The desire to explore space has captured the imagination of humans for centuries. Before the invention of rockets and other advanced technologies in the 20th century, however, people could only travel very short distances above Earth’s surface with kites, balloons, and airplanes. The development of rockets and spacecraft made it possible for humans to live in orbiting space stations and to visit the Moon. Scientists have used the unique conditions of space to perform a wide variety of scientific experiments on living things—including humans, plants, and microscopic organisms.
It is widely recognized that space exploration brings significant physical and economic benefits to nations. This includes stimulation of electronics miniaturization and advances in medical, telecommunications, manufacturing, and navigation systems. It also fosters international cooperation among countries, which is vital to a healthy world society. These benefits are cited as reasons for national governments to support their space programs.
In addition, many scientists believe that venturing into space helps to unite people of all backgrounds and beliefs. This may be especially important as the challenges and opportunities of an interstellar future loom on the horizon.
The most common type of spacecraft is an artificial satellite, which orbits a larger astronomical body—such as the Sun or the Moon. A space probe is any craft, crewed or uncrewed, that goes beyond Earth’s gravitational pull and escapes its solar system to study other planets or the universe beyond them. Both Voyager 1 and 2 have reached the outer limits of our solar system and are currently coasting through interstellar space.