Which space exploration vehicle has no crew and is used to collect data?

Look at the figure above. which atmospheric layer has around 80 percent of the mass of the earth's atmosphere? (hint: it's where the clouds seen on earth are formed.) a. exosphere b. troposphere c. stratosphere d. thermosphere

What environmental cues and landmarks do the geese use to determine the timing and direction of their migration over the mountains? how do they find their way?

Which of th following best describes how genes produce traits in an organism?