VOA慢速英语:美国宇航局发现泰坦星有生命迹象?

mission – n. a task or job that someone is given to do

clue – n. something that helps a person find something, understand something, or solve a mystery or puzzle

beach – n. an area covered with sand or small rocks that is next to an ocean or lake

alien – n. from somewhere other than the planet Earth

familiar – adj. frequently seen, heard, or experienced

propeller – n. a device with two or more blades that turn quickly and cause a ship or aircraft to move

crust – n. a hard layer on the surface of something