NASA turned its attention to a series of robotic, relatively low-cost science and discovery missions. These included the Pioneer probes to Jupiter and Saturn; the twin Viking craft that landed on Mars; and Voyagers 1 and 2, which explored the outer planets and continue to this day flying beyond the Solar System into interstellar space. Both the Soviet Union and the United States also built space stations in the 1970s. Then, in 1981 the United States ramped up its human spaceflight program again with the first of what would be, at last count, scores of Space Shuttle missions. An expensive breakthrough design, the Shuttle rises into space like any other spacecraft, powered by both solid- and liquid-fuel rockets. But upon reentering the atmosphere, the craft becomes a glider, complete with wings, rudder, and landing gear—but no power. Shuttle pilots put their craft through a series of S turns to control its rate of descent and they get only one pass at landing. Among the many roles the Shuttle fleet has played, the most significant may be as a convenient though costly spacebased launchpad for new generations of satellites that have turned the world itself into a vast arena of instant communications.
As with all of the greatest engineering achievements, satellites and other spacecraft bring benefits now so commonplace that we take them utterly for granted. We prepare for an impending snowstorm or hurricane and tune in to our favorite news source for updates, but few of us think of the satellites that spied the storm brewing and relayed the warning to Earth. Directly and indirectly, spacecraft and the knowledge they have helped us gain not only contribute in myriad ways to our daily well-being but have also transformed the way we look at our own blue planet and the wider cosmos around us.