1.) Why did scientists start exploring Mars with flybys and orbiters instead of rovers?
They needed information before landing on the planet.
They weren’t interested in studying the rocks or radiation on Mars.
Dust storms kept them from using rovers.
They had to figure out how to make oxygen for the rovers.
2.) Why have scientists only sent unmanned spacecraft to Mars? What evidence leads you to that conclusion?
3.) What is one disadvantage of landers compared with other spacecraft?
They take about a year to get to Mars.
They have to wait for dust storms to pass.
They can only study the surface where they land.
They can never return to Earth.
4.) Which sentence from the passage best supports the conclusion that scientists should not yet send manned spacecraft to explore the surface of Mars?
"To learn about this planet, scientists have been sending unmanned spacecraft to Mars since the 1970s."
"A rover called Curiosity showed scientists that the radiation on Mars would be dangerous for humans."
"Mariner 9 had to wait a month for a dust storm to settle before it could take pictures of the surface."
"The Mars 2020 mission will test the air on Mars."
5.) Some scientists think that people might be able to live on Mars in the future. What evidence from the text supports their inference that this might be possible?