Through space exploration humans have learned a great deal about the planets, stars, and other objects in space. More than five thousand spacecraft have been launched into space to gather information since 1957. Without space travel, NASA may never have developed many of the things we take for granted today, such as cell phone cameras, CAT scans, and ski boots. This useful and interesting resource discusses the many types of manned and unmanned spacecraft, describes how a rocket works, and looks ahead to space travel's future.