Land claims are predicated upon setting foot on the land in question. Landing some robots might not meet the requirements for recognition. The point is moot anyway while the 1967 UN Outer Space Treaty remains in effect, but if national claim is ever to be asserted, landing some human beings would be essential.
However, if the ship is launched from Costa Rica (a nation that did not sign the 1967 Outer Space Treaty), the point is moot.