Launched in 1972 and weighing 258 kilograms (569 pounds), Pioneer 10 completed the first mission to the planet Jupiter and became the first of five artificial objects to achieve the escape velocity needed to leave the Solar System.

Scientists had long been intrigued by Mercury, the innermost planet of our solar system. Despite its proximity to the Sun, Mercury remained largely unexplored, with many questions remaining about its surface features, geological composition, and magn...