An object in this meaning is the same thing as an objective[?] or task[?]. It comes from old project terminology and refers to the act of actually performing something according to a plan, or rather "according to a project" (the word "project" used to mean "plan").
... travelled to China in the 13th century.
John Wesley Powell, (1834-1902), explorer, environmentalist
Nathaniel Pryor[?], (c 1785-1850), US explorer
Pytheas, (died ...