The 1960s conquest of the moon fueled a broad assault on the cosmos. Spacecraft launched into Earth orbit peered ever more sharply and deeply into the universe. So-called deep space missions were launched to actually go there, to the nearer planets. One day astronauts and cosmonauts will venture beyond the moon. Today, robotic spacecraft beam the sights and even sounds, tastes, and smells of faraway worlds back to our laboratories and living rooms.
Interplanetary space is vast and empty.
Even from the midst of the asteroid belt, one could hardly see with naked eyes more than a few faint asteroids among the myriad stars. The biggest Earthbound telescopes, sensing wavelengths spanning from the far-ultraviolet to radio, tell us much about the solar system, yet they pale when compared with getting up close. Rewards are greater if a spacecraft can land and return a rock or ice sample for detailed laboratory analysis. We can smell alien atmospheres with sophisticated gas analyzers, seismically hear planetquakes reverberating deep within a body, or probe the precise isotopic chemistry of materials collected from a body s surface. As a child learns life by playing, so explorers whether Lewis and Clark, Charles Darwin, or modern-day space scientists comprehend issues facing our species by addressing nature s mysteries.