It is clear that imperatives other than profits or nationalism will have to compel human beings to leave their tracks on the planet's reddish surface.
很明显，除了利益和民族主义，其他紧急的事物将迫使人类在地球表面留下他们的足迹。
2
Although their missions blended commercial and political-military imperatives, the explorers involved all accomplished some significant science simply by going where no scientists had gone before.