The red color comes from the presence of the minerals iron oxide and olivine on its surface. Some astronomers once thought that Mars might have intelligent life. Science fiction writers were inspired to write stories about invaders from Mars, or Martians. In reality, Earth is “invading” Mars. A variety of unmanned spacecraft have been launched to visit Mars. Some spacecraft loop around the planet and study it from orbit, others have made treacherous landings, and some have crashed trying to land.