VOA慢速英语:火星上的甲烷之谜：它意味着生命吗？

mission – n. an important task, usually involving travel somewhere

geological – adj. relating to the study of rocks, soil and the physical structure of the Earth

volume – n. the number of amount of something

microbial – adj. relating to microbes (very small living things)

motivate – v. to cause someone to behave in a particular way

determine – v. to control or influence directly

locate – v. find or discover the exact position of something