The age of space exploration opened in the sixth decade of the 20th century. In its first two decades, robot probes and then human beings first ventured beyond the limits of the Earth's atmosphere and landed on another celestial object, the Moon. Probes have since gone on to explore the far realms of the solar system and beyond. Although the space age is still young, it is based on a long history of theoretical and …showed first 75 words of 373 total…

…showed last 75 words of 373 total…In addition, objects placed in orbit around the Earth provide platforms both for astronomical studies and for a wide range of scientific and practical activities relating to the Earth's surface, including surveys of resources, studies of weather processes, and the relaying of communications and television images between distant points. All of these subject areas lie within the field of space exploration, and this article also observes the social and military considerations that are necessarily involved.