The purpose of the NASA Cassini spacecraft, which was recently in the news, was to observe and study Saturn and its rings. Option 1, which suggests that the spacecraft was meant to carry materials for building the International Space Station, is incorrect because the Cassini spacecraft was not designed for transporting construction materials. Option 3, which states that the spacecraft was meant to monitor the approach of asteroids towards planet Earth, is also incorrect as this was not the objective of the Cassini mission. Option 4, which suggests that the spacecraft was intended for conducting space journeys for space tourists, is also incorrect. The Cassini spacecraft was primarily focused on the exploration and scientific study of Saturn and its rings, providing valuable data and insights into the composition, atmosphere, and activities of the planet.