19. Which spacecraft orbited Saturn since 2004, and mapped the surface of Titan? a. Cassini b. Huygens c. Magellan d. Rosetta

The correct answer is a. Cassini.<br /><br />The Cassini spacecraft orbited Saturn since 2004 and mapped the surface of Titan. The Cassini-Huygens mission was a collaborative project between NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI). The Cassini orbiter studied Saturn, its rings, and its moons, while the Huygens lander studied the surface of Titan.