landing.
By the way, can anyone recommend any site (or many sites) which would give "absolutely in depth" knowledge about all lunar missions? (Knowledge pertaining to design aspects of equipments on board).